EP4731165A1

EP4731165A1 - Composite material of bismuth oxycarbonate and polymers for filtering ultraviolet radiation

Info

Publication number: EP4731165A1
Application number: EP24736418.5A
Authority: EP
Inventors: Aude VIVES; Cynthia GHOBRIL
Original assignee: LOreal SA
Current assignee: LOreal SA
Priority date: 2023-06-22
Filing date: 2024-06-21
Publication date: 2026-04-29
Also published as: KR20260028077A; FR3150109A1; WO2024261325A1; CN121729210A

Abstract

Composite material of bismuth oxycarbonate and polymers for filtering ultraviolet radiation The present invention relates to a composite material comprising at least one particle of bismuth oxycarbonate of formula (I) (BiO)2-x(CO3), and solvates thereof, such as hydrates thereof, in which -04 < x < 0.6, the largest mean dimension of said particles being less than 400 nm; and at least one polymer, to the process for preparing them, and to cosmetic compositions and uses of said composite materials.

Description

Description Title: Composite material of bismuth oxycarbonate and polymers for filtering ultraviolet radiation Technical field The present invention relates to the field of sun protection and more particularly to composite materials of bismuth oxycarbonate and polymers, for use thereof in filtering ultraviolet radiation. The invention also relates to a composition, in particular a cosmetic composition, notably comprising composite materials of bismuth oxycarbonate particles and polymers. Keratin materials are exposed daily to sunlight. It is known that light radiation with wavelengths of between 280 nm and 400 nm makes it possible to tan the human epidermis. However, rays with wavelengths of between 280 and 320 nm, referred to as UV-B rays, are detrimental to the development of a natural tan. This exposure is also liable to induce impairment of the biomechanical properties of the epidermis, which is reflected by the appearance of wrinkles, leading to premature ageing of the skin. It is also known that UV-A rays with wavelengths of between 320 and 400 nm penetrate more deeply into the skin than UV-B rays. UV-A rays promote rapid and persistent pigmentation of the skin. Under normal conditions, daily exposure to UV-A radiation, even of short duration, can also cause damage to collagen and elastin fibers, which is reflected by a modification to the microrelief of the skin, the appearance of wrinkles and uneven pigmentation (i.e. liver spots, non-uniformity of the complexion, etc.). Furthermore, prolonged exposure to the sun can also dry out the hair, making it brittle. Consequently, it is of utmost importance to protect keratin materials, notably human keratin materials such as the skin. Prior art In order to counteract these undesirable effects, it is common practice to formulate organic and/or inorganic anti-UV-A and/or anti-UV-B screening agents in compositions intended to provide sun protection. Many photoprotective cosmetic compositions for the skin have been proposed to date. They generally contain organic UV-screening agents and/or inorganic UV-screening agents, which act according to their own chemical nature and according to their own physical properties by absorption, reflection or scattering of the UV radiation. They generally contain combinations of oil-soluble organic UV-screening agents and/or of water-soluble organic UV-screening agents combined with metal oxide pigments, such as titanium dioxide (TiO2) or zinc oxide (ZnO). As regards customary organic screening agents, they must have acceptable cosmetic properties, good solubility in the customary solvents, notably in oils, and good photostability, alone and in combination. They must also be colorless or have a color that is cosmetically acceptable to consumers. These organic screening agents are generally used as mixtures and such combinations of screening agents can limit the formulation range. In addition, nowadays, photoprotection using inorganic UV-screening agents is a highly important expectation of consumers, because they consider mineral sunscreens to be safer. TiO₂ and ZnO are the most commonly used mineral UV-screening agents. However, one of the major drawbacks of such mineral screening agents is that, once applied to the skin, they cause a whitening effect on the skin which is cosmetically undesirable and generally not particularly appreciated by users. This effect is all the more pronounced when the concentration of mineral screening agents in the composition is high, which limits the concentration thereof in sun formulations. To avoid this problem, it would of course be possible to use reduced amounts of inorganic screening agent(s), but the resulting compositions, which would certainly result in films having acceptable transparency on the skin, would then no longer offer suitable protection in the UV range, which greatly limits the utility of such an option. Furthermore, aside from significant whitening, using large amounts of these UV-screening agents leads to unpleasant sensations after application to the skin, and notably causes sensations of roughness and dryness on the skin, in the case of significant and regular use of the products. Consumers are increasingly seeking products which are effective but are also very easy to apply, are comfortable for longer and have satisfactory sensory properties. Disclosure of the invention There is thus still a need for inorganic UV-screening agents that afford efficient photoprotection and that do not have the drawbacks presented above. In particular, there is still a need for inorganic UV-screening agents that are capable of efficiently blocking UV rays, in particular in the UV-A and UV-B range, and notably UV-B rays, which have high transparency to visible light, which do not whiten the keratin materials to which they are applied, and which have good cosmetic properties. There is notably still a need for mineral UV-screening agents other than titanium dioxide or zinc oxide, which prove just as effective, which are transparent, which do not cause sensations of roughness and dryness on the skin, and which are easy to formulate, notably at high concentrations. The present invention is specifically directed towards proposing novel mineral UV- screening agents which can meet these expectations. Summary of the invention Thus, according to a first of its aspects, the present invention relates to a composite material comprising: a) at least one particle of bismuth oxycarbonate of formula (I) (BiO)_2-x(CO₃), and solvates thereof, such as hydrates thereof, in which -0.4 < x < 0.6, the largest mean dimension of said particles being less than 400 nm; and b) at least one polymer. Preferably, the present invention relates to a composite material comprising: a) at least one particle of bismuth oxycarbonate of formula (I) (BiO)2-x(CO3), and solvates thereof, such as hydrates thereof, in which -0.4 < x < 0.6, the largest mean dimension of said particles being less than 400 nm; and b) at least one polymer chosen from polyethylene glycols, polyethylene amines, polypropylene glycols, polyvinyl alcohols, polyacrylic acids and salts thereof, polymethacrylic acids and salts thereof, polymethyl methacrylates, polyvinyl sulfonates, polystyrene sulfonates, polylactic acids and salts thereof, polycaprolactones, polyglycolic acids, polyacetoacetates, poly(lactic-co-glycolic) acids, celluloses and derivatives thereof, alginic acids and salts thereof, carrageenans, starches, pectins, inulins, dextrans and derivatives thereof, xanthan gum, ulvans, lignosulfonates and salts thereof, chitins and chitosans, pullulans, polyvinyl alcohols and polyhydroxystearic acid, and/or copolymers thereof, or mixtures thereof. Preferably, the present invention relates to a composite material comprising: a) at least one particle of bismuth oxycarbonate of formula (I) (BiO)_2-x(CO₃), and solvates thereof, such as hydrates thereof, in which -0.4 < x < 0.6, the largest mean dimension of said particles being less than 400 nm; and b) at least one polymer chosen from natural hydrophilic and/or lipophilic and/or amphiphilic and anionic and/or cationic and/or neutral polysaccharides, preferably chosen from natural hydrophilic anionic and/or cationic and/or neutral polysaccharides, more preferentially, chosen from neutral or anionic polysaccharides, and more preferentially chosen from carrageenans, chitosan, dextran sulfates, (di)starch phosphate, pullulans and the forms thereof esterified (or acetylated) by a carboxylic acid, preferably comprising from 1 to 30 carbon atoms, more particularly from 8 to 20 carbon atoms, such as myristoyl pullulan and ulvan. In particular, the bismuth oxycarbonate particles are of formula (BiO)₂(CO₃), and solvates thereof, such as hydrates thereof. Combinations of bismuth oxide with polymers such as alginates, chitosan, polyvinyl alcohol are already proposed in various fields other than sun protection of keratin materials, for example radiopacity for embolization (US 8012454, EP 1 531874, US 7947 073), in medical equipment (US 6387978), or for combating gastric hyperacidity (US 3257275, US 6024987 A). However, these documents do not make any mention of the field of UV screening, nor do they describe composite materials comprising bismuth oxides according to the invention. Preferably, the mass ratio of bismuth oxycarbonate particle(s) a) to polymers b) ranges from 0.01 to 50, preferably from 0.2 to 15, more preferentially from 0.3 to 10, and more preferentially from 0.5 to 8.5. Preferably, the mean size of the largest dimension of the composite material particle according to the invention is less than or equal to 1 µm, and more preferentially less than or equal to 500 nm, even more preferentially less than or equal to 450 nm. In particular, the bismuth oxycarbonate particles are in the form of tubes, platelets and/or rods, preferably in the form of platelets and/or rods. Preferably, the polymer(s) b) are chosen from polyethylene glycols, polyethylene amines, polypropylene glycols, polyvinyl alcohols, polyacrylic acids and salts thereof, polymethacrylic acids and salts thereof, polymethyl methacrylates, polyvinyl sulfonates, polystyrene sulfonates, polylactic acids and salts thereof, polycaprolactones, polyglycolic acids, polyacetoacetates, poly(lactic-co-glycolic) acids, celluloses and derivatives thereof, alginic acids and salts thereof, carrageenans, starches, pectins, inulins, dextrans and derivatives thereof, xanthan gum, ulvans, lignosulfonates and salts thereof, chitins and chitosans, pullulans, polyvinyl alcohols and polyhydroxystearic acid, and/or copolymers thereof, or mixtures thereof. In particular, the polymer(s) b) are chosen from sodium lignosulfonates, calcium lignosulfonates, polyanethol sulfonate, sodium alginate, carboxymethylcelluloses, hydroxyethylcelluloses, dextran sulfate salts, carrageenans, chitosans, myristoyl pullulan, polyvinyl alcohols, and/or copolymers thereof, or mixtures thereof. More particularly, the molar ratio between the number of moles of coating compound(s) and the number of moles of core compound(s) ranges from 0.0001 to 20, preferably ranges from 0.005 to 15, more preferentially ranges from 0.01 to 10, and even more preferentially ranges from 0.05 to 5. Surprisingly, and as emerges from the examples below, the inventors discovered that the composite materials according to the invention have excellent efficacy for filtering ultraviolet radiation, and in particular UV-B rays, and high transparency in the visible range, and make it possible to afford the composition containing them cosmetic properties that are satisfactory to consumers. For the purposes of the present invention, the term "composite material" means a heterogeneous particulate solid material comprising at least two immiscible components, the components of which are linked via physical and/or chemical interactions. For the purposes of the present invention, the term “high transparency in the visible range” means particles having a high transmission of rays between 400 and 780 nm. For the purposes of the present invention, the term “efficacy for filtering ultraviolet radiation” means particles having a threshold absorbance in the UV range, in the dispersion medium comprising said particles at a mass fraction of 0.005%, of greater than 0.25, preferably greater than or equal to 0.30, and even more preferentially greater than or equal to 0.35. The higher the threshold absorbance, the greater the efficacy for filtering UV radiation. UV-B radiation means the wavelength range extending from 280 to 320 nm. UV-A radiation means the wavelength range extending from 320 to 400 nm. Visible light means the wavelength range extending from 400 to 780 nm. Thus, for the purposes of the present invention, the term “UV-screening agent” is intended to denote any compound which screens out ultraviolet (UV) radiation in the wavelength range extending from 280 nm to 400 nm. The term “UV-B screening agent” is intended to denote any compound which screens out ultraviolet (UV) radiation in the wavelength range extending from 280 nm to 320 nm. The term “UV-A screening agent” is intended to denote any compound which screens out ultraviolet (UV) radiation in the wavelength range extending from 320 nm to 400 nm. For the purposes of the present invention, the term “fatty substance” means an organic compound that is immiscible in water at ordinary temperature (25 °C) and at atmospheric pressure (760 mmHg) (solubility of less than 5%, preferably less than 1% and even more preferentially less than 0.1%); in addition, the fatty substances are miscible in particular in all proportions in organic solvents under the same temperature and pressure conditions, for instance in halogenated solvents such as chloroform or dichloromethane, lower alcohols such as ethanol, or aromatic solvents such as benzene or toluene. The term “organic or mineral acid salt” more particularly means salts chosen from a salt derived from i) hydrochloric acid HCl, ii) hydrobromic acid HBr, iii) sulfuric acid H₂SO₄, iv) alkylsulfonic acids: Alk-S(O)2OH such as methanesulfonic acid and ethanesulfonic acid; v) arylsulfonic acids: Ar-S(O)2OH such as benzenesulfonic acid and toluenesulfonic acid; vi) citric acid; vii) succinic acid; viii) tartaric acid; ix) lactic acid; x) alkoxysulfinic acids: Alk-O-S(O)OH such as methoxysulfinic acid and ethoxysulfinic acid; xi) aryloxysulfinic acids, such as tolueneoxysulfinic acid and phenoxysulfinic acid; xii) phosphoric acid H3PO4; xiii) acetic acid CH₃C(O)OH; xiv) triflic acid CF₃SO₃H; and xv) tetrafluoroboric acid HBF₄; and salts of “acidic” amino acids such as glutamic acid and aspartic acid salts. The term “organic or mineral base salts” means salts of bases or alkaline agents as defined below, such as alkali metal hydroxides, such as sodium hydroxide or potassium hydroxide, aqueous ammonia, amines or alkanolamines, or else salts of “basic” amino acids such as lysine or arginine. The term “cationic counterion” means a cation or a cationic group derived from an organic or mineral base salt counterbalancing the anionic charge of at least one ingredient of the composition according to the invention; more particularly the cationic counterion is chosen from i) alkali metals such as sodium, potassium, preferably Na⁺, ii) alkaline-earth metals such as calcium; iii) ammonium R₄N⁺ with R, which may be identical or different, representing a hydrogen atom, or a (C1-C6) alkyl group optionally substituted with one or more hydroxy groups; preferably, R represents a hydrogen atom or a (C₁-C₄) alkyl group such as methyl. This efficacy of the composite materials according to the invention is, to the inventors’ knowledge, characterized for the first time. It has never been proposed to use composite materials of bismuth oxycarbonate particles and polymers in cosmetic compositions intended for the effective filtering of UV radiation, in particular UV-B radiation. The composite materials according to the invention are notably intended for protecting keratin materials, in particular the skin and the hair, against UV radiation, in particular in cosmetic compositions for the fields of sun protection, care or treatment of the hair and makeup. Thus, according to another aspect, the present invention also relates to the non-therapeutic cosmetic use of a composite material according to the invention, for filtering UV radiation, preferably UV-B radiation, comprising at least the application to keratin materials of a composition comprising a composite material according to the invention. The present invention also relates to a non-therapeutic cosmetic process for filtering UV radiation, preferably UV-B radiation, comprising at least the application to keratin materials of a composition comprising the composite materials of bismuth oxycarbonate and polymers as defined above. The present invention also relates to processes for preparing the composite materials according to the invention. The term “keratin materials” notably means the skin, including the scalp, the lips, and keratin fibers such as the hair, the eyelashes, the eyebrows, in particular the skin and/or the hair, and preferably the skin. The term “at least one” is equivalent to “one or more”. The terms “between... and...”, “comprises from ... to...”, “formed from ... to...” and “ranging from... to...” should be understood as including the limits, unless otherwise specified. Other characteristics, variants and advantages of the compositions according to the invention will emerge more clearly on reading the description and the examples that follow. Brief description of the drawings [Fig 1] depicts the absorbance spectra obtained by UV-visible spectrophotometry on dispersions of composite materials A1, A2, B1 and B2 at 0.005% by mass in water. [Fig 2] depicts the absorbance spectra obtained by UV-visible spectrophotometry on dispersions of composite materials C1, C2, C3 and C4 at 0.005% by mass in water. [Fig 3] depicts the absorbance spectra obtained by UV-visible spectrophotometry on dispersions of composite materials D, E1, E2, F1 and F2 at 0.005% by mass in water. [Fig 4] depicts the absorbance spectra obtained by UV-visible spectrophotometry on dispersions of composite materials G, H1 and H2 at 0.005% by mass in water. [Fig 5] depicts the absorbance spectra obtained by UV-visible spectrophotometry on dispersions of composite materials I, J1 and J2 at 0.005% by mass in water. [Fig 6] depicts the absorbance spectra obtained by UV-visible spectrophotometry on dispersions of composite materials K, L1 and L2 at 0.005% by mass in water. [Fig 7] depicts the absorbance spectra obtained by UV-visible spectrophotometry on dispersions of composite materials M, N1, N2, O1 and O2 at 0.005% by mass in water. [Fig 8] depicts the absorbance spectra obtained by UV-visible spectrophotometry on dispersions of composite materials P1, P2, Q1 and Q2 at 0.005% by mass in water. [Fig 9] depicts the absorbance spectra obtained by UV-visible spectrophotometry on dispersions of composite materials S1, S2 and R at 0.005% by mass in a water/propylene glycol/Tween 20 mixture. [Fig 10] depicts the absorbance spectrum obtained by UV-visible spectrophotometry on dispersions of composite material T at 0.005% by mass in a water/propylene glycol/Tween 20 mixture. [Fig 11] depicts the absorbance spectra obtained by UV-visible spectrophotometry on dispersions of Alfa Aesar Bismutite, and of composite material U, at 0.005% by mass in water. [Fig 12] depicts the absorbance spectrum obtained by UV-visible spectrophotometry on dispersions of composite materials V and W at 0.005% by mass in water. [Fig 13] depicts the absorbance spectrum obtained by UV-visible spectrophotometry on dispersions of composite materials X, Y and Z at 0.005% by mass in water. [Fig 14] depicts the absorbance spectrum obtained by UV-visible spectrophotometry on dispersions of composite material AA at 0.005% by mass in a water/propylene glycol/Tween 20 mixture. [Fig 15] depicts the absorbance spectrum obtained by UV-visible spectrophotometry on dispersions of composite material DD at 0.005% by mass in water. [Fig 16] depicts the absorbance spectra obtained by UV-visible spectrophotometry on dispersions of composite materials I and EE at t = 0 h and t = 48 h, and sodium lignosulfonate, at 0.005% by mass in water. [Fig 17] depicts the absorbance spectra obtained by UV-visible spectrophotometry on dispersions of composite materials D and FF at t = 0 h and t = 48 h, with T = 45 °C for t = 48 h, at 0.005% by mass in water. [Fig 18] depicts the absorbance spectrum obtained by UV-visible spectrophotometry on dispersions of composite materials HH at 0.005% by mass in a water/propylene glycol/polysorbate 20 mixture with respective mass fractions of 49.85/49.85/0.30. [Fig 19] depicts the absorbance spectrum obtained by UV-visible spectrophotometry on dispersions of composite materials II at 0.005% by mass in a water/propylene glycol/polysorbate 20 mixture with respective mass fractions of 49.85/49.85/0.30. [Fig 20] depicts the absorbance spectrum obtained by UV-visible spectrophotometry on dispersions of composite materials JJ at 0.005% by mass in a water/propylene glycol/polysorbate 20 mixture with respective mass fractions of 49.85/49.85/0.30. [Fig 21] depicts the absorbance spectrum obtained by UV-visible spectrophotometry on composition A1.1 diluted in deionized water at 0.005% by weight of composite material A1. Detailed description The invention relates to a composite material comprising a) at least one particle of bismuth oxycarbonate of formula (I) (BiO)2-x(CO3), and solvates thereof, such as hydrates thereof, in which -0.4 < x < 0.6, the largest mean dimension of said particles being less than 400 nm; and b) at least one polymer. COMPOSITE MATERIAL As indicated above, the composite material comprises a) at least one bismuth oxycarbonate particle and b) at least one polymer. According to a particular embodiment, the mass ratio of bismuth oxycarbonate particle(s) a) to polymer(s) ranges from 0.01 to 50, preferably from 0.2 to 15, more preferentially from 0.3 to 10, and more preferentially from 0.5 to 8.5. The term “mean size” or “mean dimension” is intended to denote the number-average value of the dimensions of the composite material or of the particles. The dimensions of the composite materials or of the particles can be determined by transmission electron microscopy, for example using a Hitachi HT 7700 microscope, notably at an acceleration voltage of 100 kV, by scanning electron microscopy, or else by measuring the specific surface area via the BET method, or else using a laser particle size analyzer. Preferably, the dimensions of the particles are determined by transmission electron microscopy, for example using a Hitachi HT 7700 microscope, notably at an acceleration voltage of 100 kV, or by scanning electron microscopy. Preferentially, the measurement is performed on the smallest individualized or individualizable objects. The number-average value can be calculated by analyzing images obtained using software such as the ImageJ software (C.A. Schneider, W.S. Rasband, K.W. Eliceiri, NIH Image to ImageJ: 25 years of image analysis, Nat. Methods.9 (2012) 671–675). The mean dimension is chosen from the mean length L, the mean width l, the mean thickness e, or the mean diameter d. The term “mean size of the largest dimension” or “largest mean dimension” of the composite materials or the particles is intended to denote the largest mean dimension of a surface, such as a face, that can be measured between two diametrically opposed points on an individual particle. In the context of the present invention, this dimension is defined as the maximum Féret diameter. The “length” L of a composite material or of a particle is the largest dimension thereof which can be observed in an image taken in a direction perpendicular to the plane on which said composite material or said particle is resting. The “width” l and the “thickness” e of a composite material or of a particle are the lengths of the long and short axes, respectively, of the smallest possible ellipse in which the median cross section of said composite material or of said particle can be inscribed. The “diameter” d of a composite material or of a particle is the largest dimension that can be observed along a line which passes through the center of a circle or a sphere. The composite materials according to the invention may be of various shapes and structures. The composite materials according to the invention may notably be spherical, cubic, platelet- shaped, cylindrical or tubular. The shape of said composite materials will notably depend on the process for preparing them and on the operating conditions. In particular, the composite materials according to the invention may be in the form of tubes, platelets, sheets, rods, spheres, flowers, pompoms, threads, filaments, fibers, needles, cubes or any mixture thereof. The composite materials according to the invention may also aggregate in the form of superstructures. For example, platelets, tubes and/or rods can aggregate in the form of spheres, flowers or pompoms. According to one particular embodiment, the composite materials according to the invention are in the form of spheres. According to a particular embodiment, the composite materials according to the invention are in the form of tubes, platelets and/or rods. Even more preferentially, the composite materials according to the invention are in the form of platelets and/or rods. The composite materials in the form of platelets or rods or tubes thus differ notably from spherical or fibrous forms or flowers, pompoms, threads, filaments, needles or cubes. It is