EP4247538A1 - Method for preparing biodegradable microcapsules and use of the resulting microcapsules - Google Patents

Abstract

Use of biodegradable microcapsules comprising a wall made of poly(beta-amino)ester, abbreviated to PBAE, which contains an active substance. These microcapsules may be obtained by a method of interfacial polymerization between an amine monomer and a multi-acrylate monomer. Depending on the intended use, microcapsules with a wall that is weak, breakable or unbreakable and porous or non-porous are used; these properties may be obtained by the choice of the monomers and the thickness of the wall. For certain uses, it is possible to use the polymerization reaction mixture directly, without washing.

Description

METHOD FOR THE PREPARATION OF BIODEGRADABLE MICROCAPSULES AND USE OF THE MICROCAPSULES THUS OBTAINED

Technical field of the invention

The present invention relates to the field of microcapsules, and more particularly to processes for manufacturing microcapsules with a view to enclosing active substances such as essential oils. More specifically, it relates to a method for preparing biodegradable microcapsules. This method proceeds by interfacial polymerization of multifunctional compounds leading to poly(beta-amino ester)s forming the wall of these microcapsules. The invention also relates to the biodegradable microcapsules obtained by this method.

The present invention also relates to the use of the microcapsules obtained by the method according to the invention, depending on the mechanical and physicochemical properties of their wall.

State of the art

Micro-encapsulation is a process for protecting a reactive, sensitive or volatile substance (here called “active principle”) in a capsule whose size can vary from nanometer to micrometer. The core of the capsule is therefore isolated from its external environment by a wall. This makes it possible to delay its evaporation, its release or its deterioration; there are many applications that exploit these technical effects when the microcapsules are incorporated into a complex formulation or applied to a product.

By way of example, the microcapsules can be used to spread in a controlled manner the active principle that they contain, which can in particular be a biocidal active ingredient, an insecticide, a disinfectant, or a fragrance; this can be done by diffusion through the wall or under the influence of an external force which breaks the wall. In certain applications, the release of the active principle takes place under the influence of an external force which breaks the wall of the microcapsules; thus, an adhesive can be released (see for example WO 03/016369 - Henkel), or a reagent (see for example WO 2009/115671 - Catalysis).

In other applications, the contents of the microcapsule cannot escape but its color change under the effect of a variation in temperature (thermochromy) or UV irradiation (photochromy) is visible from the outside ( see for example WO 2013/114 025 - Gem Innov, or WO 2007/070118 - Kimberly-Clark, or EP 1 084 860 - The Pilot Ink Co.). There are several techniques for preparing microcapsules. The main ones are atomization (in English: "spray-drying"), interfacial polymerization, solvent evaporation, self-assembly of polymers by the Layer by Layer (LbL) technique and the preparation of colloidosomes. All these techniques make it possible to obtain stable microcapsules with an average diameter of 10 μm. Interfacial polymerization is nevertheless the predominant technique because it allows the rapid preparation and in a single step of microcapsules whose wall is strong enough for them to be isolated and thus be used in many applications.

The formation of microcapsules by interfacial polymerization is usually done in 4 steps: (i) Preparation of a first phase containing the active principle (for example an essential oil) and an organosoluble monomer; (ii) Formation of an emulsion by dispersion of the first phase in an aqueous medium containing the surfactant, and which represents the second phase; (iii) Addition of the water-soluble monomer in the second phase; (iv) Formation and maturation of the membrane by reaction of monomers by polycondensation at the interface.

Several polymer families are conventionally used to manufacture the wall of microcapsules (Perignon, C. et al., Journal of Microencapsulation 2015, 32 (1), 1-15), such as polyamides (PA), polyurethanes (PU) or polyureas. The production of the walls of the microcapsules in PA generally uses monomers of the diamine type (hexamethylene diamine for example) and acyl chloride (sebacoyl chloride for example), while those in PU use monomers of the diamine type. -isocyanate (HDI, IPDI etc.) and diols. In the case of polyureas, monomers of the diisocyanate and diamine type or diisocyanates alone are used, the hydrolysis of which at the interface produces the amines allowing the synthesis of the urea function.