understood that the composite materials according to the invention can be used in the form of a mixture. In particular, the composite materials according to the invention can be used in a mixture in any proportion of platelets and/or of rods and/or of tubes. Likewise, a composite material in the form of spheres can be composed of a polymer matrix and bismutite platelets, i.e. two morphologies represented within the same composite. It is also possible to achieve the morphology of a film containing bismutite particles by lyophilization. According to a preferred embodiment, the composite materials used according to the invention are predominantly or exclusively in the form of platelets. A composite material in “platelet” form has a length greater than the width thereof, and a width greater than the thickness thereof. According to a preferred embodiment, the composite materials are predominantly or exclusively in the form of rods. A composite material in “rod” form has a solid cylindrical form and the length thereof L is greater than the diameter thereof d, or has a prism form, the base of which is solid and polygonal, preferably triangular or hexagonal, and the diameter d of the circle within which this polygonal base is circumscribed is less than the length L of the prism. According to a preferred embodiment, the composite materials are predominantly or exclusively in the form of tubes. A composite material in “tube” form has a hollow cylindrical form and the length thereof L is greater than the diameter thereof d. For the purposes of the present invention, the term “predominantly in the form of platelets/rods/tubes” is intended to denote that at least 50% by number, in particular at least 70% by number, or even at least 90% by number of the composite materials are in the form of platelets/rods/tubes, respectively. The bismuth oxycarbonate particle(s) a), and the polymer(s) b) may be arranged in different ways within the composite material. According to one embodiment, the composite material may have at least one core and at least one coating as a layer or layers surrounding said core. Thus, they may comprise at least one coating as a layer or layers surrounding a core that is chemically different from said coating. The coating may be formed of one or more layers. The core of the composite materials may consist of at least a) one or more particles of bismuth oxycarbonate of formula (I) (BiO)2-x(CO3), and solvates thereof, such as hydrates thereof, in which -0.4 < x < 0.6, the largest mean dimension of said particles being less than 400 nm. According to a particular embodiment, the core of the composite materials may consist of at least one polymer b). The composite material may contain bismuth oxycarbonate particles a) as defined above in the core and/or in the layer(s) forming the coating. According to a particular embodiment, the material contains at least one bismuth oxycarbonate particle a) as defined above in the core. According to another particular embodiment, the material contains bismuth oxycarbonate particles a) as defined above in the coating. According to one embodiment, the polymer(s) b) can cover all or part of at least one bismuth oxycarbonate particle a). According to another embodiment, the polymer(s) b) can be entirely or partially covered with at least one bismuth oxycarbonate particle a). In particular, the mass ratio of bismuth oxycarbonate particle(s) a) to polymers ranges from 0.01 to 50, preferably from 0.2 to 15, more preferentially from 0.3 to 10, and more preferentially from 0.5 to 8.5. According to a particular embodiment, the composite materials according to the invention contain at least one layer surrounding the core. Thus, according to a particular embodiment, the composite materials according to the invention comprise a core comprising at least a) at least one particle of bismuth oxycarbonate of formula (I) (BiO)2-x(CO3), and solvates thereof, such as hydrates thereof, in which -0.4 < x < 0.6, the largest mean dimension of said particles being less than 400 nm, said core being covered on the surface, continuously or discontinuously, with a coating comprising b) at least one polymer. According to a first variant of the invention, the composite materials in accordance with the invention include a coating, also called a shell or envelope, which is continuous, i.e. surrounding the entire surface of the core. According to a second variant of the invention, the composite materials in accordance with the invention include a coating, also known as a shell or envelope, which is discontinuous, i.e. discontinuously surrounding the core surface. Preferably, from 10% to 90%, more particularly from 10% to 70%, and even more particularly from 30% to 50% of the core surface is covered with the coating. According to one embodiment, the coating is a multilayer coating, i.e. comprising one or more inner layers and an outer layer, in other words several totally or partially superimposed layers, each of which may be continuous or discontinuous. In a multilayer coating, the term "inner layer" means any layer which is not an outer layer. This may be the layer directly superimposed on the core, or any intermediate layer between the core and the outer layer. In a multilayer coating, the term "outer layer" means the layer forming the last layer of the coating which is not adjacent to the core. The outer layer is separated from the core by at least one inner layer. The outer layer has no coating. In a multilayer coating formed of two layers, the inner layer is the layer adjacent to the core and the outer layer is the layer adjacent to the inner layer and not adjacent to the core. In a multilayer coating consisting of more than two layers, the inner layers are the layer adjacent to the core and the intermediate layer(s) between the layer adjacent to the core and the outer layer. The inner layer(s) forming the multilayer coating of the composite material and the single outer layer of the composite material may be formed from identical or different compounds. Each layer may consist of a single compound or a mixture of compounds. In particular, the layer(s) may extend concentrically relative to the core. In particular, the composite materials according to the invention have a double layer surrounding the core, in other words an inner layer and an outer layer. According to a preferred embodiment, the composite materials according to the invention have at least one layer, preferably comprising at least b) at least one polymer. According to a preferred embodiment, the composite materials according to the invention comprise: a core comprising at least a) at least one particle of bismuth oxycarbonate of formula (I) (BiO)2-x(CO3), and solvates thereof, such as hydrates thereof, in which -0.4 < x < 0.6, the largest mean dimension of said particles being less than 400 nm; and at least one layer continuously or discontinuously surrounding said core and comprising b) at least one polymer. Preferably, the composite materials according to the invention comprise: - a core comprising at least a) at least one particle of bismuth oxycarbonate of formula (I) (BiO)2-x(CO3), formula (I), and solvates thereof, such as hydrates thereof, in which -0.4 < x < 0.6, the largest mean dimension of said particles being less than 400 nm, - a single layer adjacent to said core and comprising b) at least one polymer. According to a particular embodiment, the composite materials according to the invention comprise: - a core comprising at least a) at least one particle of bismuth oxycarbonate of formula (I) (BiO)_2-x(CO₃), in which -0.4 < x < 0.6, the largest mean dimension of said particles being less than 400 nm, formula (I), and the solvates thereof, such as the hydrates thereof, - an inner layer adjacent to said core, comprising at least one inorganic compound c) different from said bismuth oxycarbonate particles a), - an outer layer adjacent to said inner layer and comprising b) at least one polymer. According to a particular embodiment, the composite materials according to the invention comprise: - a core comprising at least a) at least one particle of bismuth oxycarbonate of formula (I) (BiO)2-x(CO3), in which -0.4 < x < 0.6, the largest mean dimension of said particles being less than 400 nm, formula (I), and the solvates thereof, such as the hydrates thereof, - an inner layer adjacent to said core, comprising at least one inorganic compound c) different from said bismuth oxycarbonate particles a), - an outer layer adjacent to said inner layer and comprising b) at least one polymer and optionally a) at least one particle of bismuth oxycarbonate of formula (I) (BiO)_2-x(CO₃), in which -0.4 < x < 0.6, the largest mean dimension of said particles being less than 400 nm, formula (I), and the solvates thereof, such as the hydrates thereof. a) Bismuth oxycarbonate particles The bismuth oxycarbonate particles a) according to the invention are of formula (I) (BiO)2- x(CO3), and solvates thereof, such as hydrates thereof, with -0.4 < x < 0.6. The value of x may notably be determined by elemental analysis. Preferably, x is equal to 0 and the empirical formula of the bismuth oxycarbonate particles a) is (BiO)2(CO3), and solvates thereof, such as hydrates thereof. The bismuth oxycarbonate particles a) according to the invention may be crystalline or amorphous. According to one embodiment of the invention, the bismuth oxycarbonate particles a) are amorphous. According to a preferred embodiment of the invention, the bismuth oxycarbonate particles a) are crystalline. It will be appreciated that the bismuth oxycarbonate particles a) may consist of a mixture of several bismuth oxycarbonate particles having different empirical formulae and/or different shapes. Thus, the bismuth oxycarbonate particles a) may be a mixture of amorphous particles and of crystalline particles. For the purposes of the present invention, the term “crystalline” means that the atoms forming the bismuth oxycarbonate particles are arranged in an ordered manner. In other words, the crystalline bismuth oxycarbonate particles are organized materials. In contrast, “amorphous” particles are those in which the atoms are disordered. The atoms of such particles do not exhibit any organization at the microscopic level. Preferably, the crystalline particles required according to the invention have the crystal phase of the natural ore bismutite, which is referred to as lamellar, and which has alternating layers of [Bi2O2]²⁺ and [CO3]^2-. Such particles crystallize in an orthorhombic system with the space group Imm2. The bismutite crystal structure of bismuth oxycarbonate may have the following lattice parameters: a = 3.865 Å; b = 3.862 Å; c = 13.675 Å and Vlattice = 0.204 nm³. This particular arrangement of atoms notably enables the growth of anisotropic objects. A particle is considered to be “anisotropic” when the elongation factor R between the length thereof L and the thickness thereof e, i.e. R = L / e, is greater than 2. According to the invention, the largest mean dimension of the crystallized or amorphous, preferably crystallized, bismuth oxycarbonate particles a) of empirical formula (BiO)_2- x(CO3), in which -0.4 < x < 0.6, is less than 400 nm. Preferably, the largest mean dimension of said particles is less than or equal to 300 nm. According to the invention, the particles of bismuth oxycarbonate of empirical formula (BiO)2-x(CO3), in which -0.4 < x < 0.6, can be of any shape. The shape of said particles will notably depend on the process for preparing them and on the operating conditions. According to one embodiment, the particles a) are of identical morphology. In particular, when the composition comprises particles a) of identical morphology, the composite material according to the invention consists of particles in the form of platelets or sheets or rods or spheres or flowers or pompoms or threads or filaments or fibers or needles, or cubes, preferably in the form of platelets or rods. According to one embodiment, the particles a) are of different morphologies. In particular, when the composite material comprises particles a) of different morphologies, the composite material according to the invention comprises one or more particles chosen from particles in the form of tubes, platelets, sheets, rods, spheres, flowers, pompoms, threads, filaments, fibers, needles, cubes or any mixture thereof. The particles according to the invention may also aggregate in the form of superstructures. For example, platelets, tubes and/or rods can aggregate in the form of spheres, flowers or pompoms. According to a preferred embodiment, the particles according to the invention are in the form of platelets and/or rods. The particles in the form of platelets or rods or tubes thus differ notably from spherical or fibrous forms or flowers, pompoms, threads, filaments, needles or cubes. Needless to say, the particles according to the invention can be used in the form of a mixture. In particular, the particles according to the invention can be used in a mixture in any proportion of platelets and/or of rods and/or of tubes, in particular in a mixture in any proportion of platelets and/or of rods. According to a preferred embodiment, the particles used according to the invention are predominantly or exclusively in the form of platelets. A particle in “platelet” form has a length greater than the width thereof, and a width greater than the thickness thereof. In particular, when they are in the form of platelets, the bismuth oxycarbonate particles a) have: - a mean length L ranging from 15 to 300 nm, in particular ranging from 30 to 250 nm, preferably ranging from 50 to 200 nm, more preferentially ranging from 70 to 150 nm; - a mean width l ranging from 10 to 250 nm, in particular ranging from 20 to 200 nm, preferably ranging from 30 to 150 nm, more preferentially ranging from 50 to 120 nm; - a mean thickness e ranging from 2 to 120 nm, in particular ranging from 5 to 100 nm, preferably ranging from 10 to 80 nm, more preferentially ranging from 20 to 50 nm; and - with e < l < L. According to one embodiment, the bismuth oxycarbonate particles are predominantly or exclusively in the form of rods or comprise particles in the form of rods. A particle in “rod” form has a solid cylindrical form and the length thereof L is greater than the diameter thereof d, or has a prism form, the base of which is solid and polygonal, preferably triangular or hexagonal, and the diameter d of the circle within which this polygonal base is circumscribed is less than the length L of the prism. In particular, when they are in the form of rods, whether cylindrical or in the form of a prism, the bismuth oxycarbonate particles have: - a mean length L ranging from 30 to 300 nm, in particular ranging from 50 to 250 nm, preferably ranging from 70 to 230 nm, more preferentially ranging from 70 to 140 nm; - a mean diameter d ranging from 15 to 150 nm, in particular ranging from 20 to 130 nm, preferably ranging from 25 to 120 nm, more preferentially ranging from 25 to 100 nm, and even more preferentially ranging from 25 to 60 nm, and - with L > d. According to one embodiment, the bismuth oxycarbonate particles of the invention contain particles in the form of tubes. A particle in “tube” form has a hollow cylindrical form and the length thereof L is greater than the diameter thereof d. In particular, when they are in the form of tubes, the bismuth oxycarbonate particles have: - a mean length L ranging from 10 to 300 nm, in particular ranging from 20 to 250 nm, preferably ranging from 40 to 200 nm, more preferentially ranging from 60 to 200 nm; - a mean diameter d ranging from 2 to 30 nm, in particular ranging from 3 to 20 nm, and preferably ranging from 5 to 15 nm; and - with L > d. For the purposes of the present invention, “predominantly in the form of platelets/rods” is intended to denote that at least 50% by number, in particular at least 70% by number, or even at least 90% by number of the particles are in the form of platelets/rods, respectively. Doping of the particles a) According to a particular embodiment, the bismuth oxycarbonate particles a) may be doped. In particular, the bismuth oxycarbonate particles may be doped with one or more chemical elements which are capable of being inserted into the structure, or of partially replacing elements that are already present. The particles can be doped via substitutions of all or some of the cations and/or of all or some of the anions. According to a particular embodiment, doping relates in part to inserted cations or cations as substitution for the bismuth, to the limit of 20% of the composition in terms of bismuth. According to this variant, the degree of doping ranges in particular from 0.005% to 15%, preferably from 0.05% to 12%, more preferentially from 0.1% to 10%, and even more preferentially from 0.5% to 6%. In particular, the bismuth oxycarbonate particles may be doped with cations derived from elements chosen from aluminum (Al), silicon (Si), scandium (Sc), titanium (Ti), vanadium (V), manganese (Mn), iron (Fe), copper (Cu), zinc (Zn), gallium (Ga), germanium (Ge), yttrium (Y), zirconium (Zr), niobium (Nb), molybdenum (Mo), silver (Ag), indium (In), lanthanum (La), cerium (Ce), tantalum (Ta), tungsten (W) and/or gold (Au). Preferably, the bismuth oxycarbonate particles may be doped with cations derived from elements chosen from titanium, vanadium, manganese, iron, copper, zinc, lanthanum and/or cerium, more preferentially from manganese, iron and/or cerium, and even more preferentially from manganese or iron. According to one embodiment variant, the bismuth oxycarbonate particles are doped with cations derived from manganese, and the degree of doping ranges in particular from 0.5% to 2%. According to another embodiment variant, the bismuth oxycarbonate particles are doped with cations derived from iron, and the degree of doping ranges in particular from 0.5% to 2%. According to another particular embodiment, the doping relates in part or entirely to inserted anions or anions as substitution for the carbonate group, to the limit of 20% of the composition in terms of carbonate. According to this variant, the degree of doping ranges in particular from 0.001% to 1%, preferably from 0.002% to 0.5%, more preferentially from 0.003% to 0.2%, and even more preferentially from 0.005% to 0.1%. In particular, the bismuth oxycarbonate particles may be doped with anions derived from elements chosen from fluorine (F), sulfur (S), chlorine (Cl), bromine (Br), iodine (I), and/or with polyatomic anions, in particular chosen from the sulfate ion (SO₄ ^2-), the sulfonate ion (S(=O)2-O-), the sulfite ion (SO3^2-), the phosphate ion (PO4^3-) and/or the iodate ion (IO3-). Preferably, the bismuth oxycarbonate particles may be doped with S^2-, SO₃ ^2-, SO₄ ^2-, Cl- and/or I-, more preferentially with SO3^2-, SO4^2- and/or Cl-, and more preferentially with Cl- or SO4^2-. According to one embodiment variant, the bismuth oxycarbonate particles are doped with anions derived from chlorine, and the degree of doping ranges in particular from 0.01% to 0.1%. According to another embodiment variant, the bismuth oxycarbonate particles are doped with anions derived from iodine, and the degree of doping ranges in particular from 0.003% to 0.01%. According to another embodiment variant, the bismuth oxycarbonate particles are doped with the sulfate ion, and the degree of doping ranges in particular from 0.005% to 0.1%. According to another embodiment variant, the bismuth oxycarbonate particles are doped with cations, preferably derived from elements chosen from titanium, vanadium, manganese, iron, copper, zinc, lanthanum and/or cerium, more preferentially chosen from manganese, iron and/or cerium, and even more preferentially chosen from manganese or iron, and with anions, preferably derived from elements chosen from fluorine (F), sulfur (S), chlorine (Cl), bromine (Br), iodine (I), and/or with polyatomic anions, in particular chosen from the sulfate ion (SO₄ ^2-), the sulfonate ion (S(=O)₂-O-), the sulfite ion (SO₃ ^2-), the phosphate ion (PO₄ ^3-) and/or the iodate ion (IO3-), more preferentially with S^2-, SO3^2-, SO4^2-, Cl- and/or I-, even more preferentially with SO3^2-, SO4^2- and/or Cl-, and particularly preferably with Cl-, I- or SO₄ ^2-. According to a preferred embodiment, the bismuth oxycarbonate particles required according to the invention are non-doped. According to another preferred embodiment, the bismuth oxycarbonate particles required according to the invention are doped. According to another preferred embodiment, the bismuth oxycarbonate particles required according to the invention are a mixture of doped particles and of non-doped particles. Process for preparing the bismuth oxycarbonate particles a) The bismuth oxycarbonate particles a) may be obtained via any preparation process known to those skilled in art. For example, the synthesis of the bismuth oxycarbonate particles is described in the article by Ni et al. (Fabrication, modification and application of (BiO)2CO3-based photocatalysts: A review, Applied Surface Science, 365, 2016, 314–335). In particular, the bismuth oxycarbonate particles can be prepared via the solvothermal route, via the electrochemical route, by co-precipitation, or else at reflux, and preferably via the solvothermal route or at reflux. According to a first embodiment variant, the bismuth oxycarbonate particles are obtained via the solvothermal route, in particular from bismuth nitrate and various carbonating agents such as sodium carbonate, ammonium carbonate or urea, in a polar protic solvent in the presence of polyols. Such a synthesis makes it possible to obtain bismuth oxycarbonate particles in the form of platelets and/or rods, the largest dimension of which ranges from 50 to 300 nm. The solvothermal synthesis of particles is notably described in the articles by Cheng, G. et al. (Shape-controlled solvothermal synthesis of bismuth subcarbonate nanomaterials, J. Solid State Chem. 183, 1878–1883 (2010)); Ruan, M.M. et al. (Facile Green Synthesis of Highly Monodisperse Bismuth Subcarbonate Micropompons Self-assembled by Nanosheets: Improved Photocatalytic Performance, Acta Physico-Chimica Sinica, 33, 2017, 1033-1042); Quin et al. (Template‐Free Fabrication of Bi₂O₃ and (BiO)₂CO₃ Nanotubes and Their Application in Water Treatment, Chem. Eur. J., 18, 2012, 16491–16497); Cheng, G. et al. (Shape-controlled solvothermal synthesis of bismuth subcarbonate nanomaterials, J. Solid State Chem., 183, 2010, 1878–1883); Liu, Y.Y. et al. (Preparation, electronic structure, and photocatalytic properties of Bi2O2CO3 nanosheet, Appl. Surf. Sci., 257, 2010, 172–175); Zheng et al. (Synthetic Bi2O2CO3 nanostructures: Novel photocatalyst with controlled special surface exposed, Journal of Molecular Catalysis A: Chemical, 2010, 317 (1-2), 34- 40); Liu, S.Q. et al. (The effects of citrate ion on morphology and photocatalytic activity of flower-like Bi2O2CO3, Ceram. Int., 40, 2014, 2343–2348); or Chen, R. et al. (Bismuth subcarbonate nanoparticles fabricated by water-in-oil microemulsion-assisted hydrothermal process exhibit anti-Helicobacter pylori properties, Mater. Res. Bull., 45, 2010, 654–658). The electrochemical synthesis of particles is notably described in the article by Hu, Y. et al. (Simple hydrolysis route to synthesize Bi2O2CO3 nanoplate from Bi nanopowder and its photocatalytic application, Materials Letters, 170, 2016, 72–75). The synthesis of particles by co-precipitation is notably described in the article by Chen, X.Y. et al. (Controlled synthesis of bismuth oxo nanoscale crystals (BiOCl, Bi12O17Cl2, α- Bi2O3, and (BiO)2CO3) by solution-phase methods, J. Solid State Chem., 180, 2007, 2510– 2516). The synthesis of particles by reflux is notably described in the article by Chen et al. (Fabrication of bismuth subcarbonate nanotube arrays from bismuth citrate, Chem. Commun., 2006, 2265–2267). According to a preferred embodiment, the bismuth oxycarbonate particles required according to the invention are obtained via the solvothermal route, for example according to the process described by Cheng et al., or at reflux, for example according to the process described by Chen et al. According to a preferred embodiment, the bismuth oxycarbonate particles required according to the invention are obtained via a preparation process using one or more bismuth(III) complexes, one or more carbonating agents, one or more polyols and optionally one or more polar solvents other than polyols. When the particles used according to the invention are doped, one or more additional reagents including the doping elements may be added. In particular, the bismuth(III) complex(es) is (are) chosen from bismuth nitrate and the hydrated forms thereof, bismuth citrate and the hydrated forms thereof, bismuth sulfate and the hydrated forms thereof, and bismuth chloride and the hydrated forms thereof. The bismuth(III) complex(es) may also be obtained from bismuth minerals, such as elemental bismuth and/or bismuth oxide and/or bismuth sulfide. Preferably, the bismuth(III) complex(es) is (are) bismuth(III) nitrate and the hydrated forms thereof of formula Bi(NO₃)₃·xH₂O, and is preferably bismuth nitrate pentahydrate of formula Bi(NO3)3·5H2O. In particular, the carbonating agent(s) is (are) chosen from Li2CO3, Na2CO3, K2CO3, Rb₂CO₃, Cs₂CO₃, (NH₄)₂CO₃, LiHCO₃, NaHCO₃, KHCO₃, RbHCO₃, CsHCO₃, (NH₄)HCO₃, urea (NH₂)₂CO and urea derivatives, CO₂, preferably from Na₂CO₃, K₂CO₃, (NH2)2CO, (NH4)2CO3, and more preferentially from (NH2)2CO and/or (NH4)2CO3. Polyols are compounds containing a plurality of hydroxyl functions. They may in particular be chosen from glycols, in particular ethylene glycol, propylene glycol, butylene glycol, pentylene glycol, hexylene glycol; short- or long-chain glycol polymers, for example polyethylene glycol, polypropylene glycol, polybutylene glycol; glycerol and derivatives thereof, or for example sugars, in particular glucose, fructose, sucrose, xylitol, mannitol, such as D-mannitol, sorbitol or maltitol. According to one embodiment, the bismuth oxycarbonate particles required according to the invention are obtained via a preparation process using a polyol or a mixture of polyols. According to a first embodiment variant, the polyol(s) may also be used as solvent. The bismuth oxycarbonate particles can then be obtained, for example, according to the process described below. A solution A is formed from the dissolution of the bismuth(III) complex, preferably at a concentration of 0.001 to 0.5 M, in the polyol or mixture of polyols. A solution B is formed by the partial or full dissolution of the carbonating agent, preferably from 1 to 100 equivalents relative to the bismuth, in the polyol or mixture of polyols or in a polyol or mixture of polyols other than that (those) used in solution A. In the case of doping with a cation, the dopant is preferably integrated into solution A. In the case of doping with an anion, the dopant is preferably integrated into solution B. In the case of doping with one or more cations and/or with one or more anions, the cationic dopant(s) is/are preferably integrated into solution A and the anionic dopant(s) is/are preferably integrated into solution B. Solution A is subsequently added to solution B at room temperature. If the polyol or mixture of polyols is not liquid at room temperature, all the solids are mixed. The mixture obtained is then heated at between 90 and 250 °C for a reaction time of between 10 minutes and 48 hours. If the desired reaction temperature is greater than or equal to the boiling point of the solvent, solvothermal synthesis is performed using an autoclave. Preferably, the reaction temperature is between 95 °C and 200 °C and the reaction time is between 1 and 24 hours, and more preferentially the reaction temperature is between 100 °C and 180 °C and the reaction time is between 2 and 16 hours. The particles obtained are isolated from the reaction medium by centrifugation and washed by successive cycles of dispersion and centrifugation. After drying under vacuum at a temperature of between 40 °C and 60 °C, a white powder is obtained. In the case in which the polyol(s) are used as solvents, the bismuth oxycarbonate particles obtained are in the form of platelets, preferably with a mean thickness e of between 2 and 15 nm, and/or in the form of tubes. According to another embodiment variant, the polyol(s) are used solely as additives and not as solvent. The bismuth oxycarbonate particles can then be obtained, for example, according to the process described below. A solution A is formed from the dissolution of the bismuth complex, preferably at a concentration from 0.001 to 0.5 M, and of the polyol(s), preferably at a total concentration of polyols preferably from 0.01 to 5 M, in a solvent, preferably a polar solvent. A solution B is formed from the partial or full dissolution of the carbonating agent, preferably from 1 to 100 equivalents relative to the bismuth complex, in the polar solvent (miscible with the solvent from A) which is identical to or different from, preferably identical to, that of solution A. In the case of doping with a cation, the dopant is preferably integrated into solution A. In the case of doping with an anion, the dopant is preferably integrated into solution B. In the case of doping with one or more cation(s) and/or with one or more anion(s), the cationic dopant(s) is/are preferably integrated into solution A and the anionic dopant(s) is/are preferably integrated into solution B. Solution A is then added to solution B at room temperature. The mixture obtained is then heated at between 90 °C and 250 °C for 10 minutes to 48 hours. If the desired reaction temperature is greater than or equal to the boiling point of the solvent, solvothermal synthesis is performed using an autoclave. Preferably, the reaction temperature is between 90 °C and 150 °C and the reaction time is between 4 and 16 hours. The particles obtained are isolated from the reaction medium by centrifugation and washed by successive cycles of dispersion and centrifugation. After drying under vacuum at a temperature of between 40 °C and 60 °C, a white powder is obtained. When the polyol(s) are used solely as additives, they may in particular be chosen from ethylene glycol, propylene glycol, glycerol and/or a sugar, preferably a sugar, more preferentially D-mannitol. According to this variant, the synthetics process also uses a solvent different from the polyols, or a mixture of solvents other than the polyols. In particular, the solvent or mixture of solvents is chosen from polar solvents, preferably from polar and protic solvents, such as water, C₁-C₆ alcohols such as ethanol or isopropanol, and mixtures thereof, and the solvent is even more preferentially water. In particular, when the polyol(s) are chosen solely as additives and the water as solvent, the bismuth oxycarbonate particles are preferably obtained in the form of platelets and/or in the form of rods. Polymer b) The composite materials according to the invention comprise at least one polymer b). The polymer(s) b) are natural and/or synthetic, hydrophilic and/or hydrophobic and/or amphiphilic, anionic and/or cationic and/or zwitterionic and/or nonionic (or referred to as “neutral”). Preferably, the polymer(s) b) is (are) nonionic, anionic or cationic, more preferentially nonionic or anionic. In particular, the polymer(s) b) are chosen from polymers having a molecular weight of between 1000 and 20000000 Da, preferentially between 5000 and 10000000 Da and even more preferentially between 7000 and 3000000 Da. The polymer(s) b) are in crosslinked and/or non-crosslinked form, preferably non- crosslinked. The polymer(s) b) may be silicone polymers or non-silicone polymers. According to a particular embodiment, the polymer(s) b) are or comprise at least one silicone polymer. As examples of silicone polymers b), mention may be made of dimethicone copolyols, in particular the mixture of cyclomethicone and dimethicone copolyol, notably sold under the name DC 5225 C^® by the company Dow Corning, and alkyldimethicone copolyols, in particular laurylmethicone copolyol, notably sold under the name Dow Corning 5200 Formulation Aid by the company Dow Corning, cetyl dimethicone copolyol and the mixture of cetyl dimethicone copolyol, polyglycerol (4 mol) isostearate and hexyl laurate. According to a preferred embodiment, the polymer(s) b) contain no silicon atoms. According to a preferred embodiment, the weight-average molar mass Mw of the polymers(s) b) is greater than or equal to 2000. The term "anionic polymer" means a polymer containing one or more anionic groups, in particular carboxyls, carboxylates, sulfates, sulfonic acids, sulfonates, phosphates, phosphonic acids, phosphonates, preferably chosen from carboxylates and/or sulfonates and/or sulfates. The anionic derivatives may be salified in the form of alkali metal or alkaline-earth metal salts, preferably of sodium or calcium. The term "cationic polymer" means a polymer containing one or more cationic groups, which bear a charge irrespective of the pH, or which are cationizable. Preferably, the cationic polymers b) bear amino groups. The term "nonionic polymer" means a polymer which does not bear any charged groups or groups which can be charged by varying the pH. In particular, the polymer(s) b) can be chosen from polyphenols and salts thereof, polyphenol sulfonates and salts thereof, polysaccharides and salts thereof, polyacids and salts thereof, polyols, polyamides, polyamines and salts thereof, polyesters, polyhydroxyalkanoates, polyureas, polyurethanes, polyethers, polyethylenes, polypropylenes, polystyrenes, proteins, and/or copolymers thereof and/or mixtures thereof. The polymer(s) b) are cyclic or acyclic (not containing any rings in their structure). The cyclic polymer(s) b) may be aromatic (containing at least one aromatic ring) or non- aromatic. Examples of aromatic cyclic polymers b) include lignosulfonic acid, lignosulfonates, sulfonic polystyrenes, polystyrene sulfonates, anionic polyanethole derivatives, in particular polyanethole sulfonates, and mixtures thereof. According to a particular embodiment, said polymer(s) b) are chosen from sulfonic polystyrenes, polystyrene sulfonates, notably polystyrene sulfonates of alkali metal or alkaline-earth metal salts, notably of sodium or calcium. According to one embodiment, said polymer(s) b) are chosen from lignosulfonic acids or lignosulfonate salts of alkali metals or alkaline-earth metals, in particular of sodium or calcium. According to one embodiment, said polymer(s) b) are chosen from anionic polyanethole derivatives, in particular polyanethole sulfonates of alkali metals or alkaline-earth metals, notably of sodium or calcium, in particular of sodium. Preferably, the non-aromatic cyclic polymer(s) b) are chosen from polysaccharides, these polysaccharides possibly being anionic, cationic or nonionic. Preferably, the polymer(s) b) are chosen from natural hydrophilic and/or lipophilic and/or amphiphilic and anionic and/or cationic and/or neutral polysaccharides. More preferentially, the polymer(s) used are natural hydrophilic and/or lipophilic and/or amphiphilic and anionic and/or cationic and/or neutral polysaccharides, and notably natural hydrophilic anionic and/or cationic and/or neutral polysaccharides. More preferentially, the polymer(s) used is (are) neutral or anionic polysaccharides. As non-limiting representatives of these polysaccharides, mention may notably be made of carrageenans, chitosan, dextran sulfates, (di)starch phosphate, pullulans and the forms thereof esterified (or acetylated) by a carboxylic acid, preferably comprising from 1 to 30 carbon atoms, more particularly from 8 to 20 carbon atoms, such as myristoyl pullulan and ulvan. According to a particular embodiment, the polymer(s) b) of the invention represent a mixture of polymers b), one of which is a polysaccharide or a salt thereof, the α or β anomers thereof, the L- or D-configuration optical isomers thereof and the solvates thereof, such as the hydrates thereof. According to a particular embodiment, the polymer(s) b) of the invention represent a single polysaccharide or a salt thereof, the α or β anomers thereof, the L- or D-configuration optical isomers thereof and the solvates thereof, such as the hydrates thereof. In particular, the non-aromatic cyclic polymers b) are chosen from anionic polysaccharides and are chosen from sulfated polysaccharides, phosphated polysaccharides and polysaccharide carboxylates. The polysaccharide may optionally be acetylated. The degree of acetylation may range from 1% to 40% by weight (weight content of acetyl units relative to the total weight of the polymer). According to a preferred embodiment, the polymer b) is chosen from polysaccharides having a weight-average molecular weight ranging from 1000 to 20000000 Da, preferentially from 5000 to 10000000 Da and even more preferentially from 7000 to 3000000 Da. Among the phosphated polysaccharides, mention may be made of phosphated starches, such as hydroxypropyl corn distarch phosphate. Among the sulfated polysaccharides, mention may be made of ulvans, dextran sulfates, carrageenans, in particular lambda carrageenan, fucoidans, ulvans, dextran sulfates and mixtures thereof. Advantageously, the degree of polysaccharide sulfation may range from 1% to 90% by weight, relative to the weight of the polysaccharide(s). Preferably, this degree of sulfation may range from 2% to 85% by weight. In particular, the sulfated polysaccharides b) may also be chosen from ulvans, which are sulfated polysaccharides derived from algae, notably red or green algae. Ulvans may be obtained from numerous species of ulva, among which mention may be made of Ulva lactuca, Ulva rigida, Ulva armoricana, Ulva rotundata and Ulvaria obscura, and several species of enteromorphs, in particular Enteromorpha compressa, Enteromorpha intestinalis and Enteromorpha ramulosa. Ulvans comprise mainly rhamnose, glucuronic acid, glucose, galactose and xylose, and comprise sulfate groups. They may also comprise varying amounts of galacturonic acid, iduronic acid and mannose. Ulvans generally have a degree of polysaccharide sulfation ranging from 1% to 30% by weight, relative to the weight of the polysaccharide, and more particularly from 10% to 20% by weight. The relative proportion of sugars of the ulvans varies according to the ulva harvesting location, the species and the harvesting time of year. For the production of ulvans by extraction from ulva, reference may be made to the extraction processes described in Carbohydrate Research 274 (1995) 251-261 or in Hydrobiologia 326/327; 473-480, 1996. According to a particular embodiment, the polymer(s) b) are or contain at least one ulvan. In particular, the sulfated polysaccharides b) may also be chosen from dextran-derived dextran sulfates. Dextran is a complex branched glucan (polysaccharide derived from glucose condensation), originally derived from wine. The IUPAC defines dextrans as "branched poly-α-D- glucosides of microbial origin whose glycosidic linkages are predominantly C-1 → C-6". Dextran chains vary in length (from 3 to 2000 kilodaltons). The main polymer chain consists of α-1,6 glycosidic linkages between glucose monomers, with branches of α-1,3 linkages. This characteristic branching distinguishes a dextran from a dextrin, which is a straight-chain glucose polymer linked by α-1,4 or α-1,6 linkages. Use may notably be made of the dextran sulfate sold under the trade name Dextran Sulfate 10 Sodium Salt CG, by the company PK Chemicals. Among the polysaccharide carboxylates b), mention may be made of alginates. Alginates are obtained from brown algae such as kelp or bladderwrack. Alginates are preferably sodium alginates or calcium alginates. Alginates are polysaccharides derived from mannuronate or mannuronic acid, some of which are optionally acetylated, and guluronate or guluronic acid. The linkage is of beta 1-4 type. According to a particular embodiment, the polymer(s) b) of the invention are chosen from nonionic polymers, in particular nonionic polysaccharides. As examples of nonionic polysaccharides, mention may be made of starches and pullulan, in particular pullulan. According to one embodiment, the polymer(s) b) according to the invention are chosen from nonionic polymers, in particular nonionic polysaccharides, and more particularly polysaccharides modified by the presence of at least one aliphatic, cyclic or non-cyclic, linear or branched, saturated or unsaturated, aromatic or non-aromatic hydrocarbon-based chain comprising from 2 to 30 carbon atoms, optionally substituted with one or more atoms or groups from among a) halogen, such as chlorine or bromine, b) (hetero)aryl, such as phenyl or furyl, c) (hetero)cycloalkyl, such as anhydride, epoxide or dithiolane, d) R-X with R representing a group chosen from i) cycloalkyl such as cyclohexyl, and/or ii) (di)alkylamino and/or optionally interrupted with one or more heteroatoms or groups chosen from a') heteroatoms, such as O, S, N(Ra), and Si(Rb)(Rc), b') S(O)r, (thio)carbonyl, c') or combinations of a') with b'), such as (thio)ester, (thio)amide, (thio)urea, sulfonamide with r being 1 or 2, Ra representing a hydrogen atom, or a (C1-C4)alkyl, or aryl(C1-C4)alkyl group, such as benzyl, preferably Ra represents a hydrogen atom, and Rb and Rc, which may be identical or different, represent a (C1-C4)alkyl or (C1-C4)alkoxy group. As modified polysaccharides, mention may notably be made of those obtained from native gums, such as those derived from tree or shrub exudates, algae, seeds or tubers, fungi, bacteria, animal organisms or plants, which have been modified physically, by chemical reaction or enzymatically. In particular, the native gums may be chosen from: - gum arabic (branched polysaccharide of galactose, arabinose, rhamnose and glucuronic acid); - ghatti gum (polymer derived from arabinose, galactose, mannose, xylose and glucuronic acid); - karaya gum (polymer derived from galacturonic acid, galactose, rhamnose and glucuronic acid); - gum tragacanth (polymer of galacturonic acid, galactose, fucose, xylose and arabinose); - agar (polymer derived from galactose and anhydrogalactose); - alginates (polymers of mannuronic acid and of glucuronic acid); - carrageenans and furcellerans (polymers of galactose sulfate and of anhydrogalactose sulfate); - guar gum (polymer of mannose and galactose); - locust bean gum (polymer of mannose and galactose); - fenugreek gum (polymer of mannose and galactose); - tamarind gum (polymer of galactose, xylose and glucose); - konjac gum (polymer of glucose and mannose); - xanthan gum (polymer of glucose, mannose acetate, mannose/pyruvic acid and glucuronic acid) or dehydroxanthan gum; - gellan gum (polymer of partially acylated glucose, rhamnose and glucuronic acid); - scleroglucan gum (glucose polymer); - cellulose (glucose polymer); - starch (glucose polymer); - inulin; and - pectin. In particular, the modified polysaccharides are derived from: i) gum arabic; ii) ghatti gum; iii) karaya gum; iv) gum tragacanth; v) agar; vi) alginates; vii) carrageenans and furcellerans; viii) guar gum; ix) locust bean gum; x) fenugreek gum; xi) tamarind gum; xii) konjac gum; xiii) xanthan gum or dehydroxanthan gum; xiv) gellan gum; xv) scleroglucan gum; xvi) cellulose; xvii) starch; xviii) inulin; and xix) pectin. The botanical origin of the starch molecules xvii) may be cereals or tubers. Thus, the starches are chosen, for example, from corn starch, rice starch, cassava starch, barley starch, potato starch, wheat starch, sorghum starch and pea starch. The starches may be chemically or physically modified, notably by one or more of the following reactions: pregelatinization, oxidation, crosslinking, esterification, etherification, amidation, heat treatments. The nonionic modified polysaccharides may be physically or chemically modified. A physical treatment that may notably be mentioned is the temperature. Chemical treatments that may be mentioned include esterification, etherification, amidation, oxidation, metathesis and addition reactions. According to a particular embodiment, the modified polysaccharides are polysaccharide ethers known as alkyl polysaccharides, the alkyl radical of which comprises between 2 and 30 carbon atoms, preferably between 2 and 10 carbon atoms, more preferentially between 2 and 6 carbon atoms. Preferably, the alkyl polysaccharides according to the invention are derived from cellulose or guar or mixtures thereof. According to a particular embodiment, the modified polysaccharides are alkylcelluloses, the linear or branched alkyl residue of which comprises between 1 and 10 carbon atoms, in particular between 2 and 6 carbon atoms, preferably between 2 and 3 carbon atoms. The alkylcellulose is a cellulose alkyl ether comprising a chain formed from β- anhydroglucose units linked together via acetal bonds. Each anhydroglucose unit exhibits three replaceable hydroxyl groups, it being possible for all or some of these hydroxyl groups to react according to the following reaction: Cell- OR + MHal with Hal representing a halogen, such as Cl, with M representing a cationic counterion, such as an alkali metal Na or K, or an alkaline-earth metal, preferably an alkali metal, such as Na, Cell representing a polysaccharide radical, such as cellulose, where R represents a linear or branched alkyl group comprising from 1 to 10 carbon atoms, preferably between 2 and 3 carbon atoms, such as methyl or ethyl, and MHal the salt generated, such as sodium chloride. Advantageously, the alkyl cellulose is chosen from ethyl cellulose and propyl cellulose. According to a particular embodiment, the polysaccharide ethers are alkyl guars, in other words guar gums viii) modified by substitution of the hydroxyl hydrogen with a linear or branched alkyl group, comprising between 1 and 10 carbon atoms, in particular between 2 and 6 carbon atoms, preferably between 2 and 3 carbon atoms, such as 2 carbon atoms. The alkyl guar polymers used according to the invention are preferentially ethyl guar. Ethyl guar is known under the INCI name: C1-C5 alkyl galactomannan. Alkylated guar gums (with C₁-C₆ alkyl group), including ethyl guar, are notably described in patent application EP 708114 and document RD9537807 (October 1995), as is the process for preparing same. According to a particular embodiment, the modified polysaccharides are polysaccharide esters, in particular esters obtained by reaction between at least one polysaccharide such as dextrin with at least one saturated or unsaturated linear or branched acid including from 2 to 30 carbon atoms, notably from 10 to 30 carbon atoms. According to a particular embodiment of the invention, the modified polysaccharide(s) are chosen from polysaccharide mono- or polyalkyl esters. Among the saccharide or polysaccharide monoalkyl or polyalkyl esters that are suitable for use in the invention, mention may be made of dextrin or inulin alkyl or polyalkyl esters. It may notably be a mono- or poly-ester of dextrin (dextrin being derived from starch xvii) and of at least one fatty acid (such as R-C(O)-OH) and notably corresponding to formula (XVIII) below: [Chem 1] in which formula (XVIII): - n is an integer greater than or equal to 2, preferably ranging from 3 to 200, notably ranging from 20 to 150 and in particular ranging from 25 to 50, - R1, R2 and R3, which may be identical or different, are chosen from hydrogen or an acyl group (R-C(O)-) in which the radical R is a linear or branched, saturated or unsaturated hydrocarbon-based group containing from 7 to 29, in particular from 7 to 21, notably from 11 to 19, more particularly from 13 to 17, or even 15, carbon atoms, wherein at least one of said radicals R1, R2 or R3 is other than hydrogen. In particular, R₁, R₂ and R₃ represent a hydrogen atom or an acyl group (R-C(O)-) in which R is a hydrocarbon-based radical as defined previously, with the proviso that at least two of said radicals R1, R2 or R3 are other than hydrogen. All the radicals R₁, R₂ and R₃ may represent an identical or different acyl group (R-C(O)), and the acyl groups are notably identical. In particular, n mentioned above advantageously ranges from 25 to 50 and is notably equal to 38 in the general formula of the saccharide ester that may be used in the present invention. Notably, when the radicals R₁, R₂ and/or R₃, which may be identical or different, represent an acyl group (R-C(O)), derived from a fatty carboxylic acid R-C(O)OH, said carboxylic acid is preferably chosen from caprylic, capric, lauric, myristic, palmitic, stearic, arachic, behenic, isobutyric, isovaleric, 2-ethylbutyric, ethylmethylacetic, isoheptanoic, 2- ethylhexanoic, isononanoic, isodecanoic, isotridecanoic, isomyristic, isopalmitic, isostearic, isoarachic, isohexanoic, decenoic, dodecenoic, tetradecenoic, myristoleic, hexadecenoic, palmitoleic, oleic, elaidic, asclepinic, gondoleic, eicosenoic, sorbic, linoleic, linolenic, punicic, stearidonic, arachidonic and stearolic acids, and mixtures thereof. Preferably, at least one dextrin palmitate is used as fatty acid ester of dextrin. This ester may be used alone or as a mixture with other esters. Preferably, the fatty acid ester of dextrin has a degree of substitution of less than or equal to 2.5, notably ranging from 1.5 to 2.5 and preferably from 2 to 2.5 on the basis of one glucose unit. The weight-average molecular weight of the dextrin ester may in particular be from 10000 to 150000 Da, notably from 12000 to 100000 Da, and even from 15000 to 80000 Da. Preferably, the modified polysaccharide(s) of the invention are dextrin esters, more preferentially dextrin palmitates. Dextrin esters, in particular dextrin palmitates, are commercially available under the name Rheopearl KL2^®, MKL2^®, TL^® or KL^® from the company Chiba Flour. According to a particular embodiment, the modified polysaccharide is a modified dextrin, preferably a dextrin ester, more particularly a saturated or unsaturated, linear or branched C12-C24 fatty acid ester of dextrin. Preferably, the dextrin ester is chosen from esters of saturated or unsaturated, linear or branched C₁₄-C₂₄ fatty acids, such as myristic acid, palmitic acid or a mixture thereof. According to a particular embodiment, the dextrin ester is chosen from dextrin palmitates such as Rheopearl KL2^® and Rheopearl TL2^®, sold by Chiba Flour, and dextrin myristate, such as the product sold under the reference Rheopearl MKL2^® by Chiba Flour, dextrin palmitate/ethylhexanoate sold under the reference Rheopearl TT2^®, dextrin palmitate/hexyldecanoate sold under the reference Rheopearl WX, or mixtures thereof. According to a particular embodiment, the modified polysaccharide is a modified inulin, preferably an inulin ester, more particularly an ester of inulin and of a saturated or unsaturated, linear or branched C₁₂-C₂₄ fatty acid. Preferably, the inulin ester is chosen from esters of saturated or unsaturated, linear or branched C14-C24 fatty acids, such as myristic acid, palmitic acid or stearic acid, preferably stearic acid, or mixtures thereof. According to a particular embodiment, the inulin ester is a stearoyl inulin, such as the references Rheopearl ISK2^® and Rheopearl