By way of example, the aforementioned document WO 2009/115671 describes the formation of microcapsule walls by interfacial polycondensation, from different mixtures of monomers: hexamethylene diisocyanate (HMDI) and ethylene diamine; tetraethyl-orthosilicate (TEO) and 3-(trimethoxysilyl)propylmethacrylate (MPTS); 2,4-tolylene diisocyanate (TDI) and 1,3 phenylenediamine; 2,4-toluene diisocyanate and 1,3-phenylene diamine.

There are already some works reporting the preparation of microcapsules by interfacial polymerization using other types of polymers. We can quote by example, the work of J. Bernard on the preparation of glyconanocapsules by azide-alkyne cycloaddition catalyzed by copper (R. Roux et al., J. ACS Macro Lett. 2012, 1 (8), 1074-1078), or the work of K. Landfester (Siebert et al. Chem. Commun. 2012, 48, 5470-5472). L.Shi et al. (J. Appl. Polym. Sci. 2016, 133 (36), 168-7) as well as D. Patton et al. (ACS Appl. Mater. Interfaces 2017, 9 (4), 3288-3293) who were also able to prepare microcapsules by thiol-ene chemistry primed with a base and a photoinitiator respectively.

A fairly broad spectrum of polymeric materials is therefore available to those skilled in the art to select the type of microcapsule appropriate for a given use. Thus, microcapsules are already used in many technical applications, but their application potential has not yet been fully recognized, and it is a highly emerging sector set to grow significantly from the moment the microcapsule wall meets increasingly stringent criteria in terms of toxicity and recyclability.

However, microcapsules represent micro parts of polymeric materials. In recent years, microparticles of polymeric materials have been identified as an area of ecological concern, because of their wide dissemination in ecosystems, in soils, in aquatic and maritime ecosystems, to places far from their place of origin. introduction into the ecosystem. This wide spread not only generally harms the organisms present in these ecosystems, but could also have adverse consequences for human health. We are already seeing the announcement of increasingly strict regulations which restrict the use of plastic materials liable to form microparticles during their degradation in a situation in a natural environment, and a fortiori plastic materials used from the outset in the form of microparticles .

For ecological reasons, it may seem contradictory to seek to develop a new product consisting of polymeric microparticles. It therefore appeared desirable to have microcapsules made of degradable polymeric material. It should be noted that the microcapsules, used in numerous special applications and capable of being incorporated into numerous products in common use (such as textiles, cosmetic or phytosanitary products) or for technical use (such as paints, varnishes, inks), will not normally be collected at the end of their life, and therefore cannot be subject to biodegradation by composting, such as can be considered for collected plastic products. Thus, the degradability of the plastic materials which constitute the wall of the microcapsules cannot be based on the chemical mechanisms which take place during composting. In this context, the question of whether the degradability of the microcapsules involves a biological mechanism is relatively unimportant; what matters is their degradability in an ecosystem, regardless of the chemical mechanism of this degradation. For example, a fermentation would be a biodegradation, while a simple degradation in an ecosystem under the effect of light could be a photochemical reaction independent of the ecosystem; in reality the situation will often be mixed, especially if degradation proceeds in stages. In what follows, we use the expression "(bio)degradable" to designate the characteristic of a material to degrade in a natural environment on a fairly short scale (of the order of weeks or a year), in depending on the characteristics of this natural environment and the exposure of the material to the various agents present in this natural environment.

It can be seen that all the microcapsules developed previously lead to the preparation of polymer chains (polyamide, polyurea, polyurethane, etc.) which will be either physically entangled in the case of a reaction between bifunctional compounds, or cross-linked in the case of one or more multifunctional compounds (functionality > 3). In all cases, the walls are not (bio)degradable due to the nature of the polymer chain.

The problem that the present invention seeks to solve is to present a new type of microcapsule, easy to synthesize, without using toxic and/or expensive raw materials, which is (bio)degradable in the natural environment, which can be used with a large number of active ingredients, and which provides good external protection to the active ingredient that it is intended to contain. This new type of microcapsule allows a wide variety of new uses.

Objects of the invention

During their research work, the inventors found that one possibility for obtaining degradable microcapsules would be to prepare walls of polyester, which is a polymer known for its (bio)degradability. The literature shows that studies have already been conducted on this topic, and it has been shown that the reaction rate between acid chlorides and diols was very slow. This system is thus poorly suited to interfacial polymerization (see EM Hodnett and DA Holmer, J Polym Sci, 1962, 58, 1415-21). Special conditions such as the use of bisphenol A as diol and/or a very high pH reaction made it possible to obtain microcapsules (see W. Eareckson, J Polym Sci, 1959, 399-406; see also PW Morgan and SL Kwolek, J Polym Sci, 1959, 299-327) but these conditions are too restrictive for many internal phases and/or applications. In addition, the slowness of the polymerization reactions harms their industrial use in economic terms and short or even continuous production cycles.

Thus, the inventors did not pursue this path.

According to the invention, the problem is solved by using microcapsules made of poly(beta-amino)ester (abbreviated here as PBAE). According to the invention, these microcapsules are synthesized in a single reaction step by an addition reaction of the amine functions on the acrylate functions (reaction known as the “Michael addition”), by interfacial polymerization. This reaction leads to the micro-encapsulation of the organic phase without the formation of by-products (see the reaction scheme in Figure 6). The presence of ester functions in the backbone of the PBAE gives the polymer good degradation properties by hydrolysis.

Poly(beta-amino esters) are known as such and have been widely used in recent years (Lynn, D. M.; Langer, R. J. Am. Chem. Soc. 2000, 122 (44), 10761-10768.; Liu , Y.; Li, Y.; Keskin, D.; Shi, L. Adv. Healthcare Mater. 2018, 2 (2), 1801359-24) thanks to their biocompatibility and biodegradability properties, and today they represent a family of materials which has numerous applications as biomaterials (for example as a vector of anticancer molecules, as an antimicrobial material, and for tissue engineering).

The fields of application of poly(beta-amino ester)s are very broad (see figure 9).

In general, it is known that aza-Michael addition type reactions can be carried out in a wide range of solvents ranging from halogenated apolar solvents (dichloromethane or chloroform for example) to polar solvents such as dimethylsulfoxide (DMSO) for example ( Liu, Y.; Li, Y.; Keskin, D.; Shi, L. Adv. Healthcare Mater. 2018, 2(2), 1801359-24). In practice, PBAEs are essentially prepared in solution and are then formulated to produce, for example, micelles, particles, gel/hydrogels, or films (so-called Layer by Layer technique). Oligo-PBAEs were also crosslinked in a second step either by photopolymerization (Brey, DM; Erickson, I.; Burdick, JAJ Biomed. Mater. Res. 2008, 85A (3), 731-741.7), or in the presence of diisocyanates.

It is also known that linear or cross-linked PBAEs are relatively stable in a neutral medium but degrade more rapidly by hydrolysis of the ester functions at acidic and/or basic pH. This phenomenon of hydrolysis leads to the release of small molecules such as bis(P-amino acid)s and diols when linear PBAEs are used; these molecules are known to be non-toxic with respect to mammalian cells, and of little influence on the metabolism of healthy cells.

According to an essential characteristic of the present invention, the microcapsules having a PBAE wall are synthesized by interfacial polymerization.

More specifically, according to the invention, the problem is solved by a process in which the Michael polycondensation reaction is used between amine functions and acrylate functions to obtain Poly(Beta-Amino Esters) (PBAE) by interfacial polymerization. The inventors have found that this process, applicable to various active ingredients to be encapsulated, makes it possible to prepare stable microcapsules which can be isolated by drying and which have the property of being (bio)degradable.

The micro-encapsulation process according to the invention comprises the following steps:

(a) Dispersion of one or more compounds having at least two acrylate functions in an organic solution (also called "oily phase" here, in the context of an emulsion) constituting the phase to be encapsulated (and comprising, where appropriate , the active ingredient);

(b) Addition of an excess relative to the previous volume of an aqueous phase comprising one or more surfactants, followed by emulsification;

(c) Addition to the emulsion obtained in step (b) of one or more compounds comprising at least one primary amine function and/or two secondary amine functions and polymerization reaction at a temperature between approximately 20°C and 100°C; to obtain microcapsules comprising a PBAE wall containing the phase to be encapsulated.