ISL2^®, sold by Chiba Flour, or mixtures thereof. According to one embodiment, the modified polysaccharide is a modified cellulose, preferably a cellulose ester, more particularly an ester of cellulose and of a saturated or unsaturated, linear or branched C2-C24 acid. Preferably, the cellulose ester is chosen from esters of saturated or unsaturated, linear or branched C₂-C₁₀, preferably C₂-C₆, notably C₂-C₄ acids, such as acetic acid, butyric acid or a mixture thereof. According to a particular embodiment, the cellulose ester is cellulose acetate butyrate, such as the reference Eastman Cellulose Acetate Butyrate^®, sold by Eastman Chemical. According to a particular embodiment, the polymer(s) b) are chosen from nonionic polymers, in particular nonionic polysaccharides, more particularly inulins modified with hydrophobic chains, such as alkylcarbamate groups, in particular C₈-C₁₈ alkyl carbamate, and more particularly laurylcarbamate. As examples of such compounds, mention may notably be made of the product sold under the name Inutec SL1 by the company Creachem. Among the polysaccharide esters, mention may also be made of pullulan esters. Pullulan is a polysaccharide consisting of maltotriose units. According to one embodiment, the modified polysaccharides are polysaccharide esters. The term "polysaccharide esters" means polysaccharides in which at least one of the hydroxyl radicals is esterified with an acid to form ester groups -O-C(O)-R or -C(O)-OR, in which R denotes a saturated or unsaturated radical of 2 to 30 carbon atoms, notably 11 to 19 carbon atoms, preferably 12 to 17 carbon atoms, such as 13 carbon atoms. In particular, the polysaccharide ester is myristoyl pullulan. According to a particular embodiment, the polymer(s) b) comprise at least one cationic modified polysaccharide. Preferably, the chemical or physical treatments to obtain at least one cationic group are applied to guar gums, locust bean gums, starches and celluloses. The cationic groups may be of the primary, secondary, tertiary or quaternary amine type, preferably quaternary, and include a C6-C30 aliphatic chain. According to a particular embodiment, the modified polysaccharide(s) b) are chosen from quaternized (poly)hydroxyethylcelluloses modified with groups including at least one aliphatic chain (or fatty chain), such as alkyl, arylalkyl, alkylaryl groups including at least 8 carbon atoms, or mixtures thereof. The alkyl radicals borne by the quaternized celluloses or hydroxyethylcelluloses preferably include from 8 to 30 carbon atoms. The aryl radicals preferably denote phenyl, benzyl, naphthyl or anthryl groups. Examples of quaternized alkylhydroxyethylcelluloses containing C₈-C₃₀ fatty chains that may be indicated include the products Quatrisoft LM 200^®, Quatrisoft LM-X 529-18-A^®, Quatrisoft LM-X 529-18-B^® (C12 alkyl) and Quatrisoft LM-X 529-8^® (C18 alkyl) sold by the company Dow Corning, and the products Crodacel QM^®, Crodacel QL^® (C12 alkyl) and Crodacel QS^® (C₁₈ alkyl) sold by the company Croda and the product Softcat SL 100^® sold by the company Dow Corning. According to a particular embodiment, the modified polysaccharide(s) b) are chosen from guar gums modified with C₁-C₂₀ (poly)hydroxylalkylammonium groups, preferably C₁-C₆ (poly)hydroxyalkyl groups. By way of example, mention may notably be made of hydroxymethyltrimmonium, hydroxyethyltrimmonium, hydroxypropyltrimmonium and hydroxybutyltrimmonium halide groups, preferably hydroxypropyltrimonium halide, preferably chloride. Such cationic guar gums modified with hydroxyalkylammonium groups are sold, for example, by the company Solvay under the trade names Cationic Jaguar^® C-14S Guar Hydroxypropyltrimonium Chloride, F Jaguar^® C-13S Guar Hydroxypropyltrimonium Chloride, F Jaguar^® C-17 Guar Hydroxypropyltrimonium Chloride, Jaguar^® Excel Guar Hydroxypropyltrimonium Chloride, Jaguar^® C-500 STD Guar Hydroxypropyltrimonium Chloride, Jaguar^® C-162 Hydroxypropyl Guar Hydroxypropyltrimonium Chloride, Jaguar^® Optima Guar Hydroxypropyltrimonium Chloride, and Jaguar^® LS Hydroxypropyl Guar Hydroxypropyltrimonium Chloride. According to a particular embodiment, the cationic non-aromatic cyclic polymers b) are in particular polysaccharides bearing amine groups, such as chitosans. Preferably, the amine groups are primary, secondary or tertiary amines, preferably primary. The term "polysaccharides bearing amine groups" also means the organic or mineral acid salts thereof, the α or β anomers thereof, the L- or D-configuration optical isomers thereof and the solvates thereof, such as the hydrates thereof. According to a particular embodiment, the polysaccharide(s) bearing amine group(s) is (are) chosen from those bearing C5-C7 saccharide units, and the organic or mineral acid salts thereof, the α or β anomers thereof, the L- or D-configuration optical isomers thereof and the solvates thereof, such as the hydrates thereof. More particularly, the polysaccharide(s) bearing amine group(s) contain(s) a C₆ saccharide unit bearing amine group(s); these polysaccharides bearing amine group(s) are then referred to as polyhexosamines. According to a particular embodiment, the saccharide units of the polysaccharide bearing amine group(s) are of β (beta) anomeric configuration and/or D configuration. According to a particular embodiment, the saccharide units of the polysaccharide bearing amine group(s) are linked together between the C1 carbon atom of one saccharide unit and the C4 carbon atom of the other saccharide unit, denoted (1→4), such as the polysaccharide bearing amine group(s) of formula (B) below, and the organic or mineral acid salts thereof, the α or β anomers thereof, the L- or D-configuration optical isomers thereof and the solvates thereof, such as the hydrates thereof: [Chem 2] in which formula (B): - the radicals Ra, Rb and Rc of each saccharide unit may be identical or different; - n is an integer greater than or equal to 2, particularly between 3 and 3000 inclusive; - R_a, R_b, and R_c, which may be identical or different, represent i) a hydroxyl group, ii) a (C₁- C₄)alkoxy group, the alkyl group of which may be optionally substituted, notably with one or more hydroxyl groups, iii) a carboxyl group, and iv) a group NR1R2 group, with R1 and R2 as defined previously, in particular R1 and R2 are chosen from a hydrogen atom and - C(O)-R’1 in which R'1 is as defined previously; preferably, R₁ and R₂ represent i) a hydrogen atom or ii) –C(O)-R'1 with R'1 representing a (C1-C4)alkyl group such as methyl; wherein at least one of the radicals Ra, Rb or Rc of at least one saccharide unit represents a group NR₁R₂ and that at least one of the groups NR₁R₂ of at least one saccharide unit represents an NH2 group; preferably, Ra of at least one saccharide unit represents a group NR1R2 with R1 which represents a hydrogen atom and R2 is chosen from i) a hydrogen atom or ii) a group –C(O)-R’1, and R_b and R_c represent a hydroxyl group, wherein at least one of the groups NR₁R₂ of at least one saccharide unit represents an NH₂ group. More particularly, the polysaccharide(s) bearing amine group(s) of the invention is (are) of formula (B1) below, and the organic or mineral acid salts thereof, the α or β anomers thereof, the L- or D-configuration optical isomers thereof, and the solvates thereof, such as the hydrates thereof: [Chem 3] in which formula (B1): - R’ represents a hydrogen atom or a (C₁-C₄)alkylcarbonyl group such as acetyl CH₃-C(O)- ; - R’’ represents a hydrogen atom or a (C₁-C₄)alkyl group optionally substituted with a carboxyl group such as –CH(CO₂H)-CH₃; - n is an integer greater than or equal to 2, particularly between 3 and 3000 inclusive; wherein, in the polysaccharide (B1), at least one saccharide unit bears an NH2 amino group and at least one other saccharide unit bears at least one group N(H)-R' with R' representing a (C1-C4)alkylcarbonyl group such as acetyl CH3-C(O)-. Preferably, the saccharide units of formula (B) or (B1) are of D configuration, also referred to as D-glucopyran. Particularly, the units of formula (B) or (B1) are of β (beta) anomeric configuration. According to a particular embodiment, the polysaccharides of the invention are chosen from the compounds of formula (B2) below, and the organic or mineral acid salts thereof, and the solvates thereof, such as the hydrates thereof: [Chem 4] in which formula (B2): - Ra, Rb and Rc are as defined for (B) previously; - the radicals R_a, R_b and R_c of each saccharide unit may be identical or different; - n is an integer greater than or equal to 2, particularly between 3 and 3000 inclusive, and more particularly between 5 and 2500, preferentially between 10 and 2300; wherein, in the polysaccharide (B2), at least one of the radicals R_a, R_b or R_c of at least one saccharide unit represents a group NR₁R₂ and that at least one of the groups NR₁R₂ of at least one saccharide unit represents an NH2 group; preferably, at least one saccharide unit bears a group R_a which represents an amino NH₂ and at least one other saccharide unit bears a group R_a which represents -N(H)-R' with R' representing a (C₁-C₄)alkylcarbonyl group such as acetyl CH3-C(O)-. Preferentially, the polysaccharide(s) bearing amine group(s) is (are) chosen from chitin and chitosan and derivatives thereof, preferably chitosan. More particularly, the polysaccharide(s) bearing amine group(s) is (are) chosen from those of formula (B3) below, and the organic or mineral acid salts thereof, and the solvates thereof, such as the hydrates thereof: [Chem 5] in which formula (B3): - R1 and R2 are as defined in formula (B), (B1) or (B2); and - n is an integer greater than or equal to 2, particularly between 3 and 3000 inclusive, and more particularly between 5 and 2500, preferentially between 10 and 2300; wherein, in the polysaccharide of formula (B3), at least one saccharide unit bears an amino group NH2 and at least one other saccharide unit bears a group N(H)-R' with R' representing a (C₁-C₄)alkylcarbonyl group such as acetyl CH₃-C(O)-. More particularly, the polysaccharide(s) bearing amine group(s) of the invention is (are) chosen from the chitosans of formula (B4) below, and the organic or mineral acid salts thereof, and the solvates thereof, such as the hydrates thereof: in which formula (B4): - R’1 represents a (C1-C4)alkyl group such as methyl; - n is an integer greater than or equal to 2, particularly between 3 and 3000 inclusive; - p is greater than 0 and ranges up to 0.5, preferably from 0.05 to 0.3, and better still from 0.1 to 0.20 such as 0.15, with m+p being equal to 1; wherein, in the chitosan, at least one saccharide unit bears an amino group NH₂ and at least one other saccharide unit bears a group N(H)-R’₁ with R' representing a (C₁- C4)alkylcarbonyl group such as acetyl CH3-C(O)-. For example, when m = 0.7 and p = 0.3, this means that 70% of the amine groups are free (unsubstituted) and 30% of the amino groups are N-(C₁-C₄)alkylcarbonyl groups, in particular N-acetyl groups, corresponding to the chitosan polymer of formula: [Chem 7] with n as defined previously. Particularly, the polysaccharide(s) bearing amine group(s) of the invention is (are) chosen from chitosans, salified using organic acid, preferentially using monocarboxylic acid of formula (I) as defined below or polycarboxylic acid of formula (II) as defined below, even more preferentially salified using carboxylic acid of formula (I) such as lactic acid. Formula (I) is represented by the formula R-C(O)-OH, with R representing a (hetero)aryl group such as phenyl, a (hetero)aryl(C1-C4)alkyl group such as benzyl, or (C1-C30)alkyl group or an unsaturated C2-C30 radical (i.e. including at least one ethylenic unsaturation, preferably one ethylenic unsaturation), said alkyl group or unsaturated C₂-C₃₀ radical being optionally interrupted and/or optionally substituted preferably with one or more hydroxyl groups and not substituted with one or more amino radicals, R preferably denoting a (C1- C6)alkyl group optionally interrupted and/or optionally substituted with 1, 2 or 3 hydroxyl groups; preferentially, R represents a (C₁-C₄)alkyl group such as methyl or ethyl; in particular, the organic monocarboxylic acids (I) are chosen from acetic acid, glycolic acid and lactic acid, more particularly from acetic acid and lactic acid, and the polycarboxylic acids of formula (II) below: in which formula (II) A represents a saturated or unsaturated, cyclic or non-cyclic, aromatic or non-aromatic polyvalent hydrocarbon-based group comprising from 1 to 30 carbon atoms, optionally interrupted with one or more heteroatoms such as oxygen and/or optionally substituted notably with one or more hydroxyl groups; and t represents an integer between 1 and 5 inclusive. Preferably, A represents a divalent (C1-C6)alkylene group optionally substituted notably with one or more hydroxyl groups and not substituted with at least one amino radical, and t is 1, 2 or 3. Preferably, the polycarboxylic acids of formula (II) are chosen from tartaric acid, succinic acid, fumaric acid and citric acid, and more particularly chosen from tartaric acid, succinic acid and fumaric acid, and citric acid, and amino acids including more carboxylic acid radicals than amino groups, such as gamma-carboxyglutamic acid, aspartic acid, glutamic acid, in particular gamma-carboxyglutamic acid; in particular salts of monocarboxylic acids other than pyrrolidonecarboxylic acid, 100 OE and 500 OE ethoxylated stearic acids and linoleic acid. According to a particular embodiment, the polysaccharide(s) bearing amine group(s) are chosen from a mixture of polysaccharide(s) bearing amine group(s), one of which is a chitosan or an organic or mineral acid salt thereof, preferably the organic acid salts thereof, more particularly chosen from lactic acid, the α or β anomers thereof, the L- or D- configuration optical isomers thereof, and the solvates thereof, such as the hydrates thereof. According to a particular embodiment, the polysaccharide(s) bearing amine group(s) is a single polysaccharide bearing amine group(s), in particular a mixture of chitosan or an organic or mineral acid salt thereof, or more particularly organic acid salts thereof, more particularly chosen from the lactic acid salt thereof, the α or β anomers thereof, the L- or D- configuration optical isomers thereof, and the solvates thereof, such as the hydrates thereof. According to a particular embodiment, the polysaccharide(s) bearing amine group(s) is a single polysaccharide bearing amine group(s), in particular a chitosan or an organic or mineral acid salt thereof, or more particularly the organic acid salts thereof, preferably chosen from the lactic acid salt thereof, the α or β anomers thereof, the L- or D-configuration optical isomers thereof, and the solvates thereof, such as the hydrates thereof. According to one embodiment, the acyclic polymers b) are chosen from nonionic polymers. In particular, the polymers b) may be chosen from alkyl esters or ethers of polyols, such as glycerol. Examples of glycerol esters that may be mentioned include polyglyceryl isostearate, such as the product sold under the name Isolan GI 34^® by the company Evonik. Mention may also be made of polyoxyalkylenated, more particularly polyoxyethylenated and/or polyoxypropylenated, fatty acid esters of glycerol, for instance the stearic acid ester of polyethylene glycol having the INCI name PEG-100 Stearate, polyoxyalkylenated, in particular polyoxyethylenated and/or polyoxypropylenated, fatty acid esters, optionally in combination with a fatty acid ester of glycerol, for instance the PEG-100 Stearate / Glyceryl Stearate mixture. The nonionic acyclic polymers b) may also denote oxyalkylenated, in particular oxyethylenated and/or oxypropylenated, fatty alcohol ethers. According to another embodiment, the nonionic acyclic polymers b) may be chosen from polyesters, in particular from polyhydroxy acids, notably C8-C30 polyhydroxy acids, such as polyhydroxystearic acids. According to one embodiment, the nonionic acyclic polymers b) may be chosen from (co)polymers P having at least one unit of formula (II) and optionally at least one unit of formula (III). [Chem 9] in which formula (II): - q denotes an integer greater than or equal to 2, and - R^a represents a hydrogen atom or a linear or branched (C1-C4)alkyl group; preferably, R^a represents a hydrogen atom; [Chem 10] in which formula (III): - t represents an integer greater than or equal to 2; - R represents a linear or branched, saturated or unsaturated, aromatic or non-aromatic, cyclic or acyclic hydrocarbon-based chain comprising from 1 to 10 carbon atoms; preferably, R represents a (C₁-C₆)alkyl group, in particular methyl; and - R^a represents a hydrogen atom or a linear or branched (C₁-C₄)alkyl group; preferably, R^a represents a hydrogen atom; Preferably, the (co)polymer(s) P are copolymers. According to a preferred embodiment, the (co)polymer(s) P comprise at least one unit of formula (II) and at least one unit of formula (III). According to a preferred embodiment, the (co)polymer(s) P have a mass-average molecular weight ranging from 1000 g/mol to 1000000 g/mol, preferably from 5000 g/mol to 500000 g/mol, and more preferentially from 10000 g/mol to 300000 g/mol. According to a particular embodiment, the (co)polymer(s) P as defined above denote in particular poly(vinyl alcohols) (PVA). In particular, the (co)polymer(s) P may be poly(vinyl alcohols) (PVA) which are partially or totally hydrolyzed, notably those sold under the reference Kuraray Poval by the company Kuraray, notably the POVAL range, or else those sold by the company Sigma-Aldrich (see, for example, https://www. sigmaaldrich.com/FR/en/search/poly(vinyl- alcohol)?focus=products&page=1&perpage=30&sort=relevance&term=poly%28vinyl%20 alcohol%29&type=product). It may in particular be poly(vinyl alcohol) chosen from: - poly(vinyl alcohols) with an average molecular weight Mw of 89000-98000, more than 99% hydrolyzed; - poly(vinyl alcohols) with an average molecular weight M_w of 30000 to 70000, from 87% to 90% hydrolyzed; - poly(vinyl alcohols) with an average molecular weight Mw of 13000-23000, from 87% to 89% hydrolyzed; - poly(vinyl alcohols) with an average molecular weight M_w of 9000-10000, 80% hydrolyzed; - poly(vinyl alcohols) with an average molecular weight M_w of 146000-186000, more than 99% hydrolyzed; - poly(vinyl alcohols) with an average molecular weight Mw of 85000-124000, more than 99% hydrolyzed; - poly(vinyl alcohols) with an average molecular weight M_w of 31000-50000, from 98% to 99% hydrolyzed; - poly(vinyl alcohols) with an average molecular weight Mw of 31000-50000, from 87% to 89% hydrolyzed; - poly(vinyl alcohols) with an average molecular weight M_w of 85000-124000, from 87% to 89% hydrolyzed; - poly(vinyl alcohols) with an average molecular weight M_w of 146000-186000, from 87% to 89% hydrolyzed; - poly(vinyl alcohols) with an average molecular weight Mw of 13000-23000, 98% hydrolyzed; - poly(vinyl alcohols) with an average molecular weight M_w of 130000, more than 99% hydrolyzed; - fully hydrolyzed poly(vinyl alcohol); - poly(vinyl alcohol) sold by the company Sigma-Aldrich under the reference 4-88 Emprove^® Essential; - poly(vinyl alcohol) sold by the company Sigma-Aldrich under the reference 8-88 Emprove^® Essential (CAS No.9002-89-5, M_w equal to 67000); or - poly(vinyl alcohol) sold by the company Sigma-Aldrich under the reference 40-88 Emprove^® Essential. Preferably, the (co)polymer(s) according to the invention may be prepared from partially hydrolyzed poly(vinyl alcohol), more preferentially 88% hydrolyzed. In particular, this may be the poly(vinyl alcohol) sold by the company Sigma-Aldrich under the reference 8-88 Emprove^® Essential. According to a particular embodiment, the polymer(s) b) are chosen from acyclic polymers, preferably from anionic acyclic polymers. By way of example, mention may be made of the polymers b) chosen from amino acids modified with at least one C8-C30, preferably C8-C24, hydrocarbon-based chain, and salts thereof, in particular acyl glutamic acids (INCI name: acyl glutamic acid) or a salt thereof such as acyl glutamates, in particular stearoyl glutamic acid or a salt thereof, more particularly sodium stearoyl glutamate (INCI name). Such compounds are sold under the name Amisoft by the company Ajinomoto and notably under the references Amisoft CA, Amisoft LA, Amisoft HS 11 PF, Amisoft MK-11, Amisoft LK-11, Amisoft CK-11, or else under the name Eumulgin SG by the company Cognis. According to a particular embodiment, the polymer(s) b) are chosen from polyamino and hydrocarbon-based acyclic polymers. Such polymers do not comprise any silicon atoms. In particular, the polyamino polymers may be chosen from diamino polymers, and more particularly from polyether diamines in particular of formula H2N-ALK-O-[ALK’-O]m- ALK’’-NH₂ with ALK, ALK’ and ALK’’, which may be identical or different, representing a linear or branched (C₁-C₆)alkylene group, and m representing an integer greater than or equal to 0, such as 4,7,10-trioxa-1,13-tridecanediamine or the compounds known under the reference Jeffamine from the company Huntsman, and more particularly α,ω-diamino polyethylene glycol and/or polypropylene glycol (with an amine function at the end of the chain), for example the products sold under the names Jeffamine D-230, D-400, D-2000, D- 4000, ED-600, ED-9000 and ED-2003. In particular, the polyamino polymer(s) may be chosen from triamino polymers, i.e. containing three primary and/or secondary amine groups, preferably primary (NH2). More particularly, they are chosen from polyether triamines notably of formula ALK’’’[(O- ALK’)m-NH₂]₃ with ALK’ as defined previously and ALK’’’ representing a linear or branched trivalent (C₁-C₆)alkylene group, and m representing an integer greater than or equal to 0. As (poly)amino compounds that are triamino compounds, mention may be made in particular of polyether triamines, and notably α,ω-diamino polyethylene glycol and/or polypropylene glycol (with an amine function at the end of the chain), for example the products sold under the name Jeffamine T-403. According to a particular embodiment, the (poly)amino compound(s) include more than three primary and/or secondary amine groups, preferably primary (NH₂). In particular, the (poly)amino compound(s) are chosen from poly(meth)acrylates or poly(meth)acrylamides bearing lateral primary or secondary amine functions, more particularly chosen from poly(3-aminopropyl)methacrylamide and poly(2-aminoethyl) methacrylate. According to a particular embodiment, the polyamino compound(s) are chosen from: - poly((C2-C5)alkyleneimines), and preferably from polyethyleneimines and polypropyleneimines, notably poly(ethyleneimines), in particular those sold under the reference 408700 by the company Aldrich Chemical or under the reference 408727 by the company Aldrich Chemical (example MW = 25000) or under the trade name Lupasol by BASF, notably with a molecular weight of between 1200 and 30000, - poly(allylamine), in particular the product sold under reference 479136 by the company Aldrich Chemical, - polyvinylamines and copolymers thereof, notably with vinylamides, in particular vinylamine/vinylformamide copolymers, - polyamino acids containing NH2 groups, such as polylysine, in particular the product sold by the company JNC Corporation (formerly Chisso), - amino dextran, in particular the product sold by the company CarboMer Inc, - amino polyvinyl alcohol, in particular the product sold by the company CarboMer Inc, - acrylamido(C1-C6)alkylamine-based copolymers, notably based on acrylamidopropylamine, and - mixtures thereof. As amino polymer, mention may also be made of α,ω-diamino polytetrahydrofurans (or polytetramethylene glycol) and α,ω-diamino polybutadienes. According to a particular embodiment, the (poly)amino compounds are chosen from hyperbranched polymers comprising at least one amino group and dendrimers bearing at least one amino group, in particular polyamidoamine PAMAM dendrimers with an ethylenediamine core and a terminal amine function. According to a particular embodiment, the polymer(s) b) are chosen from polyamino acids and preferably from proteins. Preferably, the proteins are of plant origin. As examples of polymers b) chosen from plant proteins, mention may be made of soy proteins. The acyclic polymer(s) b) may be anionic, cationic or nonionic, preferably anionic, more preferentially anionic, particularly bearing carboxyl, carboxylate, sulfate, sulfonic acid, sulfonate, phosphate, phosphonic acid or phosphonate groups, preferably chosen from carboxylates and carboxylic acids. According to a particular embodiment, the acyclic polymers b) are anionic, in particular bearing carboxyl groups or carboxylates of alkali metals or alkaline-earth metals such as sodium, and are chosen from homo- or copolymers of (meth)acrylic acid. The (meth)acrylic acid copolymers are in particular copolymers of (meth)acrylic acid with alkyl (poly)ether (meth)acrylates, in particular copolymers of (meth)acrylic acid and POE/POP (meth)acrylate, for example polyether polycarbonate, sodium salt in aqueous solution, for example sold under the name RSY 15007 Cosmetic Version by the company Arkema-Coatex. According to a preferred embodiment, the polymer(s) b) are chosen from: - lignosulfonic acid, lignosulfonates, sulfonic polystyrenes, polystyrene sulfonates, anionic polyanethole derivatives, in particular polyanethole sulfonates, and mixtures thereof, - alkyl esters or ethers of polyols, in particular of glycerol, - anionic polysaccharides, preferably chosen from sulfated polysaccharides, in