Depending on the intended use, this reaction mixture, referred to here as “primary reaction mixture”, can be used as it is, optionally after having diluted it with an appropriate liquid phase, or the microcapsules can be collected, washed and/or dried. The new process for manufacturing microcapsules containing a so-called active substance can therefore be described as follows: an aqueous solution of a surfactant is supplied, an oily phase comprising said active substance and at least a first monomer X, and a phase polar comprising at least one second monomer Y; an emulsion of O/W type is prepared by adding said oily phase to said aqueous solution of the surfactant; said polar phase is added to said O/W emulsion, to enable a polymer to be obtained by polymerization of said monomers X and Y; said process being characterized in that said polymer is a poly(beta-amino ester).

In an optional step, said microcapsules comprising a wall formed by said polymer and containing said active substance are isolated from this reaction mixture.

It is also possible, before or after this optional step, to modify the external surface of the wall of the microcapsules by a physical coating or by a chemical reaction.

Said first monomer X is selected from (multi)acrylates, in particular (multi)acrylates of formula X'-(-O(C=O)-CH=CH2)n with n > 2 and where X' represents a molecule on which is grafted with n acrylate units.

Said first monomer X is preferably selected from (multi)acrylates of formula X'-(-O(C=O)-CH=CH2)n with n > 4 and where X' represents a molecule on which is grafted n acrylate patterns. More specifically, it is advantageously selected from the group formed by: diacrylates, and preferably those described in the article by Nayak et al. (Polymer-Plastics Technology and Engineering, 2018, 57, 7, 625-656); triacrylates, in particular C15O6H20 (CAS No. 15625-89-5, ie trimethylolpropane triacrylate), tetraacrylates, pentaacrylates, hexaacrylates, mixtures between these different acrylates of the O[CH2C(CH2OR)s]2 type where R is H or COCH=CH ₂ ; the (multi)acrylates described in the article by Nayak et al. (Polymer-Plastics Technology and Engineering, 2018, 57, 7, 625-656); polymers carrying pendant acrylate functions; functional oligo PBAEs, prepared for example by reacting diacrylate compounds with a functional primary amine and/or a functional secondary diamine; the mixture of different compounds described above.

Said second monomer Y is selected from amines. More specifically, it is advantageously selected from the group formed by: primary amines R—NH2; primary diamines of the NH2(CH2) _n NH2 type where n is an integer which can typically be between 1 and 20, and which is preferably 2 or 6; primary diamines comprising an aromatic core such as meta-xylylene diamine; primary (multi)amines such as tris(2-aminoethyl)amine; secondary diamines such as piperazine; (multi)amines containing primary and secondary amine functions such as tetraethylene pentamine; polymers containing primary and/or secondary amine functions such as polyethylene imine.

In one embodiment, said polymerization of said monomers takes place with stirring at a temperature of between 20°C and 100°C, and preferably between 30°C and 90°C.

The microcapsule containing a so-called active substance, which can be manufactured by this process, is characterized in that its wall is formed of poly(beta-amino ester). This wall can be modified by adding a layer of polymer deposited on the surface of the microcapsules. This deposition can be done by adding a polymer dispersed in an aqueous phase which will be deposited on the surface of the capsules. Among these polymers, mention may be made of polysaccharides (for example cellulose, starch, alginates, chitosan) and their derivatives.

Another possibility for modifying the wall of the microcapsules is to modify it by adding a radical initiator either in the aqueous phase or in the oily phase. A last possibility is to react the residual amine functions on the surface with water-soluble monofunctional acrylates to modify the surface state of the microcapsules.