particular ulvans, dextran sulfates, carrageenans and mixtures thereof, and polysaccharide carboxylates, in particular alginates, - cationic polysaccharides, preferably chosen from polysaccharides bearing amine groups, in particular chitosans, - modified polysaccharides, in particular chosen from polysaccharide esters, and preferably from pullulan esters, - poly((C₂-C₅)alkyleneimines), and preferably from polyethylenimines and polypropyleneimines, notably poly(ethyleneimines), - polyamino acids, and preferably from proteins, - anionic acyclic polymers bearing carboxyl groups or carboxylates of alkali metals or alkaline-earth metals, such as sodium, and chosen from homo- or copolymers of (meth)acrylic acid, preferably from sodium polymethacrylates and copolymers of (meth)acrylic acid with alkyl (poly)ether (meth)acrylates, in particular copolymers of (meth)acrylic acid and POE/POP (meth)acrylate, and - mixtures thereof. According to a more preferred embodiment, the polymer(s) b) are chosen from: - lignosulfonates, notably of alkali metals or alkaline-earth metals, such as sodium or calcium lignosulfonates, - carrageenans, - chitosans, - alginates, notably of alkali metals or alkaline-earth metals, such as sodium alginate, - dextrans, in particular of alkali metals or alkaline-earth metals, and dextran sulfates of alkali metals or alkaline-earth metals, such as sodium dextran sulfate, - polyhydroxystearic acids, - starches and derivatives thereof, notably phosphated derivatives thereof, such as hydroxypropyl corn distarch phosphate, - pullulans and ester derivatives thereof, notably of C1-C30, preferably C10-C20 carboxylic acid, such as myristoyl pullulan, - polyvinyl alcohols, - optionally hydrolyzed proteins, such as optionally hydrolyzed soy proteins, and - mixtures thereof. According to an even more preferred embodiment, the polymer(s) b) are chosen from: - lignosulfonates, - carrageenans, - chitosans, - alginates, such as sodium alginate, - dextrans, such as sodium dextran sulfate, - polyhydroxystearic acids, - starches and derivatives thereof, such as hydroxypropyl corn distarch phosphate, - pullulans and ester derivatives thereof, such as myristoyl pullulan, - polyvinyl alcohols, - proteins, such as optionally hydrolyzed soy proteins, and - mixtures thereof. Inorganic compound c) According to a particular embodiment, the composite materials according to the invention may also comprise at least one inorganic compound c) different from said bismuth oxycarbonate particles a). The inorganic compound(s) c) may be amorphous or crystalline, hydrated or non-hydrated forms of oxides or hydroxides or oxy-hydroxides of alkali metals or alkaline-earth metals, notably sodium, potassium, magnesium and calcium, or transition metals, notably titanium, aluminum, manganese, iron, copper, niobium and tantalum, or lanthanides, notably cerium, or poor metals, notably zinc, indium and bismuth. The inorganic oxides may also denote amorphous or crystalline, hydrated or non-hydrated forms of metalloid oxides or hydroxides or oxy-hydroxides. In particular, the inorganic compounds c) may be amorphous or crystalline, hydrated or non- hydrated forms, including clays, of silicon oxides or hydroxides or oxy-hydroxides such as silica SiO2, lithium and/or sodium and/or potassium and/or ammonium and/or calcium and/or magnesium and/or aluminum and/or titanium and/or iron and/or zinc and/or bismuth silicates, aluminum and/or calcium and/or magnesium and/or sodium and/or titanium and/or iron and/or zinc and/or bismuth borosilicates. In particular, the inorganic compounds c) may be amorphous or crystalline, hydrated or non- hydrated forms of inorganic carbides or sulfides or nitrides, such as silicon carbides, iron, copper and zinc sulfides or such as boron and silicon nitrides. As metal oxides, mention may be made of the hydrated or non-hydrated forms of Al2O3, Al(OH)₃, SiO₂, TiO₂, MnO, MnO₂, FeO(OH), Fe₃O₄, Fe₂O₃, Cu(OH)₂, Cu₂O, CuO, Zn(OH)2, ZnO, Nb2O5, In(OH)3, In2O3, Ce2O3, CeO2, Ta2O5, WO3, Bi2O3, and mixtures thereof. Preferably, use will be made of hydrated or non-hydrated forms of Al₂O₃ such as Al(OH)₃, hydrated or non-hydrated forms of SiO₂, TiO₂, ZnO, and mixtures thereof, more preferentially hydrated or non-hydrated forms of Al2O3 such as Al(OH)3, or the hydrated or non-hydrated forms of SiO2, TiO2, ZnO and mixtures thereof, and even more preferentially the hydrated or non-hydrated forms of Al₂O₃ such as Al(OH)₃, or SiO₂, and mixtures thereof. According to a preferred embodiment, the composite materials according to the invention do not comprise any inorganic compound c) different from said bismuth oxycarbonate particles a). According to another preferred embodiment, the composite materials according to the invention comprise only one inorganic compound c) different from said bismuth oxycarbonate particles a), preferably chosen from inorganic oxides, and more preferentially from silica, alumina, titanium dioxide and zinc oxide, and better still from silica. According to another preferred embodiment, the composite materials according to the invention comprise only one inorganic compound c) different from said bismuth oxycarbonate particles a), preferably chosen from inorganic hydroxides or inorganic oxy- hydroxides, more preferentially from inorganic hydroxides, more preferentially from Al(OH)3, Zn(OH)2, In(OH)3 or mixtures thereof, even more preferentially from Al(OH)3, Zn(OH)2, and better still Al(OH)3. Preferably, the composite material according to the invention comprises one or more inorganic compounds c) different from said bismuth oxycarbonate particles a), preferably chosen from inorganic oxides, and more preferentially from zinc, titanium, silicon and/or aluminum oxides, preferably from silicon and/or aluminum oxides, which are optionally hydrated. Preferably, the composite material according to the invention comprises one or more inorganic compounds c) different from said bismuth oxycarbonate particles a), preferably chosen from an inorganic oxide, more preferentially chosen from Al(OH)₃, SiO₂, TiO₂ and ZnO, and even more preferentially chosen from Al(OH)3 or SiO2. PROCESS FOR PREPARING THE COMPOSITE MATERIAL The composite materials according to the invention may notably be obtained via the preparation processes described below. In particular, the composite materials according to the invention as defined previously may be obtained in one or more steps. The composite materials may in particular be obtained conventionally via various processes, notably bringing the bismuth oxycarbonate particles a) into contact with a solution comprising at least one polymer b) in a solvent or a mixture of solvents A. In particular, the process for preparing the composite materials according to the invention uses: - particles of bismuth oxycarbonate a) of formula (I) (BiO)2-x(CO3), formula (I), and solvates thereof, such as hydrates thereof, in which -0.4 < x < 0.6, the largest mean dimension of said particles being less than 400 nm; - optionally one or more precursors intended to form the inorganic compound(s) c) different from said bismuth oxycarbonate particles; - one or more polymers b) as defined previously; - optionally one or more additives; and - optionally one or more solvents. According to a particular embodiment, the process for preparing the composite materials according to the invention may comprise one or more separation steps. In particular, the precursor(s) intended to form the inorganic compound(s) c) different from said bismuth oxycarbonate particles a) are chosen from organic or inorganic compounds which make it possible to obtain particles of bismuth oxycarbonate a) and of inorganic compound c) by chemical reaction or physical adsorption. In particular, said precursor(s) may be chosen from: - the inorganic compounds c) as described previously, - inorganic metal precursors of chemical elements and hydrates thereof, in particular dissolved metal oxides, notably sodium silicates or aluminates, halides and hydrates thereof, nitrates and hydrates thereof, carbonates and hydrates thereof, sulfonates and hydrates thereof, sulfates and hydrates thereof, phosphates and hydrates thereof, - organic metal precursors and hydrates thereof, in particular alkoxides and hydrates thereof, carboxylates and hydrates thereof, lactates and hydrates thereof, or citrates and hydrates thereof, and - mixtures thereof. Said precursor(s) intended to form the ancillary inorganic compound(s) c) may also be chosen from oxidizing precursors, in particular air, hydrogen peroxide, peroxides and hydrates thereof, and/or sulfiding agents, in particular hydrogen sulfide, alkali metal sulfides and hydrates thereof, and/or nitriding agents. According to a preferred embodiment, the process for preparing the composite materials according to the invention does not use precursors intended to form the inorganic compound(s) c) different from said bismuth oxycarbonate particles a). According to a preferred embodiment, the process for preparing the composite materials according to the invention uses at least one precursor intended to form the inorganic compound(s) c) different from said bismuth oxycarbonate particles a), and preferably chosen from sodium silicate and sodium aluminate. According to a particular embodiment, the process for preparing the composite materials according to the invention uses at least one solvent. The choice of solvent(s) may in particular depend on the precursor(s) and additives used in the process. In particular, the solvent(s) may be chosen from polar or apolar, protic or aprotic solvents. According to a particular embodiment, the process for preparing the composite materials according to the invention uses at least one additive. In particular, the additive(s) may be chosen from acids, in particular mineral acids such as hydrochloric acid or sulfuric acid, and bases, preferably mineral bases such as sodium hydroxide or potassium hydroxide. According to a particular embodiment, the present invention is directed towards a process for preparing the composite materials as defined previously, comprising at least the steps of: (i) providing at least one particle of bismuth oxycarbonate a) of formula (I) (BiO)2-x(CO3), formula (I), and solvates thereof, such as hydrates thereof, in which -0.4 < x < 0.6, the largest mean dimension of said particles being less than 400 nm, optionally dispersed in at least one solvent or mixture of solvents A; (ii) providing a solution of at least one polymer b), optionally in a solvent or mixture of solvents B; (iii) bringing said at least one particle a) or dispersion (i) and said solution (ii) in contact to form the composite material; (iv) isolating said composite material. Preferably, step (i) does not use a solvent A. According to one embodiment, the solvent(s) of steps (i) and (ii) may be identical or different. In particular, the solvent(s) A and/or B are chosen from apolar aprotic solvents, polar protic solvents, more preferentially from water, alcohols, polyols and mixtures thereof. In particular, when the polymer(s) b) are hydrophilic and/or amphiphilic, the solvent or mixture of solvents B is polar, and when the polymer(s) are hydrophobic and/or amphiphilic, the solvent or mixture of solvents B is apolar. In particular, when the polymer(s) b) are hydrophilic and/or amphiphilic, the solvent or mixture of solvents B is polar and protic, and preferably chosen from water, polyols and/or mixtures thereof, and more preferentially is water. In particular, when the polymer(s) b) are hydrophobic and/or amphiphilic, the solvent or mixture of solvents B is apolar, and preferably chosen from volatile and non-volatile oils or organic solvents. Preferably, the mixture (iii) is kept stirring at atmospheric pressure for a duration ranging from 5 minutes to 24 h, in particular at a temperature ranging from 20 °C to 200 °C, and notably in the open air or under an inert atmosphere. According to a particular embodiment, the process for preparing the composite materials according to the invention may comprise one or more separation steps, in particular by centrifugation and/or by filtration, in particular ultrafiltration, and/or by lyophilization and/or by atomization. According to a particular embodiment, the process for preparing the composite materials also comprises a centrifugation step. In particular, according to this embodiment, the process for preparing the composite materials also comprises: - optionally, a step of adding a solvent or mixture of solvents S in which the polymer(s) b) is not or are not soluble, i.e. the polymer b) precipitates out from the solvent or mixture of solvents S at a temperature ranging from 0 °C to room temperature, to precipitate the composite materials; - at least one centrifugation step, preferably at between 4000 rpm and 14000 rpm, in particular for a duration ranging from 1 min to 1 h; and - optionally at least one washing step, preferably with the solvent or mixture of solvents S; - optionally at least one drying step, in particular in an oven, preferably at a temperature of 50 °C and notably under vacuum (pressure equal to 10 mmHg), to isolate the composite materials. According to a particular embodiment, the process for preparing the composite materials also comprises a filtration step, in particular an ultrafiltration step. In particular, according to this embodiment, the process for preparing the composite materials also comprises: - optionally a step of adding a solvent or mixture of solvents S, - a step of separating the composite materials from the mixture of solvents by filtration, in particular by ultrafiltration, on a membrane preferably having a pore size ranging from 1 nm to 1 µm, better still from 1 to 100 nm, - optionally at least one centrifugation step; - optionally at least one washing step; and - optionally at least one drying step, in particular in an oven, preferably at a temperature of 50 °C and notably under vacuum (pressure equal to 10 mmHg), to isolate the composite materials. According to a particular embodiment, the process for preparing the composite materials also comprises a lyophilization step. In particular, according to this embodiment, the process for preparing the composite materials also comprises a step of lyophilization of the mixture, in particular at a temperature ranging from 0 °C to -180 °C, optionally after evaporation of one or more solvents when the reaction medium comprises a plurality of solvents. According to a particular embodiment, the process for preparing the composite materials also comprises an atomization step. In particular, according to this embodiment, the process for preparing the composite materials also comprises a step of atomization of the mixture. In particular, the atomization temperature is preferably less than or equal to the lowest characteristic transition temperature of the polymer b) or of all the polymers b) constituting the mixture, “transition” referring to a potential glass transition and/or a potential melting and/or a potential degradation, and is greater than the lowest boiling point of the solvent or solvents of the mixture. Preferably, the atomization temperature ranges from 80 °C to 250 °C, more preferentially from 100 °C to 200 °C, and even more preferentially from 100 °C to 180 °C. COSMETIC COMPOSITION The composite materials according to the invention may in particular be used in a composition, notably in a cosmetic composition. Thus, the present invention also relates to a composition, notably a cosmetic composition, comprising at least one composite material as defined previously. According to a preferred embodiment, the present invention also relates to a composition, notably a cosmetic composition, comprising at least: i) at least one composite material as defined previously; ii) at least one aqueous phase and/or at least one fatty phase; and iii) at least one compound chosen from: 1) UV-screening agents different from the composite materials i); 2) colorants; 3) cosmetic active agents for caring for keratin materials; 4) surfactants; 5) thickeners; and mixtures thereof. Said composite materials may be present in the composition, preferably cosmetic composition, in a content ranging from 0.5% to 70% by weight, preferably from 1% to 50% by weight, better still from 2% to 40% by weight relative to the total weight of the composition. Aqueous phase A composition, notably a cosmetic composition, according to the invention may comprise at least one aqueous phase. The aqueous phase may comprise water and optionally a water-soluble solvent. In the present invention, the term “water-soluble solvent” denotes a compound that is liquid at room temperature and water-miscible (miscibility in water of greater than 50% by weight at 25 °C and atmospheric pressure). The water-soluble solvents that may be used in a composition according to the invention may also be volatile. Among the water-soluble solvents that may be used in a composition in accordance with the invention, mention may be made notably of lower monoalcohols containing from 1 to 5 carbon atoms, such as ethanol and isopropanol, C₂-C₃₂ polyols, C₃ and C₄ ketones and C₂- C4 aldehydes. Among the water-soluble solvents that may be used in a composition in accordance with the invention, mention may notably be made of polyols. For the purposes of the present invention, the term “polyol” means any organic molecule including at least two free hydroxyl groups. A polyol that is suitable for use in the invention may be a compound of linear, branched or cyclic, saturated or unsaturated alkyl type, bearing on the alkyl chain at least two –OH functions and in particular at least three –OH functions. The polyols that are advantageously suitable for formulating a composition according to the present invention are those notably containing from 2 to 32 carbon atoms and preferably 3 to 16 carbon atoms. Advantageously, the polyol may be chosen, for example, from pentaerythritol, trimethylolpropane, caprylyl glycol, glycerol, polyglycerols, such as glycerol oligomers, for instance diglycerol, polyethylene glycols, polypropylene glycols, and mixtures thereof. Fatty phase A composition, notably a cosmetic composition, according to the invention may also comprise at least one fatty phase, in particular an oily phase. For the purposes of the invention, the term "fatty phase" means a phase comprising at least one fatty substance and all the liposoluble and lipophilic ingredients used for formulating the compositions of the invention. Preferably, the fatty phase comprises at least one oil, notably a cosmetic oil. The term “oil” means a water-immiscible non-aqueous compound that is liquid at room temperature (25 °C) and at atmospheric pressure (760 mmHg). The fatty phase may comprise at least one volatile or non-volatile hydrocarbon-based oil and/or a fatty substance. As non-volatile hydrocarbon-based oils, mention may notably be made of hydrocarbon- based oils of plant origin, synthetic ethers containing from 10 to 40 carbon atoms, linear or branched hydrocarbons of mineral or synthetic origin, synthetic esters, fatty alcohols that are liquid at room temperature and bearing a branched and/or unsaturated carbon chain containing from 12 to 26 carbon atoms, C₁₂-C₂₂ higher fatty acids, carbonates, and mixtures thereof. As volatile hydrocarbon-based oils, mention may notably be made of hydrocarbon-based oils containing from 8 to 16 carbon atoms. The non-volatile silicone oils may notably be chosen from non-volatile polydimethylsiloxanes (PDMSs) and phenyl silicones. As volatile silicone oils, mention may be made, for example, of volatile linear or cyclic silicone oils. Use may also be made of volatile fluoro oils, such as nonafluoromethoxybutane, decafluoropentane, tetradecafluorohexane, dodecafluoropentane, and mixtures thereof. The oily phase may also comprise other fatty substances, mixed with or dissolved in the oil. Another fatty substance that may be present in the oily phase may be, for example, a fatty acid, a wax, a gum, a pasty compound, or mixtures thereof. 1) Additional UV-screening agents According to a particular embodiment, a composition according to the invention comprises 1) at least one additional UV-screening agent different from the composite materials required according to the invention and defined above. For the purposes of the present invention, the term “UV-screening agent different from the composite materials” is intended to denote any UV-screening agent, the chemical nature of which differs from that of the composite materials required according to the invention and defined above. The composite materials according to the invention may thus be used alone or in combination with 1) other UV-screening agents, in particular chosen from organic and/or inorganic UV-screening agents. Thus, the cosmetic composition may also contain one or more additional UV-screening agents chosen from hydrophilic, lipophilic or insoluble organic UV-screening agents and/or mineral UV-screening agents different from the composite materials according to the invention. The term “hydrophilic UV-screening agent” means any cosmetic or dermatological organic or inorganic compound for filtering UV radiation, which may be fully dissolved in molecular form in a liquid aqueous phase or else which may be in a colloidal suspension (for example in micellar form) in a liquid aqueous phase. The term “lipophilic UV-screening agent” means any cosmetic or dermatological organic or inorganic compound for filtering UV radiation, which may be fully dissolved in molecular form in a liquid fatty phase or else which may be in a colloidal suspension (for example in micellar form) in a liquid fatty phase. The term “insoluble UV-screening agent” means any cosmetic or dermatological organic or inorganic compound for filtering UV radiation which has a solubility in water of less than 0.5% by weight and a solubility of less than 0.5% by weight in the majority of organic solvents such as liquid paraffin, fatty alcohol benzoates and fatty acid triglycerides, for example Miglyol 812^®. This solubility, determined at 70 °C, is defined as the amount of product in solution in the solvent at equilibrium with an excess of solid in suspension after returning to room temperature. It may be readily evaluated in the laboratory. The additional organic UV-screening agents are notably chosen from: - cinnamic compounds, in particular Ethylhexyl Methoxycinnamate, - anthranilate compounds, in particular Menthyl anthranilate, - salicylic compounds, in particular Homosalate and Ethylhexyl Salicylate, - dibenzoylmethane compounds, in particular Butyl Methoxydibenzoylmethane, - benzylidenecamphor compounds, in particular 3-Benzylidene camphor, 4- Methylbenzylidene camphor, Benzylidene Camphor Sulfonic Acid and Terephthalylidene Dicamphor Sulfonic Acid, - benzophenone compounds, in particular oxybenzone and n-hexyl 2-(4-diethylamino-2- hydroxybenzoyl)benzoate, - β,β-diphenylacrylate compounds, in particular octocrylene, - triazine compounds, in particular Phenylene Bis-Diphenyl triazine, Bis- Ethylhexyloxyphenol Methoxyphenyl Triazine, Ethylhexyl Triazone and Diethylhexyl Butamido Triazone, - benzotriazole compounds, in particular Drometrizole Trisiloxane, - benzalmalonate compounds, notably those mentioned in patent US 5624663, in particular Polysilicone-15, - benzimidazole derivatives, in particular Phenylbenzimidazole Sulfonic Acid, - imidazoline compounds, in particular Ethylhexyl Dimethoxybenzylidene Dioxoimidazoline Propionate, - bis-benzazolyl compounds, such as those described in patents EP 0669323 and US 2463264, in particular Disodium Phenyl Dibenzimidazole Tetra-sulfonate, - para-aminobenzoic compounds, in particular PABA, Ethylhexyl Dimethyl PABA and PEG-25 PABA, - methylenebis(hydroxyphenylbenzotriazole) compounds, such as those described in patent applications US 5237071, US 5166355, GB 2303549, DE 19726184 and EP 0893119, in particular Methylenebis-Benzotriazolyl Tetramethylbutylphenol, - benzoxazole compounds, such as those described in patent applications EP 0832642, EP 1027883, EP 1300137 and DE 10162844, in particular 2,4-bis-[5- 1(dimethylpropyl)benzoxazol-2-yl-(4-phenyl)imino]-6-(2-ethylhexyl)imino-1,3,5-triazine, - polymeric screening agents and silicone screening agents, such as those notably described in patent application WO 93/04665, - ^-alkylstyrene-derived dimers, such as those described in patent application DE 19855649, - 4,4-diarylbutadiene compounds, such as those described in patent applications EP 0967200, DE 19746654, DE 19755649, EP 1008586, EP 1133980 and EP 0133981, in particular 1,1-dicarboxy(2,2’-dimethylpropyl)-4,4-diphenylbutadiene, and - mixtures thereof. The additional inorganic UV-screening agents are generally mineral UV-screening agents, in particular chosen from metal oxides. The metal oxides may notably be chosen from titanium oxide, zinc oxide, iron oxide, zirconium oxide and cerium oxide, and mixtures thereof. The metal oxide particles may be coated or uncoated. The coated particles are more particularly titanium oxide particles coated with silica, with silica and iron oxide, with silica and alumina, with alumina, with alumina and aluminum stearate, with silica, alumina and alginic acid, with alumina and aluminum laurate, with iron oxide and iron stearate, with zinc oxide and zinc stearate, with silica and alumina and treated with a silicone, with silica, alumina and aluminum stearate and treated with a silicone, with silica and treated with a silicone, with alumina and treated with a silicone, with triethanolamine, with stearic acid, with sodium hexametaphosphate, or else TiO₂ treated with octyltrimethylsilane, TiO₂ treated with a polydiemethylsiloxane, anatase/rutile TiO₂ treated with a polydimethylhydrogenosiloxane, TiO2 coated with triethylhexanoin, with aluminum stearate and with alumina, TiO2 coated with aluminum stearate, with alumina and with silicone, TiO₂ coated with lauroyl lysine, or TiO₂ coated with C_9-15 fluoro alcohol phosphate and aluminum hydroxide. The metal oxides may optionally be doped. In this regard, mention may be made of TiO₂ particles doped with at least one transition metal, such as iron, zinc or manganese and more particularly manganese. The doped particles may be in the form of a dispersion, preferably an oily dispersion. The oil present in the oily dispersion is preferably chosen from triglycerides including those of capric/caprylic acids. The oily dispersion of titanium oxide particles may additionally comprise one or more dispersants, for example a sorbitan ester or a polyoxyalkylenated glycerol fatty acid ester. Mention may be made more particularly of the oily dispersion of TiO₂ particles doped with manganese in capric/caprylic acid triglyceride in the presence of tri-PPG-3 myristyl ether citrate and polyglyceryl-3 polyricinoleate and sorbitan isostearate. Mention may also be made of mixtures of metal oxides, notably of titanium dioxide and of cerium dioxide, including the equal-weight mixture of titanium dioxide and cerium dioxide coated with silica, and the mixture of titanium dioxide and zinc dioxide coated with alumina, silica and silicone, or coated with alumina, silica and glycerol. 