A first object of the present invention is the use of microcapsules with a biodegradable wall made of Poly(Beta-Amino Ester), abbreviated PBAE, containing at least one active substance, in the formulation of products selected from the group formed by: Cosmetic products and care products intended to be applied to the face or body, in particular body creams and lotions, face creams and lotions, shower gels, bath gels, products with UV filters , self-adaptive make-up products correcting their shade according to ambient solar or electric lighting, said at least one microencapsulated active substance being in particular intended to be released in a controlled and targeted manner, in particular for vectorization in the skin, for stabilizing pigments and/or dyes, for covering wrinkles. Hair and scalp care products, including shampoos, conditioners, hair dyes. Depilatory waxes, said at least one microencapsulated active substance being preferably selected from the group formed by thermochromic substances and agents for temperature control. Disinfectant and/or deodorant products intended to be applied to the face or body, or to objects in contact with the body, to control or limit or mask body odor or to control or limit or mask body odor objects in contact with the body, said at least one active substance being preferably selected from the group formed by antiperspirants, perfumes, essential oils, fragrances, oils. Cosmetic textiles, intended to come into contact with the skin, said at least one active substance preferably being selected from the group formed by antioxidant products, anti-cellulite products, products capable of stimulating blood circulation, anti-mold products , antimicrobial products, bactericidal products, virucidal products, oils, colorants, UV screens, surfactants, vitamins, moisturizing agents, skin penetration enhancers, exfoliating agents, emollients, anti-wrinkle agents, depigmentation agents, humectants; knowing that this group of products can also apply to any other product for cosmetic use and to any composition for cosmetic use. Medical textiles, such as dressings, intended to come into contact with the skin or with wounds, said active substance being a pharmaceutical active principle. Pharmaceutical preparations, in particular intended for use orally, nasally, intra-bloodally, rectally or by topical application, for example cutaneous or ocular, said at least one active substance preferably being selected from the principles pharmaceutical actives. Preparations for the care of the teeth and the mouth, said at least one active substance being preferably selected from bactericidal products, enzymes, flavorings, essential oils, sweeteners. Food preparations, said at least one active substance being preferably selected from flavorings, flavor enhancers, vitamins and vitamin preparations, preservatives, nutritional additives, oils. Insecticidal and/or fungicidal and/or repellent and/or anti-moss preparations, intended for use alone or incorporated into products such as phytosanitary products, paints, coatings, textiles, detergents, plastics. Preparations intended for use in the field of agriculture, said at least one active substance preferably being selected from additives for the cultivation of plants and fertilizers. Preparations intended for veterinary, intracorporeal or extracorporeal use, and in particular pharmaceutical preparations, dermatological preparations and coat care preparations, said at least one active substance being preferably selected from pharmaceutical active principles and in particular dewormers and antiparasitics, food additives, perfumes, fragrances. Preparations for the treatment of textile products, textile fibers or footwear, said at least one active substance preferably being selected from biocidal products, repellents, moth repellents, deodorizing products, self-cleaning products, stain-resistant products, antistatic products, self-healing products, self-repairing products, perfumes, fragrances, detergents, softeners. Preparations for the treatment of bedding, in particular mattresses, pillows, sheets, undersheets, luggage, fabrics and household equipment such as curtains, cushions, furniture, leather objects, said at least one active substance being preference selected from among biocidal products, repellents, moth repellents, anti-mite products, anti-lice products, anti-mosquito products, deodorant products, self-cleaning products, antistatic products, self-healing products, self-repairing products, perfumes, fragrances, detergents, softeners. Preparations for waterproof or water-repellent coatings, intended to be applied in particular to textile surfaces or leather surfaces, said at least one active substance preferably being selected from hydrophobic compounds, in particular fatty compounds or fluorinated compounds. Deodorant and/or disinfectant and/or antifoam and/or antifungal preparations, said at least one active substance preferably being selected from oily, natural or synthetic products. Detergent products. Preparations for coating building materials, preparations for ensuring watertightness and preparations for thermal insulation or for absorbing and restoring thermal energy, said at least one active substance preferably being selected from phase, paints and varnishes, thermal insulation materials, sealing agents, expansion agents. Products for treating floor coverings, said at least one active substance being preferably selected from the group formed by lubricant products, anti-friction products, anti-slip products, detergents, essential oils, fragrances, perfumes, aromas. Paints, varnishes, dyes and inks, in particular inks for transfer printing, screen printing, ink jet printing or electrostatic printing, and preparations for coating or making paper, said at least one active substance preferably being selected from the group formed by dyes, pigments, thermochromic products, perfumes, aromas, fragrances. Self-repairing compositions intended in particular for use in surface coatings used in paint, varnish, inks, on cement, concrete, wood, and in compositions of polymer materials and composites. Compositions with a fire retardant and fire extinguisher effect, said at least one active substance possibly being chosen in particular from brominated alkanes of general formula C _n H2n+2-xBr _x ..

Said microcapsules which form the basis of this new use are likely to be obtained by a process in which:

(a) an aqueous solution of a surfactant, an oily phase comprising said active substance and at least one first monomer X, and a polar phase comprising at least one second monomer Y;

(b) an emulsion of the O/W type is prepared by adding said oily phase to said aqueous solution of the surfactant; (c) said polar phase is added to said O/W emulsion, to enable a polymer to be obtained by polymerization of said X and Y monomers, said polymer forming the wall of said microcapsules; and in which said first monomer X is preferably selected from (multi)acrylates, and preferably (multi)acrylates of formula X'-(-O(C=O)-CH=CH2)n with n > 4 and where X' represents a molecule on which n acrylate units are grafted, or selected from the group formed by: diacrylates; triacrylates, in particular trimethylolpropane triacrylate, tetraacrylates, pentaacrylates, hexaacrylates, mixtures of these different acrylates of the O[CH ₂ C(CH ₂ OR) ₃ ]2 type where R is H or COCH=CH ₂ ; polymers bearing pendant acrylate functions; functional oligo PBAEs, prepared for example by reacting diacrylate compounds with a functional primary amine and/or a functional secondary diamine; the mixture of different compounds described above.

In one embodiment, said second monomer Y is selected from amines and preferably selected from the group formed by: primary amines R—NH ₂ ; primary diamines of the NH ₂ (CH ₂ ) _n NH ₂ type where n is an integer which can typically be between 1 and 20, and which is preferably 2 or 6; primary diamines having an aromatic core, and preferably meta-xylylene diamine; (multi)primary amines, and preferably tris(2-aminoethyl)amine; (multi)amines containing primary and secondary amine functions, and preferably tetraethylene pentamine; secondary diamines and preferably piperazine; polymers containing primary and or secondary amine functions, and preferably polyethylene imine.

The ratio of the reactive functions of said monomers Y (-NH functions) and X (acrylate functions) is greater than 1, preferably between 1 and 5, and even more preferably between 1.2 and 3.8. Note that for an -NH ₂ group, two -NH functions are counted here. Said polymerization of said monomers takes place with stirring at a temperature of between 20°C and 100°C, and preferably between 30°C and 90°C.

The outer wall of the microcapsules can be modified by one of the following ways: Deposition of a coating on the surface of the microcapsule, preferably from a polymer dispersed in an aqueous phase, said polymer preferably being selected from polysaccharides , such as cellulose, starch, alginates, chitosan, and their derivatives.

- Addition of a radical initiator in the aqueous phase and/or the oily phase, said radical initiator preferably being selected:

When added to the aqueous phase: in the group formed by water-soluble azo compounds, such as 2,2'-Azobis(2-methylpropionamidine) dihydrochloride, and red-ox systems, such as ammonium persulfate or potassium in combination with potassium metabisulphite;

In the event of addition in the oily phase: in the group formed by azo compounds, such as azobis-isobutyronitrile and its derivatives, and peroxidic compounds, such as lauroyl peroxide;

- Addition in the aqueous phase of a water-soluble acrylate capable of modifying the surface state of the microcapsules, said acrylate preferably being a water-soluble monofunctional acrylate capable of reacting with the residual amine functions at the surface of the wall of the microcapsules, said water-soluble monofunctional acrylates being preferably selected from the group formed by 2-carboxyethyl acrylate, 2-(dimethylamino)ethyl acrylate, 2-hydroxyethyl acrylate, poly(ethylene glycol) acrylates, the potassium salt of 3-sulfopropyl acrylate.

More generally, it can also be modified so as to have an anionic or cationic character.

Said microcapsules are characterized by one of the following characteristics or combination of characteristics: an indentation force at break greater than 5,000 pN, preferably greater than 6,000 pN, and even more preferably greater than 7,000 pN; these microcapsules being referred to herein as “unbreakable”; an indentation force at break of less than 300 pN and preferably a Tg value of less than 33° C., and in this case this Tg value being preferably less than 32° C. and even more preferably less than 31° C.; preferably by a indentation force at break of less than 250 N and preferably by a Tg value of less than 32° C., and in this case this Tg value being preferably less than 31° C. and even more preferably less than 30° C.; and even more preferably by an indentation force at break of less than 200 pN and preferably by a Tg value of less than 32°C, and in this case this Tg value being preferably less than 31°C and even more preferably below 30°C; these microcapsules being referred to herein as “fragile”; an indentation force at break between 200 pN and 5,000 pN, and preferably between 300 pN and 5,000 pN, but with a breaking force between 200 pN and 300 pN their Tg value is preferably at least 33° C., and for the microcapsules with a breaking force greater than 300 pN, it is preferable that their Tg value be between 30° C., preferably between 33° C., and 80° C.; these microcapsules being referred to herein as “brittle”.