2) Colorants According to a particular embodiment, a composition according to the invention comprises 2) at least one colorant. In general, the term “colorant” is understood to denote any compound that is capable of coloring a composition, that is to say which absorbs in the visible spectrum, in particular so as to appear to the human eye to have a color such as yellow, orange, red, purple, blue or green. Preferably, a composition according to the invention comprises at least one pigment. The term “pigments” should be understood as meaning white or colored, mineral or organic particles that are insoluble in liquid lipophilic and hydrophilic phases, and which are intended to color and/or opacify the composition containing them, and which are different from the composite materials according to the invention. More particularly, the pigments have little or no solubility in aqueous-alcoholic media. The pigments that may be used are notably chosen from the organic and/or mineral pigments known in the art, notably those described in Kirk-Othmer’s Encyclopedia of Chemical Technology and in Ullmann’s Encyclopedia of Industrial Chemistry (Ullmann's Encyclopedia of Industrial Chemistry “Pigment organics”, 2005 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim 10.1002/14356007.a20 371 and ibid, “Pigments, Inorganic, 1. General” 2009 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim10.1002/14356007.a20_243.pub3). These pigments may be in pigment powder or paste form. They may be coated or uncoated. The pigments may be chosen, for example, from mineral pigments, organic pigments, lakes, pigments with special effects such as nacres or glitter flakes, and mixtures thereof. The pigment may be a mineral pigment. The term “mineral pigment” refers to any pigment that satisfies the definition in Ullmann’s encyclopedia in the chapter on inorganic pigments. Among the mineral pigments that are useful in the present invention, mention may be made of iron oxides, chromium oxides, manganese violet, ultramarine blue, chromium hydrate, ferric blue and titanium oxide. The pigment may be an organic pigment. The term “organic pigment” refers to any pigment that satisfies the definition in Ullmann’s encyclopedia in the chapter on organic pigments. The organic pigment may notably be chosen from nitroso, nitro, azo, xanthene, quinoline, anthraquinone, phthalocyanine, metal-complex type, isoindolinone, isoindoline, quinacridone, perinone, perylene, diketopyrrolopyrrole, thioindigo, dioxazine, triphenylmethane or quinophthalone compounds. Preferably, the pigment(s) that are suitable for use in the invention are chosen from carbon black, iron oxides, notably red, brown or black iron oxides, and micas coated with iron oxide, triarylmethane pigments, notably blue and purple triarylmethane pigments, such as Blue 1 Lake, azo pigments, notably red azo pigments, such as D&C Red 7, alkali metal salts of lithol red, such as the calcium salt of lithol red B; more preferentially, the pigment(s) used are chosen from red iron oxides and azo pigments, notably red azo pigments such as D&C Red 7. The colorant(s) may be present in a composition according to the invention in a content ranging from 0.001% to 10% by weight and preferably from 0.005% to 5% by weight relative to the total weight of the composition. According to a particular embodiment of the invention, the amount of pigments ranges from 0.5% to 40% and preferably from 1% to 20% relative to the weight of the composition of the invention comprising them. 3) Cosmetic active agent According to a particular embodiment, a composition according to the invention comprises 3) at least one cosmetic active agent for caring for keratin materials, preferably for caring for the skin. In particular, the cosmetic active agent may be at least one hydrophilic active agent and/or one lipophilic active agent which is preferably hydrophilic. The term “hydrophilic active agent” means a water-soluble or water-dispersible active agent which is capable of forming hydrogen bonds. As cosmetic active agents 3), mention may for example be made of moisturizers, depigmenting agents, desquamating agents, humectants, anti-ageing agents, mattifying agents, cicatrizing agents, antibacterial agents, vitamins and derivatives or precursors thereof, antioxidants, free-radical scavengers; anti-pollutants; self-tanning agents; anti- glycation agents; calmatives; deodorant agents; essential oils; NO-synthase inhibitors; agents for stimulating the synthesis of dermal or epidermal macromolecules and/or for preventing degradation thereof; agents for stimulating fibroblast proliferation; agents for stimulating keratinocyte proliferation; muscle relaxants; refreshing agents; tensioning agents; propigmenting agents; keratolytic agents; slimming agents; agents which act on cell energy metabolism; insect repellents; substance P antagonists or CRGP antagonists; agents for preventing hair loss; and mixtures thereof. The active agent(s) may notably be chosen from: - vitamins and derivatives thereof, notably esters thereof, such as niacinamide (3- pyridinecarboxamide), nicotinamide (vitamin B3), tocopherol (vitamin E) and esters thereof (for instance tocopheryl acetate), ascorbic acid and derivatives thereof (vitamin C), retinol (vitamin A), - humectants or moisturizers such as urea, hydroxyureas, glycerol, polyglycerols, glyceryl glucoside, diglyceryl glucoside, polyglyceryl glucosides, xylityl glucoside and plant extracts (notably of tea, mint, orchid, soy, aloe vera), honey, and in particular glycerol; - C-glycoside compounds, and preferably hydroxypropyl tetrahydropyrantriol (INCI name) (or proxylane); - antioxidant compounds; - anti-ageing active agents, such as hyaluronic acid compounds, and notably sodium hyaluronate, salicylic acid compounds and in particular 5-n-octanoylsalicylic acid (capryloylsalicylic acid), adenosine, and the sodium salt of (3-hydroxy-2- pentylcyclopentyl)acetic acid; - keratolytic agents such as lactic acid or glycolic acid; and - mixtures thereof. Such active agents may be present in a composition according to the invention in a content ranging from 0.05% to 10% by weight and preferably from 1.0% to 8.0% by weight relative to the total weight of the composition. 4) Surfactant According to a particular embodiment, a composition according to the invention comprises 4) at least one surfactant. The surfactants may be chosen from nonionic, anionic, cationic and amphoteric surfactants, and mixtures thereof. Reference may be made to Kirk-Othmer's Encyclopedia of Chemical Technology, Volume 22, pages 333-432, 3rd Edition, 1979, Wiley, for the definition of the emulsifying properties and functions of surfactants, in particular pages 347-377 of this reference, for anionic, amphoteric and nonionic surfactants. Examples of amphoteric surfactants that are suitable for use in the invention are notably chosen form betaines, preferably chosen from alkyl betaines, in particular lauryl betaine, N- alkylamido betaines and derivatives thereof, in particular cocamidopropyl betaine, lauramidopropyl betaine and N-disodium N-carboxyethoxyethyl N-cocoylamidoethyl aminoacetate; sultaines, in particular cocoyl amidopropylhydroxy sultaine; and mixtures thereof. The nonionic surfactants may notably be chosen from alkyl and polyalkyl esters of poly(ethylene oxide), oxyalkylenated alcohols, alkyl and polyalkyl ethers of poly(ethylene oxide), optionally polyoxyethylenated alkyl and polyalkyl esters of sorbitan, optionally polyoxyethylenated alkyl and polyalkyl ethers of sorbitan, in particular alkyl and polyalkyl esters of sucrose, optionally polyoxyethylenated alkyl and polyalkyl esters of glycerol, and optionally polyoxyethylenated alkyl and polyalkyl ethers of glycerol, gemini surfactants, cetyl alcohol, stearyl alcohol, and mixtures thereof. The anionic surfactants may be chosen from alkyl ether sulfates, carboxylates, amino acid derivatives, sulfonates, isethionates, taurates, sulfosuccinates, alkylsulfoacetates, phosphates and alkyl phosphates, polypeptides, metal salts of C₁₀-C₃₀ and notably C₁₆-C₂₅ fatty acids, in particular metal stearates and behenates, and mixtures thereof. The cationic surfactants may be chosen from alkylimidazolidiniums, such as isostearyl ethylimidonium ethosulfate, ammonium salts such as (C_12-30-alkyl)tri(C_1-4-alkyl)ammonium halides such as N,N,N-trimethyl-1-docosanaminium chloride (or behentrimonium chloride). The silicone surfactants may be chosen from dimethicone copolyols or silicone elastomers. A composition according to the invention may comprise between 0.01% and 2.0% by weight of surfactant, preferably between 0.05% and 1.5% by weight, more preferentially between 0.1% and 1.0% by weight, relative to the total weight of the composition. 5) Thickener According to a particular embodiment, a composition according to the invention comprises 5) at least one thickener, also sometimes referred to as gelling agent or viscosity modifier. The thickeners may be synthetic, natural or of natural origin, preferably natural or of natural origin. Such thickeners may more particularly be chosen from natural polymers or polymers of natural origin, in particular of plant origin. These thickeners are preferably hydrophilic, i.e. soluble or dispersible in water. Advantageously, the thickener(s) are chosen from modified or native polysaccharides, in particular modified or unmodified starches, fructans, gellans, glucans, amylose, amylopectin, glycogen, pullulan, dextrans, celluloses and derivatives thereof, in particular methylcelluloses, hydroxyalkylcelluloses, ethylhydroxyethylcelluloses and carboxymethylcelluloses, mannans, xylans, lignins, arabans, galactans, galacturonans, alginate-based compounds, chitin, chitosans, glucuronoxylans, arabinoxylans, xyloglucans, glucomannans, pectic acids and pectins, arabinogalactans, carrageenans, agars, glycosaminoglucans, gum Arabic, sclerotium gum, gum tragacanth, ghatti gums, karaya gums, locust bean gums, konjac gums, galactomannans such as guar gums and nonionic derivatives thereof, in particular hydroxypropyl guar, and ionic derivatives thereof, biopolysaccharide gums of microbial origin, in particular scleroglucan or xanthan gums, mucopolysaccharides, carboxyvinyl polymers, polyacrylamides, polymers and copolymers of 2-acrylamido 2-methylpropane sulfonic acid, optionally crosslinked and/or neutralized, water-soluble or water-dispersible silicone derivatives, such as acrylic silicones, polyether silicones and cationic silicones, and mixtures thereof. The thickener(s) may be present in a composition according to the invention in a content ranging from 0.05% to 5.0% by weight, in particular from 0.3% to 4.0% by weight, more particularly from 0.4% to 2.5% by weight, relative to the total weight of the composition. Adjuvants A composition according to the invention may also include at last one adjuvant that is common in the cosmetic field, chosen from fragrances, film-forming polymers, pH adjusters (acid or base), for example citric acid, tartaric acid or oxalic acid, chelating agents, preserving agents, softeners, sweeteners, antifoaming agents, fillers, trace elements, propellants, and mixtures thereof. It is understood that those skilled in the art will take care to select this or these optional additional compound(s), and/or the amount thereof, such that the advantageous properties of a composition according to the invention are not, or are not substantially, adversely affected by the envisaged addition. It is understood that those skilled in the art will take care to select this or these optional additional compound(s), and/or the amount thereof, such that the advantageous properties of the particles according to the invention are not, or are not substantially, adversely affected by the envisaged addition. As stated previously, a composition according to the invention may be cosmetic, and preferably is cosmetic. A composition according to the invention is generally suitable for topical application to the skin and thus generally comprises a physiologically acceptable medium, i.e. a medium that is compatible with the skin. It is preferably a cosmetically acceptable medium, i.e. a medium which has a pleasant color, odor and feel and which does not cause any unacceptable discomfort, i.e. stinging or tautness, liable to discourage the user from applying this composition. Presentation forms of the compositions The compositions, notably cosmetic compositions, containing the particles according to the invention, may be prepared according to techniques that are well known to those skilled in the art. They may be in any conventional presentation form depending on the targeted applications and are suitable for topical application, i.e. application to the surface of the keratin materials under consideration. The cosmetic compositions may be in the form of an aqueous or aqueous-alcoholic gel. They may be in the form of a simple or complex emulsion (O/W, W/O, O/W/O or W/O/W), such as a cream, a milk or a gel-cream. They may also be in anhydrous form, for example in the form of an oil. The term “anhydrous composition” means a composition containing less than 5% by weight of water, or even less than 2% of water, better still less than 1% of water and notably being free of water, the water not being added during the preparation of the composition but corresponding to the residual water provided by the mixed ingredients. The cosmetic compositions may for example be used as a makeup product. The cosmetic compositions may be used, for example, as care and/or sun protection products for the face and/or body, of liquid to semi-liquid consistency, and may have the appearance of a more or less unctuous white or colored cream, an ointment, a milk, a cream-gel, a lotion, a serum, a paste or a foam. It may optionally be applied to the skin in aerosol form. It may also be in solid form, for example in the form of a stick. The cosmetic compositions may be in the form of products for caring for the skin or semi- mucous membranes, such as a protective or cosmetic care composition for the face, for the lips, for the hands, for the feet, for the anatomical folds or for the body (for example, day creams, night cream, day serum, night serum, makeup-removing cream, makeup base, protective or care body milk, after sun milk, skincare or scalp-care lotion, gel or foam, serum, mask, or aftershave composition). The composition may be applied by hand or using an applicator. In particular, the cosmetic compositions have an SPF of greater than 5 and preferably greater than 10. For the purposes of the invention, the term “SPF” means the sun protection factor, which measures the level of protection from UV rays. The SPF value corresponds to the ratio between the minimum time required to obtain an (erythematogenic) sunburn with a sun protection composition and the minimum time without a sun protection composition to obtain said sunburn. More specifically, the term “SPF” is defined in the article “A new substrate to measure sunscreen protection factors across the ultraviolet spectrum”, J. Soc. Cosmet. Chem., 40, 127-133 (May/June 1989). The SPF (Sun Protection Factor) may be evaluated in vitro using a Labsphere® spectrophotometer. The sheet is the material onto which the sun protection composition is applied. Poly(methyl methacrylate) (PMMA) sheets have proven to be ideal for this protocol. The Sun Protection Factor (SPF) of the compositions may also be evaluated in vivo in accordance with the ISO 24444 protocol “Cosmetics - Sun protection test methods - in vivo determination of the Sun Protection Factor (SPF) (2010)”. The term “UVAPF” means the index characterizing protection from UV-A radiation. In particular, it was possible to measure this index in vivo using the PPD (Persistent Pigment Darkening) method: “PPD” measures the color of the skin observed 2 to 4 hours after exposure to UV-A rays. This method has been adopted since 1996 by the Japan Cosmetic Industry Association (JCIA) as the official test procedure for UV-A labelling of products, and is frequently used by test laboratories in Europe and the United States (Japan Cosmetic Industry Association Technical Bulletin. Measurement standards for the efficacy of UVA protection issued on 21 November 1995 and in force since 1 January 1996). The UV-A protection can also be evaluated in vitro using the Labsphere® spectrophotometer. The sheet is the material onto which the sun protection composition is applied. For this protocol, polymethyl methacrylate (PMMA) sheets have proven to be ideal. The ISO 24443 protocol describes such an in vitro method. COSMETIC USES AND PROCESSES The present invention also relates to the non-therapeutic cosmetic use of the composite materials according to the invention for filtering UV radiation, preferably UV-B radiation, comprising at least the application to keratin materials of a composition comprising at least one composite material as defined previously. The present invention also relates to a non-therapeutic cosmetic process for filtering UV radiation, in particular UV-B radiation, comprising at least the application to keratin materials of a composition comprising at least one composite material as defined previously. According to yet another aspect thereof, the present invention also relates to the non- therapeutic cosmetic use of a cosmetic composition comprising at least one composite material defined previously, for preventing the appearance on the skin, in particular on the face, the neckline, the arms, the hands and/or the shoulders, of darker and/or more colored marks which give the skin a non-uniform color. The present invention is also directed towards a non-therapeutic cosmetic process for limiting the darkening of keratin materials, notably human keratin materials such as the skin, and/or of keratin fibers, notably human keratin fibers such as the hair, and/or for improving the color and/or uniformity of the complexion or of the keratin fibers, comprising the application to the surface of said keratin materials and/or of said keratin fibers of at least one cosmetic composition comprising at least one composite material defined previously. The present invention is also directed towards the non-therapeutic cosmetic use of a cosmetic composition comprising at least one composite material defined previously, for preventing premature ageing of the keratin materials, notably human keratin materials such as the skin, notably the skin of the face, the neckline, the arms, the hands and/or the shoulders. The invention also relates to a non-therapeutic cosmetic process for preventing and/or treating the signs of ageing of a keratin material, notably a human keratin material, notably the skin, comprising the application to the surface of the keratin material of at least one cosmetic composition comprising at least one composite material defined previously. According to one of its aspects, the present invention relates to the composite materials as defined previously, for use as agents for filtering UV radiation, in particular UV-B radiation. For the purposes of the present invention, the term “preventing” or “prevention” means reducing, at least in part, the risk of occurrence of a given phenomenon, for example the signs of ageing of a keratin material, notably a human keratin material such as the skin, or the appearance on said keratin material, notably human keratin material such as the skin, of darker and/or more colored marks which give the skin a non-uniform color and/or which prematurely age the skin. In the description and the examples, the percentages are weight or molar percentages. The ingredients are mixed in order and under conditions that are readily determined by a person skilled in the art. The invention will now be described by means of the following examples, which are of course given as non-limiting illustrations of the invention. Example Example 1: Preparation of the bismuth oxycarbonate particles according to the invention The bismuth oxycarbonate particles 1 and 2 are synthesized according to the preparation methods described below in Examples 1.A and 1.B. The morphology of the bismuth oxycarbonate particles was determined by direct observation by transmission electron microscopy.1 to 5 milligrams of dry particles are dispersed in 10 mL of absolute ethanol and treated in an ultrasound bath for two minutes.5 µL of dispersion are then placed on an observation grid (copper with surface layer of carbon) and dried in ambient air. The observation is performed using a Hitachi HT 7700 transmission electron microscope at an acceleration voltage of 100 kV. The mean dimensions are obtained by measurement of the dimensions of the particles by image analysis using the ImageJ software (C.A. Schneider, W.S. Rasband, K.W. Eliceiri, NIH Image to ImageJ: 25 years of image analysis, Nat. Methods.9 (2012) 671–675). Example 1.A: Synthesis of the bismuth oxycarbonate particles 1 A solution of bismuth nitrate pentahydrate Bi(NO3)3·5H2O (0.40 M) and of D-mannitol (2 M) is prepared in 800 mL of water and stirred until the reagents have completely dissolved.160 mL of ammonium carbonate solution (2.1 equivalents relative to the bismuth) are then added. A white solid precipitates. After 30 minutes, this mixture is then transferred into a Teflon autoclave reactor and heated for 12 hours at 150 °C. Bismuth oxycarbonate particles 1 are isolated by centrifugation and washed three times with water before being oven-dried at 60 °C. The bismuth oxycarbonate particles 1 are platelets having the following mean dimensions: Mean length L: 85 nm Mean width l: 52 nm Mean thickness e: 28 nm Example 1.B: Synthesis of the bismuth oxycarbonate particles 2 A solution of bismuth nitrate pentahydrate Bi(NO3)3·5H2O (0.40 M) and of D-mannitol (0.87 M) is prepared in 800 mL of water and stirred until the reagents have completely dissolved. 160 mL of ammonium carbonate solution (2.1 equivalents relative to the bismuth) are then added. A white solid precipitates. This mixture is then transferred into a Teflon autoclave reactor and heated for 7.5 hours at 125 °C. Product 2 is isolated by centrifugation and washed three times with water before being oven-dried at 60 °C. The bismuth oxycarbonate particles 2 are platelets having the following mean dimensions: Mean length L: 86 nm Mean width l: 53 nm Mean thickness e: 28 nm Example 2: Syntheses of the composite materials according to the invention Example 2.A1: Synthesis by atomization of bismuth oxycarbonate/carrageenan composite materials at a mass ratio equal to 1.66 A solution of carrageenan (INCI name CARRAGEENAN) (0.6 g) in 100 mL of water is heated to 80 °C and stirred until the polymer has completely dissolved. The medium is then cooled to room temperature. 1 g of bismuth oxycarbonate particles according to Example 1A is added to this solution, and the suspension is ultrasonicated for 15 minutes, then stirred overnight at room temperature. The white dispersion obtained is then atomized at 150 °C, with a pumping rate of 15%, a suction rate of 80% and 2 nozzles (apparatus type: BUCHI B-290 Mini Spray Dryer). Composite material A1 is isolated in the form of a white powder and is characterized by UV/Vis spectrophotometry. Example 2.A2: Synthesis by atomization of bismuth oxycarbonate/carrageenan composite materials at a mass ratio equal to 0.5 A solution of carrageenan (INCI name CARRAGEENAN) (2 g) in 100 mL of water is heated to 80 °C and stirred until the polymer has completely dissolved. The viscous medium is then cooled to room temperature. 1 g of bismuth oxycarbonate particles according to Example 1A is added to this viscous solution, and the suspension is ultrasonicated for 15 minutes, then stirred overnight at room temperature. The white dispersion obtained is then atomized at 150 °C, with a pumping rate of 15%, a suction rate of 80% and 4 nozzles (apparatus type: BUCHI B-290 Mini Spray Dryer). Composite material A2 is isolated in the form of a white-beige powder and is characterized by UV/Vis spectrophotometry. Example 2.B1: Synthesis by lyophilization of bismuth oxycarbonate/carrageenan composite materials at a mass ratio equal to 1.66 A solution of carrageenan (INCI name CARRAGEENAN) (0.6 g) in 100 mL of water is heated to 80 °C and stirred until the polymer has completely dissolved. The medium is then cooled to room temperature. 