For some uses it is preferred to use fragile microcapsules, for others breakable microcapsules, for still others unbreakable microcapsules. Brittle or unbreakable microcapsules can be more or less porous (or permeable), depending on the nature of the monomers chosen and the thickness of the wall; this porosity or permeability can be exploited for some of the new uses which will be described below, and for others it must be avoided.

According to an embodiment which is advantageous for certain uses, the reaction mixture resulting from step (c) can be used directly, optionally after adjustment of the pH value (which can be useful in particular in the event of an excess of amine ). A slurry is thus used which can enter directly into liquid, viscous or pasty preparations, without having washed, isolated and/or dried the microcapsules beforehand. This simplifies the manufacturing process.

According to another embodiment which is advantageous for certain uses, the reaction mixture resulting from said reaction for modifying the external surface of the microcapsules can be used directly.

For still other uses it is preferable to use the microcapsules after washing and possibly drying. Such microcapsules with a purified surface are particularly suitable for uses in pharmacy and cosmetics.

A second object of the invention is a method of using microcapsules with a biodegradable wall made of Poly(Beta-Amino Ester), containing at least one substance active, in the formulation of products in the group listed above in relation to the first object of the invention. This method of use may include a step in which the microcapsules, preferably in a slurry form, are incorporated into a liquid, viscous or pasty preparation. This preparation can then be used as it is (for example in the form of an ink, a cosmetic or phytosanitary product) so as to allow the microcapsules to fulfill a desired technical function, and/or it can represent a vehicle for applying the microcapsules on another product, in particular on a solid product, for example on a textile fabric, to deploy there a desired technical function (for example a disinfectant effect for a textile).

A third object of the invention is a product capable of being obtained by the method of using microcapsules with a biodegradable wall made of Poly(Beta-Amino Ester), containing at least one active substance, said product being selected from the group listed above in relation to the first object of the invention.

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Figures 1 to 23 illustrate certain aspects of the invention, but do not limit their scope. Figures 2 to 5 relate to Example 1. Figure 7 relates to Example 2, Figure 8 to Example 3, Figure 8 to Example 3, Figure 10 to Example 6 , Figure 11 to Example 7, Figure 12 to Example 10, Figure 13 to Example 11, Figure 14 to Example 13, Figure 15 to Example 14, Figure 16 to example 15, figure 17 to example 17, figure 18 to example 18, figure 21 to example 26, figure 22 to example 27, and figure 23 to example 28 Figures 2 to 5 and 10 to 14 are optical micrographs; the horizontal bar at the bottom left of the image represents a length of 50 µm. Figures 17 and 18 are also optical micrographs. Figures 21 to 23 are thermogravimetric analysis (TGA) curves.

[Fig.1] shows the general diagram of the process according to the invention. The four-digit numerals designate steps in this process.

[Fig.2] shows an optical micrograph of microcapsules obtained according to example 1, after 5 hours of reaction.

[Fig.3] shows a Fourier transform infrared (FTIR) spectrum of the wall of the microcapsules isolated in the slurries after 6 hours of reaction.

[Fig.4] shows an optical micrograph of microcapsules obtained according to example 1, after drying on a glass slide. [Fig.5] shows two optical micrographs of microcapsules obtained according to Example 1, after drying on a glass slide. The micrograph on the left was obtained in grazing light, the micrograph on the right under fluorescent light after adding a few drops of a fluorescent dye.

[Fig.6] illustrates the reaction scheme of the reaction according to the invention.

[Fig.7] shows that the thermochromic microcapsules are stable after being put in the oven for 30 min and that their thermochromic function is preserved.

[Fig.8] illustrates the degradability of the walls of the microcapsule by an accelerated degradation test.