1 g of bismuth oxycarbonate particles according to Example 1A is added to this solution, and the suspension is ultrasonicated for 15 minutes, then stirred overnight. The white dispersion obtained is then lyophilized. Composite material B1 is isolated in the form of a white solid and is characterized by UV/Vis spectrophotometry. Example 2.B2: Synthesis by lyophilization of bismuth oxycarbonate/carrageenan composite materials at a mass ratio equal to 4.16 A solution of carrageenan (INCI name CARRAGEENAN) (0.24 g) in 100 mL of water is heated to 80 °C and stirred until the polymer has completely dissolved. The medium is then cooled to room temperature. 1 g of bismuth oxycarbonate particles according to Example 1A is added to this solution, and the suspension is ultrasonicated for 15 minutes, then stirred overnight. The white dispersion obtained is then lyophilized. Composite material B2 is isolated in the form of a white solid and is characterized by UV/Vis spectrophotometry. Example 2.C1: Synthesis by centrifugation of bismuth oxycarbonate/carrageenan composite materials at a mass ratio equal to 1.66 A solution of carrageenan (INCI name CARRAGEENAN) (0.6 g) in 100 mL of water is heated to 80 °C and stirred until the polymer has completely dissolved. The medium is then cooled to room temperature. 1 g of bismuth oxycarbonate particles according to Example 1A is added to this solution, and the suspension is ultrasonicated for 15 minutes, then stirred overnight. The white dispersion obtained is then centrifuged. The pellet is washed with ethanol and centrifuged again. The solid obtained is oven-dried under vacuum at 50 °C. Composite material C1 is isolated in the form of a white powder and is characterized by UV/Vis spectrophotometry. Example 2.C2: Synthesis by precipitation/centrifugation of bismuth oxycarbonate/carrageenan composite materials at a mass ratio equal to 1.66 A solution of carrageenan (INCI name CARRAGEENAN) (0.6 g) in 100 mL of water is heated to 80 °C and stirred until the polymer has completely dissolved. The medium is then cooled to room temperature. 1 g of bismuth oxycarbonate particles according to Example 1A is added to this solution, and the suspension is ultrasonicated for 15 minutes, then stirred overnight. The white dispersion obtained is precipitated using 4 volumes of ethanol, and is then centrifuged. The solid obtained is oven-dried under vacuum at 50 °C. Composite material C2 is isolated in the form of a white powder and is characterized by UV/Vis spectrophotometry. Example 2.C3: Synthesis by precipitation/centrifugation of bismuth oxycarbonate/carrageenan composite materials at a mass ratio equal to 1.66 A solution of carrageenan (INCI name CARRAGEENAN) (0.6 g) in 100 mL of water is heated to 80 °C and stirred until the polymer has completely dissolved. The medium is then cooled to room temperature. 1 g of bismuth oxycarbonate particles according to Example 1A is added to this solution, and the suspension is ultrasonicated for 15 minutes, then stirred overnight. The white dispersion obtained is precipitated using 4 volumes of ethanol, and is then centrifuged. The solid obtained is oven-dried under vacuum at 50 °C. Composite material C3 is isolated in the form of a white powder and is characterized by UV/Vis spectrophotometry. Example 2.C4: Synthesis by precipitation/centrifugation of bismuth oxycarbonate/carrageenan composite materials at a mass ratio equal to 1.66 A solution of carrageenan (INCI name CARRAGEENAN) (0.6 g) in 100 mL of water is heated to 80 °C and stirred until the polymer has completely dissolved. The medium is then cooled to room temperature. 1 g of bismuth oxycarbonate particles according to Example 1A is added to this solution, and the suspension is ultrasonicated for 15 minutes, then stirred overnight. The white dispersion obtained is precipitated using 10 volumes of ethanol, and is then centrifuged. The solid obtained is oven-dried under vacuum at 50 °C. Composite material C4 is isolated in the form of a white powder and is characterized by UV/Vis spectrophotometry. Example 2.D: Synthesis by atomization of bismuth oxycarbonate/carrageenan composite materials at a mass ratio equal to 1.66 A solution of carrageenan (INCI name CARRAGEENAN) (0.6 g) in 100 mL of water is heated to 80 °C and stirred until the polymer has completely dissolved. The medium is then cooled to room temperature. 1 g of bismuth oxycarbonate particles according to Example 1A is added to this solution, and the suspension is ultrasonicated for 15 minutes, then stirred overnight. The white dispersion obtained is then atomized at 150 °C, with a pumping rate of 15%, a suction rate of 80% and 5 nozzles (apparatus type: BUCHI B-290 Mini Spray Dryer). Composite material D is isolated in the form of a white powder and is characterized by UV/Vis spectrophotometry. Example 2.E1: Synthesis by lyophilization of bismuth oxycarbonate/carrageenan composite materials at a mass ratio equal to 1.66 A solution of carrageenan (INCI name CARRAGEENAN) (0.6 g) in 100 mL of water is heated to 80 °C and stirred until the polymer has completely dissolved. The medium is then cooled to room temperature. 1 g of bismuth oxycarbonate particles according to Example 1A is added to this solution, and the suspension is ultrasonicated for 15 minutes, then stirred overnight. The white dispersion obtained is then lyophilized. Composite material E1 is isolated in the form of a white solid and is characterized by UV/Vis spectrophotometry. Example 2.E2: Synthesis by lyophilization of bismuth oxycarbonate/carrageenan composite materials at a mass ratio equal to 4.16 A solution of carrageenan (INCI name CARRAGEENAN) (0.24 g) in 100 mL of water is heated to 80 °C and stirred until the polymer has completely dissolved. The medium is then cooled to room temperature. 1 g of bismuth oxycarbonate particles according to Example 1A is added to this solution, and the suspension is ultrasonicated for 15 minutes, then stirred overnight. The white dispersion obtained is then lyophilized. Composite material E2 is isolated in the form of a white solid and is characterized by UV/Vis spectrophotometry. Example 2.F1: Synthesis by centrifugation of bismuth oxycarbonate/carrageenan composite materials at a mass ratio equal to 1.66 A solution of carrageenan (INCI name CARRAGEENAN) (0.6 g) in 100 mL of water is stirred until the polymer has completely dissolved. The medium is then cooled to room temperature. 1 g of bismuth oxycarbonate particles according to Example 1A is added to this solution, and the suspension is ultrasonicated for 15 minutes, then stirred overnight. The white dispersion obtained is then centrifuged, washed with ethanol and centrifuged again. The solid obtained is oven-dried under vacuum at 50 °C. Composite material F1 is isolated in the form of a white powder and is characterized by UV/Vis spectrophotometry. Example 2.F2: Synthesis by precipitation/centrifugation of bismuth oxycarbonate/carrageenan composite materials at a mass ratio equal to 1.66 A solution of carrageenan (INCI name CARRAGEENAN) (0.6 g) in 100 mL of water is stirred until the polymer has completely dissolved. The medium is then cooled to room temperature. 1 g of bismuth oxycarbonate particles according to Example 1A is added to this solution, and the suspension is ultrasonicated for 15 minutes, then stirred overnight. The white dispersion obtained is precipitated using 4 volumes of ethanol, and is then centrifuged. The solid obtained is oven-dried under vacuum at 50 °C. Composite material F2 is isolated in the form of a white powder and is characterized by UV/Vis spectrophotometry. Example 2.G: Synthesis by atomization of bismuth oxycarbonate/calcium lignosulfonate composite materials at a mass ratio equal to 0.71 A solution of calcium lignosulfonate (DP25228, sold by Borregaard) (1.4 g) in 100 mL of water is stirred until the polymer has completely dissolved. 1 g of bismuth oxycarbonate particles according to Example 1A is added to this solution, and the suspension is ultrasonicated for 15 minutes, then stirred overnight. The light beige dispersion obtained is then atomized at 120 °C, with a pumping rate of 15%, a suction rate of 80% and 5 nozzles (apparatus type: BUCHI B-290 Mini Spray Dryer). Composite material G is isolated in the form of a beige powder and is characterized by UV/Vis spectrophotometry. Example 2.H1: Synthesis by lyophilization of bismuth oxycarbonate/calcium lignosulfonate composite materials at a mass ratio equal to 0.71 A solution of calcium lignosulfonate (DP25228, sold by Borregaard) (1.4 g) in 100 mL of water is stirred until the polymer has completely dissolved. 1 g of bismuth oxycarbonate particles according to Example 1A is added to this solution, and the suspension is ultrasonicated for 15 minutes, then stirred overnight. The light beige dispersion is then lyophilized. Composite material H1 is isolated in the form of a downy white solid and is characterized by UV/Vis spectrophotometry. Example 2.H2: Synthesis by lyophilization of bismuth oxycarbonate/calcium lignosulfonate composite materials at a mass ratio equal to 1.78 A solution of calcium lignosulfonate (DP25228, sold by Borregaard) (0.56 g) in 100 mL of water is stirred until the polymer has completely dissolved. 1 g of bismuth oxycarbonate particles according to Example 1A is added to this solution, and the suspension is ultrasonicated for 15 minutes, then stirred overnight. The light beige dispersion is then lyophilized. Composite material H2 is isolated in the form of a downy white solid and is characterized by UV/Vis spectrophotometry. Example 2.I: Synthesis by atomization of bismuth oxycarbonate/sodium lignosulfonate composite materials at a mass ratio equal to 0.71 A solution of sodium lignosulfonate (DP25230, sold by Borregaard) (1.4 g) in 100 mL of water is stirred until the polymer has completely dissolved. 1 g of bismuth oxycarbonate particles according to Example 1B is added to this solution, and the suspension is ultrasonicated for 15 minutes, then stirred overnight. The light beige dispersion obtained is then atomized at 120 °C, with a pumping rate of 15%, a suction rate of 80% and 5 nozzles (apparatus type: BUCHI B-290 Mini Spray Dryer). Composite material I is isolated in the form of a beige powder and is characterized by UV/Vis spectrophotometry. Example 2.J1: Synthesis by lyophilization of bismuth oxycarbonate/sodium lignosulfonate composite materials at a mass ratio equal to 0.71 A solution of sodium lignosulfonate (DP25230, sold by Borregaard) (1.4 g) in 100 mL of water is stirred until the polymer has completely dissolved. 1 g of bismuth oxycarbonate particles according to Example 1B is added to this solution, and the suspension is ultrasonicated for 15 minutes, then stirred overnight. The light beige dispersion is then lyophilized. Composite material J1 is isolated in the form of a downy white solid and is characterized by UV/Vis spectrophotometry. Example 2.J2: Synthesis by lyophilization of bismuth oxycarbonate/sodium lignosulfonate composite materials at a mass ratio equal to 1.78 A solution of sodium lignosulfonate (DP25230, sold by Borregaard) (0.56 g) in 100 mL of water is stirred until the polymer has completely dissolved. 1 g of bismuth oxycarbonate particles according to Example 1B is added to this solution, and the suspension is ultrasonicated for 15 minutes, then stirred overnight. The light beige dispersion is then lyophilized. Composite material J2 is isolated in the form of a downy white solid and is characterized by UV/Vis spectrophotometry. Example 2.K: Synthesis by atomization of bismuth oxycarbonate/chitosan composite materials at a mass ratio equal to 0.6 A solution of chitosan (Kiosmetine-CSG sold by Kitozyme) (1.64 g) in 100 mL of water is adjusted to pH 4 with lactic acid, then is stirred until the polymer has completely dissolved. 1 g of bismuth oxycarbonate particles according to Example 1A is added to this solution, and the suspension is ultrasonicated for 15 minutes, then stirred overnight. The light beige dispersion obtained is then atomized at 160 °C, with a pumping rate of 15%, a suction rate of 80% and 5 nozzles (apparatus type: BUCHI B-290 Mini Spray Dryer). Composite material K is isolated in the form of a beige powder and is characterized by UV/Vis spectrophotometry. Example 2.L1: Synthesis by lyophilization of bismuth oxycarbonate/chitosan composite materials at a mass ratio equal to 0.6 A solution of chitosan (Kiosmetine-CSG sold by Kitozyme) (1.64 g) in 100 mL of water is adjusted to pH 4 with lactic acid, then is stirred until the polymer has completely dissolved. 1 g of bismuth oxycarbonate particles according to Example 1B is added to this solution, and the suspension is ultrasonicated for 15 minutes, then stirred overnight. The light beige dispersion is then lyophilized. Composite material L1 is isolated in the form of a beige powder and is characterized by UV/Vis spectrophotometry. Example 2.L2: Synthesis by lyophilization of bismuth oxycarbonate/chitosan composite materials at a mass ratio equal to 1.51 A solution of chitosan (Kiosmetine-CSG sold by Kitozyme) (0.66 g) in 100 mL of water is adjusted to pH 4 with lactic acid, then is stirred until the polymer has completely dissolved. 1 g of bismuth oxycarbonate particles according to Example 1B is added to this solution, and the suspension is ultrasonicated for 15 minutes, then stirred overnight. The light beige dispersion is then lyophilized. Composite material L2 is isolated in the form of a beige powder and is characterized by UV/Vis spectrophotometry. Example 2.M: Synthesis by atomization of bismuth oxycarbonate/sodium alginate composite materials at a mass ratio equal to 1.06 A solution of sodium alginate (0.94 g) in 100 mL of water is heated to 40 °C and stirred until the polymer has completely dissolved. The medium is then cooled to room temperature. 1 g of bismuth oxycarbonate particles according to Example 1A is added to this solution, and the suspension is ultrasonicated for 15 minutes, then stirred overnight. The white dispersion obtained is then atomized at 160 °C, with a pumping rate of 15%, a suction rate of 80% and 2 nozzles (apparatus type: BUCHI B-290 Mini Spray Dryer). Composite material M is isolated in the form of a white powder and is characterized by UV/Vis spectrophotometry. Example 2.N1: Synthesis by lyophilization of bismuth oxycarbonate/sodium alginate composite materials at a mass ratio equal to 1.06 A solution of sodium alginate (0.94 g) in 100 mL of water is heated to 80 °C and stirred until the polymer has completely dissolved. The medium is then cooled to room temperature. 1 g of bismuth oxycarbonate particles according to Example 1A is added to this solution, and the suspension is ultrasonicated for 15 minutes, then stirred overnight. The white dispersion obtained is then lyophilized. Composite material N1 is isolated in the form of a downy white solid and is characterized by UV/Vis spectrophotometry. Example 2.N2: Synthesis by lyophilization of bismuth oxycarbonate/sodium alginate composite materials at a mass ratio equal to 2.7 A solution of sodium alginate (0.37 g) in 100 mL of water is heated to 80 °C and stirred until the polymer has completely dissolved. The medium is then cooled to room temperature. 1 g of bismuth oxycarbonate particles according to Example 1A is added to this solution, and the suspension is ultrasonicated for 15 minutes, then stirred overnight. The white dispersion obtained is then lyophilized. Composite material N2 is isolated in the form of a downy white solid and is characterized by UV/Vis spectrophotometry. Example 2.O1: Synthesis by isolation (centrifugation) of bismuth oxycarbonate/sodium alginate composite materials at a mass ratio equal to 1.06 A solution of sodium alginate (0.94 g) in 100 mL of water is stirred until the polymer has completely dissolved. The medium is then cooled to room temperature. 1 g of bismuth oxycarbonate particles according to Example 1A is added to this solution, and the suspension is ultrasonicated for 15 minutes, then stirred overnight. The white dispersion obtained is then centrifuged, washed with ethanol and centrifuged again. The solid obtained is oven-dried under vacuum at 50 °C. Composite material O1 is isolated in the form of a white powder and is characterized by UV/Vis spectrophotometry. Example 2.O2: Synthesis by centrifugation of bismuth oxycarbonate/sodium alginate composite materials at a mass ratio equal to 1.06 A solution of sodium alginate (0.94 g) in 100 mL of water is heated to 80 °C and stirred until the polymer has completely dissolved. The medium is then cooled to room temperature. 1 g of bismuth oxycarbonate particles according to Example 1A is added to this solution, and the suspension is ultrasonicated for 15 minutes, then stirred overnight. The white dispersion obtained is heated at 55 °C for 1 h 30 and allowed to return to room temperature, then is centrifuged, washed with ethanol and centrifuged again. The solid obtained is oven- dried under vacuum at 50 °C. Composite material O2 is isolated in the form of a white powder and is characterized by UV/Vis spectrophotometry. Example 2.P1: Synthesis by atomization of bismuth oxycarbonate/sodium dextran sulfate composite materials at a mass ratio equal to 0.9 A solution of sodium dextran sulfate (Dextralip 10C, sold by Safic-Alcan) (1.1 g) in 100 mL of water is stirred until the polymer has completely dissolved. 1 g of bismuth oxycarbonate particles according to Example 1B is added to this solution, the suspension is ultrasonicated for 15 minutes, then stirred overnight. The white dispersion is then atomized at 120 °C, with a pumping rate of 15%, a suction rate of 80% and 4 nozzles (apparatus type: BUCHI B-290 Mini Spray Dryer). Composite material P1 is isolated in the form of a beige powder and is characterized by UV/Vis spectrophotometry. Example 2.P2: Synthesis by atomization of bismuth oxycarbonate/sodium dextran sulfate composite materials at a mass ratio equal to 8.33 A solution of sodium dextran sulfate (Dextralip 10C, sold by Safic-Alcan) (0.12 g) in 100 mL of water is stirred until the polymer has completely dissolved. 1 g of bismuth oxycarbonate particles according to Example 1B is added to this solution, the suspension is ultrasonicated for 15 minutes, then stirred overnight. The white dispersion is then atomized at 120 °C, with a pumping rate of 15%, a suction rate of 80% and 2 nozzles (apparatus type: BUCHI B-290 Mini Spray Dryer). Composite material P2 is isolated in the form of a beige powder and is characterized by UV/Vis spectrophotometry. Example 2.Q1: Synthesis by lyophilization of bismuth oxycarbonate/sodium dextran sulfate composite materials at a mass ratio equal to 0.9 A solution of sodium dextran sulfate (Dextralip 10C, sold by Safic-Alcan) (1.1 g) in 100 mL of water is stirred until the polymer has completely dissolved. 1 g of bismuth oxycarbonate particles according to Example 1B is added to this solution, the suspension is ultrasonicated for 15 minutes, then stirred overnight. The white dispersion is then lyophilized. Composite material Q1 is isolated in the form of a downy white solid and is characterized by UV/Vis spectrophotometry. Example 2.Q2: Synthesis by lyophilization of bismuth oxycarbonate/sodium dextran sulfate composite materials at a mass ratio equal to 2.27 A solution of sodium dextran sulfate (Dextralip 10C, sold by Safic-Alcan) (0.44 g) in 100 mL of water is stirred until the polymer has completely dissolved. 1 g of bismuth oxycarbonate particles according to Example 1B is added to this solution, the suspension is ultrasonicated for 15 minutes, then stirred overnight. The white dispersion is then lyophilized. Composite material Q2 is isolated in the form of a downy white solid and is characterized by UV/Vis spectrophotometry. Example 2.R: Synthesis by atomization of bismuth oxycarbonate/polyvinyl alcohol composite materials at a mass ratio equal to 0.84 A solution of polyvinyl alcohol (Mowiol 8-88, sold by Sigma Aldrich) (1.19 g) in 100 mL of water is heated to 80 °C and stirred until the polymer has completely dissolved. The medium is then cooled to room temperature. 1 g of bismuth oxycarbonate particles according to Example 1B is added to this solution, and the suspension is ultrasonicated for 15 minutes, then stirred overnight. The white dispersion obtained is then atomized at 120 °C, with a pumping rate of 15%, a suction rate of 80% and 3 nozzles (apparatus type: BUCHI B-290 Mini Spray Dryer). Composite material R is isolated in the form of a white powder and is characterized by UV/Vis spectrophotometry. Example 2.S1: Synthesis by lyophilization of bismuth oxycarbonate/polyvinyl alcohol composite materials at a mass ratio equal to 0.84 A solution of polyvinyl alcohol (Mowiol 8-88, sold by Sigma Aldrich) (1.19 g) in 100 mL of water is heated to 80 °C and stirred until the polymer has completely dissolved. The medium is then cooled to room temperature. 1 g of bismuth oxycarbonate particles according to Example 1B is added to this solution, and the suspension is ultrasonicated for 15 minutes, then stirred overnight. The white dispersion obtained is lyophilized. Composite material S1 is isolated in the form of a downy white solid and is characterized by UV/Vis spectrophotometry. Example 2.S2: Synthesis by lyophilization of bismuth oxycarbonate/polyvinyl alcohol composite materials at a mass ratio equal to 2.12 A solution of polyvinyl alcohol (Mowiol 8-88, sold by Sigma Aldrich) (0.47 g) in 100 mL of water is heated to 80 °C and stirred until the polymer has completely dissolved. The medium is then cooled to room temperature. 1 g of bismuth oxycarbonate particles according to Example 1B is added to this solution, then the suspension is ultrasonicated for 15 minutes, then stirred overnight. The white dispersion obtained is then lyophilized. Composite material S2 is isolated in the form of a downy white solid and is characterized by UV/Vis spectrophotometry. Example 2.T: Synthesis by precipitation/centrifugation of bismuth oxycarbonate/polyhydroxystearic acid composite materials at a mass ratio equal to 2.12 A solution of polyhydroxystearic acid (INCI name: POLYHYDROXYSTEARIC ACID) (0.84 g) in 50 mL of acetone is heated to 50 °C and stirred until the polymer has completely dissolved. A suspension of 1 g of bismuth oxycarbonate particles according to Example 1B in 50 mL of acetone is ultrasonicated for 15 minutes, then is added to the polymer solution at 50 °C, then is stirred overnight at room temperature. The white dispersion obtained is then centrifuged. The pellet is washed with acetone and centrifuged again. The solid obtained is oven-dried under vacuum at 50 °C. The white dispersion obtained is then lyophilized. Composite material T is isolated in the form of a white powder and is characterized by UV/Vis spectrophotometry. Example 2.U: Synthesis by lyophilization of bismuth oxycarbonate not in accordance with the invention/sodium dextran sulfate composite materials at a mass ratio equal to 0.9 A solution of sodium dextran sulfate (Dextralip 10C, sold by Safic-Alcan) (1.1 g) in 100 mL of water is stirred until the polymer has completely dissolved. 1 g of bismuth oxycarbonate particles not in accordance with the invention (500 nm in length, 50 nm in width) are added to this solution. The suspension is ultrasonicated for 15 minutes, then stirred overnight. The white dispersion is then lyophilized. Composite material U is isolated in the form of a downy white solid and is characterized by UV/Vis spectrophotometry. Example 2.V: Synthesis by lyophilization of bismuth oxycarbonate/ pregelatinized hydroxypropyl corn distarch phosphate composite materials at a mass ratio equal to 1.1 A solution of pregelatinized hydroxypropyl corn distarch phosphate (INCI name: HYDROXYPROPYL STARCH PHOSPHATE) (0.93 g) in 100 mL of water is heated to 95 °C and stirred until the polymer has completely dissolved. Thereafter, the medium is cooled to room temperature. 1 g of bismuth oxycarbonate particles according to Example 1A is added to this solution, and the suspension is ultrasonicated for 15 minutes, then stirred overnight. The white dispersion obtained is lyophilized. Composite material V is isolated in the form of a downy beige solid and is characterized by UV/Vis spectrophotometry. Example 2.W: Synthesis by lyophilization of bismuth oxycarbonate/ pregelatinized hydroxypropyl corn distarch phosphate composite particles at a mass ratio equal to 2.7 A solution of pregelatinized hydroxypropyl corn distarch phosphate (INCI name: HYDROXYPROPYL STARCH PHOSPHATE) (0.37 g) in 100 mL of water is heated to 95 °C and stirred until the polymer has completely dissolved. Thereafter, the medium is cooled to room temperature. 1 g of bismuth oxycarbonate particles according to Example 1A is added to this solution, and the suspension is ultrasonicated for 15 minutes, then stirred overnight. The white dispersion obtained is lyophilized. Composite material W is isolated in the form of a downy beige solid and is characterized by UV/Vis spectrophotometry. Example 2.X: Synthesis by atomization of bismuth oxycarbonate/pullulan composite particles at a mass ratio equal to 0.71 A solution of pullulan (sold by HAYASHIBARA) (1.4 g) in 100 mL of water is stirred until the polymer has completely dissolved. 1 g of bismuth oxycarbonate particles according to Example 1A is added to this solution, and the suspension is ultrasonicated for 15 minutes, then stirred overnight. The white dispersion obtained is then atomized at 130 °C, with a pumping rate of 15%, a suction rate of 80% and 2 nozzles (apparatus type: BUCHI B-290 Mini Spray Dryer). Composite material X is isolated in the form of a white powder and is characterized by UV/Vis spectrophotometry. Example 2.Y: Synthesis by lyophilization of bismuth oxycarbonate/pullulan composite particles at a mass ratio equal to 0.71 A solution of pullulan (sold by HAYASHIBARA) (1.4 g) in 100 mL of water is stirred until the polymer has completely dissolved. 1 g of bismuth oxycarbonate particles according to Example 1A is added to this solution, and the suspension is ultrasonicated for 15 minutes, then stirred overnight. The white dispersion obtained is lyophilized. Composite material Y is isolated in the form of a downy white solid and is characterized by UV/Vis spectrophotometry. Example 2.Z: Synthesis by lyophilization of bismuth oxycarbonate/pullulan composite particles at a mass ratio equal to 1.78 A solution of pullulan (sold by HAYASHIBARA) (0.56 g) in 100 mL of water is stirred until the polymer has completely dissolved. 1 g of bismuth oxycarbonate particles according to Example 1A is added to this solution, and the suspension is ultrasonicated for 15 minutes, then stirred overnight. The white dispersion obtained is lyophilized. Composite material Z is isolated in the form of a downy white solid and is characterized by UV/Vis spectrophotometry. Example 2. AA - Synthesis by centrifugation of bismuth oxycarbonate/myristoyl pullulan composite particles at a mass ratio equal to 0.71 A solution of myristoyl pullulan (sold by Katakura Chikkarin) (1.4 g) in 100 mL of isododecane is stirred until the polymer has completely dissolved. 1 g of bismuth oxycarbonate particles according to Example 1A is added to this solution, and the suspension is ultrasonicated for 15 minutes, then stirred overnight. The white dispersion obtained is centrifuged, washed with ethanol and centrifuged again. The solid obtained is oven-dried under vacuum at 50 °C. Composite material AA is isolated in the form of a white powder and is characterized by UV/Vis spectrophotometry. Example 2.DD: Synthesis by atomization of bismuth oxycarbonate/hydrolyzed soy protein composite particles at a mass ratio equal to 2 A solution of soy protein (INCI name Hydrolyzed soy protein) (0.5 g) in 100 mL of water is stirred until the polymer has completely dissolved. 1 g of bismuth oxycarbonate particles according to Example 1A is added to this solution, and the suspension is ultrasonicated for 15 minutes, then stirred overnight. The white dispersion obtained is then atomized at 150 °C, with a pumping rate of 15%, a suction rate of 80% and 9 nozzles (apparatus type: BUCHI B-290 Mini Spray Dryer). Composite material DD is isolated in the form of a white powder and is characterized by UV/Vis spectrophotometry. Example 2. EE: Combination of bismuth oxycarbonate particles with the sodium lignosulfonate polymer at a mass ratio equal to 0.71 A solution of sodium lignosulfonate (DP25230, sold by Borregaard) (14 mg) in 10 mL of water is stirred until the polymer has completely dissolved. 10 g of bismuth oxycarbonate particles according to Example 1B are added to this solution, and the suspension is ultrasonicated for 15 minutes, then stirred overnight. The product EE is characterized by UV/Vis spectrophotometry. Example 2. FF: Combination of bismuth oxycarbonate particles with the carrageenan polymer at a mass ratio equal to 1.66 A solution of carrageenan (INCI name CARRAGEENAN) (6 mg) in 10 mL of water is heated to 80 °C and stirred until the polymer has completely dissolved. The medium is then cooled to room temperature. 10 mg of bismuth oxycarbonate particles according to Example 1A are added to this solution, and the suspension is ultrasonicated for 15 minutes, then stirred overnight. The product FF is characterized by UV/Vis spectrophotometry. Example 2.HH: Synthesis by centrifugation of composite materials bismuth oxycarbonate/Ethyl AcetoAcetate polymer with a mass ratio of 1.06 A solution of ethyl AcetoAcetate polymer (INCI name: Ethyl acetoacetate) (0.935 g) in 100 ml of ethyl acetate is stirred until complete dissolution of the polymer. 1 g of bismuth oxycarbonate particles obtained according to example 1B, is added to this solution, and the dispersion is ultrasonicated for 15 min, then stirred for one night at room temperature. The resulting white dispersion is then evaporated at 40°C under vacuum and the obtained solid redispersed in 40 ml of ethyl acetate. The dispersion is then centrifuged and washed two times with ethyl acetate. The resulting solid is dried in an oven at 50°C. The HH composite material is isolated as a white powder and is characterized by UV/Vis spectrophotometry. Example 2.II: Synthesis by centrifugation of composite materials bismuth oxycarbonate/Ethyl AcetoAcetate with a mass ratio of 2.66 A solution of ethyl AcetoAcetate (INCI name: Ethyl acetoacetate) (0.376 g) in 100 ml of ethyl acetate is stirred until complete dissolution. 1 g of bismuth oxycarbonate particles obtained according to example 1B, is added to this solution, and the dispersion is ultrasonicated for 15 min, then stirred for one night at room temperature. The resulting white dispersion obtained is centrifuged and washed two times with ethyl acetate. The resulting solid is dried in an oven at 50°C. The II composite material is isolated as a white powder and is characterized by UV/Vis spectrophotometry. Example 2.JJ: Synthesis by centrifugation of composite materials bismuth oxycarbonate/PHN polymer with a mass ratio of 0.85 A solution of PHN polymer (Polyhydroxy Nonanoate) (1.17 g) in 100 ml of acetone is stirred until complete dissolution of the polymer. 1 g of bismuth oxycarbonate particles obtained according to example 1B, is added to the polymer solution, and the dispersion is ultrasonicated for 15 min, then stirred for one night at room temperature. The white dispersion is centrifuged and the resulting solid dried in an oven at 50°C The JJ composite material is isolated as a white powder and is characterized by UV/Vis spectrophotometry. Example 2. : Summary of the conditions for synthesizing materials A to JJ Table 1 below summarizes all the products prepared in Examples 2.A1 to 2.JJ. [Table 1] Composite Bismuth oxycarbonate Method Mass ratio or product particles/polymer A1 Atomization (BiO)₂CO₃/carrageenan 1.66 A2 Atomization (BiO)2CO3/carrageenan 0.5 B1 Lyophilization (BiO)₂CO₃/carrageenan 1.66 B2 Lyophilization (BiO)2CO3/carrageenan 4.16 C1 Centrifugation (BiO)₂CO₃/carrageenan 1.66 C2 Precipitation/Centrif (BiO)2CO3/carrageenan 1.66 ugation C3 Precipitation/Centrif (BiO)₂CO₃/carrageenan 1.66 ugation C4 Precipitation/Centrif (BiO)2CO3/carrageenan 1.66 ugation D Atomization (BiO)2CO3/carrageenan 1.66 E1 Lyophilization (BiO)2CO3/carrageenan 1.66 E2 Lyophilization (BiO)₂CO₃/carrageenan 4.16 F1 Centrifugation (BiO)2CO3/carrageenan 1.66 F2 Precipitation/Centrif (BiO)2CO3/carrageenan 1.66 ugation G Atomization (BiO)₂CO₃/Ca lignosulfonate 0.71 H1 Lyophilization (BiO)2CO3/Ca lignosulfonate 0.71 H2 Lyophilization (BiO)₂CO₃/Ca lignosulfonate 1.78 I Atomization (BiO)2CO3/Na lignosulfonate 0.71 J1 Lyophilization (BiO)₂CO₃/Na lignosulfonate 0.71 J2 Lyophilization (BiO)2CO3/Na lignosulfonate 1.78 K Atomization (BiO)₂CO₃/chitosan 0.6 L1 Lyophilization (BiO)2CO3/chitosan 0.6 L2 Lyophilization (BiO)₂CO₃/chitosan 1.51 M Atomization (BiO)2CO3/sodium alginate 1.06 N1 Lyophilization (BiO)2CO3/sodium alginate 1.06 N2 Lyophilization (BiO)2CO3/sodium alginate 2.7 O1 Centrifugation (BiO)2CO3/sodium alginate 1.06 O2 Centrifugation (BiO)₂CO₃/sodium alginate 1.06 P1 Atomization (BiO)2CO3/sodium dextran sulfate 0.9 P2 Atomization (BiO)₂CO₃/sodium dextran sulfate 8.33 Q1 Lyophilization (BiO)2CO3/sodium dextran sulfate 0.9 Q2 Lyophilization (BiO)₂CO₃/sodium dextran sulfate 2.27 R Atomization (BiO)2CO3/polyvinyl alcohol 0.84 S1 Lyophilization (BiO)₂CO₃/polyvinyl alcohol 0.84 S2 Lyophilization (BiO)2CO3/polyvinyl alcohol 2.12 T Precipitation/Centrif (BiO)₂CO₃/polyhydroxystearic acid 2.12 ugation (BiO)2CO3/sodium dextran sulfate with U Lyophilization (BiO)2CO3 not in accordance with 0.9 invention (BiO)₂CO₃/pregelatinized V Lyophilization 1.1 hydroxypropyl corn distarch phosphate (BiO)2CO3/pregelatinized W Lyophilization 2.7 hydroxypropyl corn distarch phosphate X Atomization (BiO)₂CO₃/pullulan 0.71 Y Lyophilization (BiO)2CO3/pullulan 0.71 Z Lyophilization (BiO)₂CO₃/pullulan 1.78 A Centrifugation (BiO)2CO3/myristoyl pullulan 0.71 DD Atomization (BiO)2CO3/hydrolyzed soy protein 2 EE Combination (BiO)2CO3 + Na lignosulfonate 0.71 FF Combination (BiO)₂CO₃ + carrageenan 1.66 HH Centrifugation (BiO)2CO3/Ethyl AcetoAcetate 1.06 II Centrifugation (BiO)₂CO₃/Ethyl AcetoAcetate 2.66 J^{J Centrifugation} _{(BiO)2CO3/PHN polymer} ^0.85 Example 3: Absorbance spectra of bismuth oxycarbonate composite materials and combination products UV-visible spectrophotometric absorbance spectra of the composite materials in accordance with the invention and prepared according to Example 2 were produced. They were obtained by UV-visible spectrophotometry on dispersions at 0.005% by mass of composite in water or in a water/propylene glycol/polysorbate 20 (Tween 20) mixture of respective mass fractions 49.85/49.85/0.30 for composite materials R, S1, S2 and T and AA, HH, II and JJ. The quartz cell used for the absorbance measurements has a side length of 1 cm. The spectrophotometer used is the Genesys 10S from Thermo Fischer Scientific. Preparation of the dispersions The aqueous dispersions of bismuth oxycarbonate/polymer composite materials containing 0.1% by mass of bismuth oxycarbonate are exposed to ultrasound for 2 to 15 minutes then stirred with a magnetic stirrer for 16 h. The suspensions are then diluted to 0.005% by mass of bismuth oxycarbonate and stirred again using a magnetic stirrer for 20 min in order to perform the absorbance measurement. Beyond a predetermined threshold UV absorbance measurement value, the filtering of the UV radiation is considered to be effective. In particular, composite materials with a UV absorbance threshold, in the dispersion medium comprising said composite materials at a mass fraction of 0.005%, of greater than 0.25 are considered effective for filtering UV radiation. The absorbance spectra are shown in Figures 1 to 20. The results are collated in Table 2 below. [Table 2] Composite Composite Composite Composite Composite Composite Absorbance A1 A2 B1 B2 C1 C2 Absorbance 0.8 0.38 0.48 0.5 0.84 0.56 at 220 nm Absorbance 0.96 0.42 0.5 0.58 0.98 0.68 at 300 nm Absorbance 0.48 0.24 0.34 0.36 0.68 0.46 at 400 nm Absorbance 0.12 0.1 0.16 0.12 0.24 0.16 at 620 nm Composite Composite Composite Composite Composite Composite Absorbance C3 C4 D E1 E2 F1 Absorbance 0.72 0.68 0.68 0.5 0.52 0.59 at 220 nm Absorbance 0.84 0.8 0.8 0.56 0.64 0.68 at 300 nm Absorbance 0.56 0.52 0.42 0.36 0.44 0.42 at 400 nm Absorbance 0.18 0.18 0.12 0.16 0.16 0.18 at 620 nm Composite Composite Composite Composite Composite Composite Absorbance F2 G H1 H2 I J1 Absorbance 0.84 2.7 2.5 1.7 2.65 2.6 at 220 nm Absorbance 0.98 1.2 1 1.15 1.35 1.35 at 300 nm Absorbance 0.56 0.5 0.5 0.45 0.45 0.5 at 400 nm Absorbance 0.22 0.1 0.2 0.1 0.08 0.12 at 620 nm Composite Composite Composite Composite Composite Composite Absorbance J2 K L1 L2 M N1 Absorbance 1.55 0.74 0.72 0.66 0.48 0.52 at 220 nm Absorbance 1.1 0.8 0.78 0.72 0.52 0.6 at 300 nm Absorbance 0.5 0.32 0.32 0.32 0.32 0.36 at 400 nm Absorbance 0.12 0.08 0.08 0.08 0.12 0.12 at 620 nm Composite Composite Composite Composite Composite Composite Absorbance N2 O1 O2 P1 P2 Q1 Absorbance 0.48 0.84 1.14 1.04 0.46 0.72 at 220 nm Absorbance 0.48 0.96 1.36 1.16 0.52 0.86 at 300 nm Absorbance 0.28 0.52 0.78 0.44 0.28 0.48 at 400 nm Absorbance 0.12 0.2 0.3 0.08 0.12 0.16 at 620 nm Composite Composite Composite Composite Composite Composite Absorbance Q2 R S1 S2 T U Absorbance 0.64 0.72 0.76 0.72 0.4 0.1 at 220 nm Absorbance 0.74 0.84 0.9 0.84 0.46 0.11 at 300 nm Absorbance 0.4 0.32 0.36 0.36 0.38 0.1 at 400 nm Absorbance 0.16 0.08 0.08 0 0.2 0.08 at 620 nm Absorbance Bismuth Composite Composite Composite Composite Composite Alfa Aesar V W X Y Z Absorbance 0.01 0.40 0.35 0.50 0.62 0.32 at 220 nm Absorbance 0 0.46 0.40 0.60 0.70 0.40 at 300 nm Absorbance 0.03 0.38 0.34 0.48 0.40 0.28 at 400 nm Absorbance 0.04 0.18 0.16 0.22 0.10 0.10 at 620 nm Composite Composite Composite Composite Composite Absorbance AA DD HH II JJ Absorbance 1.34 1.40 1.35 0.81 0.80 at 220 nm Absorbance 1.64 1.80 1.65 1.01 0.97 at 300 nm Absorbance 1.05 0.58 0.93 0.69 0.89 at 400 nm Absorbance 0.40 0.16 0.25 0.21 0.42 at 620 nm The composite materials in accordance with the invention show good absorbance of UV rays and consequently efficient screening of UV rays, and notably the UV-B range. In contrast, the comparative composite materials show low absorbance, and do not afford sufficient screening of the entire UV range. The absorbance spectra also show that the composite materials in accordance with the invention have high transparency in the visible range between 400 and 780 nm. Example 4: Kinetics of absorption of composite materials composed of particles of bismuth oxycarbonate and a polymer, and of the combination of bismuth oxycarbonate particles with this same polymer at the same mass ratio The kinetics of absorption of composite materials composed of particles of bismuth oxycarbonate and a polymer, and of the combination of bismuth oxycarbonate particles with this same polymer at the same mass ratio, is studied for t = 0 and t = 48 h at 45 °C, on dispersions containing 0.005% by mass of bismuth oxycarbonate in water. The absorbance spectra are obtained by UV-visible spectrophotometry according to the protocol described in Example 3, and are presented in Figures 16 and 17. The results are collated in Table 3 below. [Table 3] Product Composite I Composite I at t = Product EE at t = Sodium Absorbance at t = 0 48h and T = 45°C EE at t = 48 h and T = 45°C lignosulfonate 0 Absorbance 2.6 2.6 2.6 2.6 1.6 at 220 nm Absorbance 1.25 1.25 1.25 1.25 0.18 at 300 nm Absorbance 0.4 0.4 0.4 0.4 0 at 400 nm Absorbance 0.1 0.1 0.1 0.1 0 at 620 nm Composite D at t Composite Product Product FF at t = Absorbance = 48 h and T = D at t = 0 FF at t = 0 48 h and T = 45°C 45°C Absorbance 0.76 0.9 0.34 0.67 at 220 nm Absorbance 0.9 1.04 0.4 0.72 at 300 nm Absorbance 0.46 0.54 0.32 0.46 at 400 nm Absorbance 0.12 0.14 0.16 0.2 at 620 nm The composite materials in accordance with the invention show good absorbance of UV rays at t = 0 and t = 48 h, and at 45 °C, and consequently efficient screening of UV rays, and notably the UV-B range. In contrast, the comparative products do not afford sufficient screening of the entire UV range. Example 5: Preparation of aqueous composition A1.1 according to the invention A solution of sodium lauryl ether sulfate (Rhodapex ESB 30HA1 MB, commercialized by Solvay) is prepared at a concentration of 1% by weight in water, by stirring until complete solubilization. It is then diluted in water to reach the concentration 0.1% by weight. The composite material A1, synthesized according to Example 2.A1, is then added at the concentration of 0.1 % by weight to the diluted solution of sodium lauryl ether sulfate. The mixture is homogenized by magnetic stirring at 600 rpm for 5 minutes, then sonicated in an ultrasonic bath (Prolabo TP 680/DH) at power 100 % in continuous mode for 15 minutes. It is finally placed under magnetic stirring at 600 rpm for 16 hours. The composition obtained as a dispersion is referred to as A1.1. Example 6: Absorbance spectrum of aqueous composition A1.1 according to the invention Dispersion A1.1 according to Example 5 is diluted by addition of deionized water to reach the final concentration in composite material A1 of 0.005 % by weight, then placed under magnetic stirring at 600 rpm for 20 minutes before running the absorbance measurement. The quartz cell used for absorbance measurements is 1 cm thick. The absorbance spectrum is acquired using a UV-2600 UV-Vis Spectrophotometer (Shimadzu). The baseline determination is previously performed on a quartz cell filled with water. Above a predetermined threshold value of the measured UV absorbance, filtration of UV rays is considered to be efficient. Particularly, the compositions containing 0.005 % by weight of composite material A1 according to Example 2.A1 are considered to efficiently filter UV rays if their maximum of absorbance in the UV range is higher than 0.25. The absorbance spectrum of composition A1.1 according to the invention is given in Figure 21. The results of absorbance values are reported in Table 4 below. [Table 4] Absorbance Composition A1 Absorbance at 220 nm 0.63 Absorbance at 300 nm 0.74 Absorbance at 400 nm 0.34 Absorbance at 620 nm 0.08 The composition A1.1 according to the invention shows good absorbance of UV rays and consequently efficient filtration of UV rays, particularly in the UVB range. The absorbance spectrum also shows that composition A1.1 according to the invention has a high transparency in the visible range between 400 and 780 nm.

Claims

Claims 1. Composite material comprising: a) at least one particle of bismuth oxycarbonate of formula (I) (BiO)_2-x(CO₃), and solvates thereof, such as hydrates thereof, in which -0.4 < x < 0.6, the largest mean dimension of said particles being less than 400 nm; and b) at least one polymer. 2. Composite material according to Claim 1, characterized in that it has a mean size of the largest particle dimension of the composite material of less than or equal to 1 µm, and more preferentially less than or equal to 500 nm, even more preferentially less than or equal to 450 nm. 3. Composite material according to either one of the preceding claims, the mass ratio of bismuth oxycarbonate particle(s) a) to polymer(s) b) ranging from 0.01 to 50, preferably from 0.2 to 15, more preferentially from 0.3 to 10, and more preferentially from 0.5 to 8.5. 4. Composite material according to any one of the preceding claims, comprising: - a core comprising at least a) at least one particle of bismuth oxycarbonate of formula (I) (BiO)_2-x(CO₃), and solvates thereof, such as hydrates thereof, in which -0.4 < x < 0.6, the largest mean dimension of said particles being less than 400 nm; and - at least one layer continuously or discontinuously surrounding said core and comprising b) at least one polymer. 5. Composite material according to the preceding claim, the molar ratio between the number of moles of coating compound(s) and the number of moles of core compound(s) ranging from 0.0001 to 20, preferably ranging from 0.005 to 15, more preferentially ranging from 0.01 to 10, and even more preferentially ranging from 0.05 to 5. 6. Composite material according to any one of the preceding claims, said bismuth oxycarbonate particles being crystalline. 7. Composite material according to any one of the preceding claims, said bismuth oxycarbonate particles being of formula (BiO)₂(CO₃), and solvates thereof, such as hydrates thereof. 8. Composite material according to any one of the preceding claims, said bismuth oxycarbonate particles being in the form of tubes, platelets and/or rods, preferably in the form of platelets and/or rods. 9. Composite material according to any one of the preceding claims, said polymer(s) b) being nonionic, anionic or cationic, preferentially nonionic or anionic, more particularly being chosen from polyethylene glycols, polyethylene amines, polypropylene glycols, polyvinyl alcohols, polyacrylic acids and salts thereof, polymethacrylic acids and salts thereof, polymethyl methacrylates, polyvinyl sulfonates, polystyrene sulfonates, polylactic acids and salts thereof, polycaprolactones, polyglycolic acids, polyacetoacetates, poly(lactic-co-glycolic) acids, celluloses and derivatives thereof, alginic acids and salts thereof, carrageenans, starches, pectins, inulins, dextrans and derivatives thereof, xanthan gum, ulvans, lignosulfonates and salts thereof, chitins and chitosans, pullulans, polyvinyl alcohols and polyhydroxystearic acid, and/or copolymers thereof, or mixtures thereof. 10. Composite material according to any one of the preceding claims, said polymer(s) b) being chosen from: - lignosulfonic acid, lignosulfonates, sulfonic polystyrenes, polystyrene sulfonates, anionic polyanethole derivatives, in particular polyanethole sulfonates, and mixtures thereof, - alkyl esters or ethers of polyols, in particular of glycerol, - anionic polysaccharides, preferably chosen from sulfated polysaccharides, in particular ulvans, dextran sulfates, carrageenans and mixtures thereof, and polysaccharide carboxylates, in particular alginates, - cationic polysaccharides, preferably chosen from polysaccharides bearing amine groups, in particular chitosans, - modified polysaccharides, in particular chosen from polysaccharide esters and preferably from pullulan esters, - poly((C2-C5)alkyleneimines), and preferably from polyethyleneimines and polypropyleneimines, notably poly(ethyleneimines), - polyamino acids, and preferably from proteins, - anionic acyclic polymers bearing carboxyl groups or carboxylates of alkali metals or alkaline-earth metals, such as sodium, and chosen from homo- or copolymers of (meth)acrylic acid, preferably from sodium polymethacrylates and copolymers of (meth)acrylic acid with alkyl (poly)ether (meth)acrylates, in particular copolymers of (meth)acrylic acid and POE/POP (meth)acrylate, and - - mixtures thereof. 11. Composite material according to any one of the preceding claims, said polymer(s) b) being chosen from: - lignosulfonates, notably of alkali metals or alkaline-earth metals, such as sodium or calcium lignosulfonates, - carrageenans, - chitosans, - alginates, notably of alkali metals or alkaline-earth metals, such as sodium alginate, - dextrans, in particular of alkali metals or alkaline-earth metals, and dextran sulfates of alkali metals or alkaline-earth metals, such as sodium dextran sulfate, - polyhydroxystearic acids, - starches and derivatives thereof, notably phosphated derivatives thereof, such as hydroxypropyl corn distarch phosphate, - pullulans and ester derivatives thereof, notably of C1-C30, preferably C10-C20 carboxylic acid, such as myristoyl pullulan, - polyvinyl alcohols, - optionally hydrolyzed proteins, such as optionally hydrolyzed soy proteins, and - mixtures thereof. 12. Composite material according to any one of claims 1 to 9, said polymer(s) b) being chosen from polysaccharides, in particular: - anionic polysaccharides, preferably chosen from sulfated polysaccharides, in particular ulvans, dextran sulfates, carrageenans and mixtures thereof, and polysaccharide carboxylates, in particular alginates, - cationic polysaccharides, preferably chosen from polysaccharides bearing amine groups, in particular chitosans, - modified polysaccharides, in particular chosen from polysaccharide esters and preferably from pullulan esters. 13. Process for preparing a composite material according to any one of the preceding claims, comprising at least the steps of: (i) providing at least one particle of bismuth oxycarbonate a) of formula (I) (BiO)_2-x(CO₃), formula (I), and solvates thereof, such as hydrates thereof, in which -0.4 < x < 0.6, the largest mean dimension of said particles being less than 400 nm, optionally dispersed in at least one solvent or mixture of solvents A; (ii) providing a solution of at least one polymer b), optionally in a solvent or mixture of solvents B; (iii) bringing said at least one particle a) or dispersion (i) and said solution (ii) in contact to form the composite material; (iv) isolating said composite material. 14. Preparation process according to the preceding claim, said solvent(s) A and/or B being chosen from apolar aprotic solvents, polar protic solvents, more preferentially from water, alcohols, polyols, and mixtures thereof. 15. Preparation process according to either one of Claims 13 and 14, also comprising one or more steps of separation, in particular by centrifugation and/or by filtration, in particular ultrafiltration, and/or by lyophilization and/or by atomization. 16. Composition, notably cosmetic composition, comprising at least one composite material according to any one of Claims 1 to 12. 17. Composition according to the preceding claim, comprising at least: i) at least one composite material according to any one of Claims 1 to 12; ii) at least one aqueous phase and/or at least one fatty phase; and iii) at least one compound chosen from: 1) UV-screening agents different from the composite materials i); 2) colorants; 3) cosmetic active agents for caring for keratin materials; 4) surfactants; 5) thickeners; and mixtures thereof. 18. Composition according to either one of Claims 16 and 17, said composite materials being present in a content ranging from 0.5% to 70% by weight, preferably from 1% to 50% by weight and better still from 2% to 40% by weight, relative to the total weight of the composition. 19. Non-therapeutic cosmetic use of a composite material according to any one of Claims 1 to 12, for filtering UV radiation, preferably UV-B radiation, comprising at least the application to keratin materials of a composition comprising a composite material according to any one of Claims 1 to 12. 20. Non-therapeutic cosmetic process for filtering UV radiation, preferably UV-B radiation, comprising at least the application to keratin materials of a composition comprising a composite material according to any one of Claims 1 to 12.