[Fig.9] illustrates the different fields of application of poly(beta-amino ester)s.

[Fig.10] shows that the microcapsules are stable after 24 h, and their average diameter is between 10 μm and 30 μm.

[Fig.11] shows an image similar to Figure 10, and leads to the same conclusion, for another example.

[Fig.12] shows the result of using the microcapsules according to the invention in carbonless paper.

[Fig.13] shows a photograph of microcapsules according to yet another example of the invention.

[Fig.14] shows a photograph of microcapsules according to yet another example of the invention.

[Fig.15] shows the percentage of biodegradation as a function of time for dry microcapsules according to the invention.

[Fig.16] shows the percentage of biodegradation as a function of time for the wall of the microcapsules according to the invention.

[Fig.17] shows a photograph of microcapsules according to yet another example of the invention.

[Fig.18] shows a photograph of a cotton fiber which has been brought into contact with microcapsules according to the invention, the surface of which has been modified (b) or not (a).

[Fig.19] shows the chemical formula of an amine carrying an anionic charge, which can be used as a monomer.

[Fig.20] shows the chemical formula of a polyacrylate, which can be used as a monomer.

[Fig. 21] shows the thermogravimetric analysis curves of three samples according to an example of the invention, namely unmodified microcapsules containing the active phase (curve (b)), microcapsules surface-modified with potzassium persulfate (curve ( c)), and of the active phase alone (essential oil of eucalyptus, curve (a)). [Fig. 22] shows curves similar to those of FIG. 21, curve (c) relating to microcapsules surface-modified by the initiator azobisisobutyronitrile.

[Fig. 23] shows curves similar to those of FIG. 22, curve (c) relating to microcapsules modified by photochemical polymerization.

detailed description

In the following detailed description of embodiments of this specification, numerous specific details are set forth in order to provide a more thorough understanding of the present invention, and to enable those skilled in the art to carry out the invention. . However, it will be apparent to those skilled in the art that the present description can be implemented without these specific details. In other cases, well-known characteristics have not been described in detail to avoid unnecessarily overloading the description.

Figure 1 shows a general diagram of the process according to the invention. The aqueous solution of the surfactant (1000) is prepared. An organic solution (also called “oily phase”) comprising the phase to be encapsulated (which comprises the so-called active substance) and the monomer X (1002) is also prepared. At step 1010, this oily phase 1002, which is an organic solution, is added to said aqueous solution 1000 and at step 1020 an emulsion 1022 of the O/W type (oil in water, in English Oil in Water) is obtained. , according to a designation known to those skilled in the art). In this emulsion, said organic solution is the so-called oily phase (O phase). In step 1030, an aqueous solution of monomer Y 1024 is added to said emulsion 1022. In step 1040, the polymerization reaction leads to a reaction mixture 1042 from which is then formed in step 1050 a heterogeneous mixture 1052 called slurry which comprises, in aqueous-based suspension, the microcapsules containing the phase to be encapsulated. It may contain a residue of unreacted monomers; this will be the case in particular if an excess of amine is used. This heterogeneous mixture (slurry) is called in the context of the present invention the “primary reaction mixture”. It can be used as it is, or be the subject of various operations of washing and/or collection and/or drying of the microcapsules contained in this heterogeneous mixture.

Step 1050 typically involves a temperature of reaction mixture 1042 above about 20°C, typically between 20°C and 100°C. A temperature between about 30°C and about 90°C is preferred, and even more preferably between about 40°C and about 80°C. This process can be applied to different monomers X and Y. According to the invention the monomer X is a (multi)acrylate, and the monomer Y is an amine, preferably a primary amine and/or a (multi)primary amine and /or a secondary diamine and/or a compound having primary and secondary amines.

By (multi)acrylate is meant any compound of formula X'-(-O(C=O)-CH=CH2)n with n>2 and where X' represents a molecule on which n acrylate units are grafted.

By primary (multi)amine is meant any compound comprising at least two primary amine functions.

As acrylate monomer (monomer X), it is possible to use, for example, triacrylates (such as C15O6H20, CAS No. 15625-89-5); tetraacrylates; pentaacrylates; hexaacrylates; the mixtures between these various acrylates mentioned. It is possible to use, for example, molecules of the O[CH ₂ C(CH ₂ OR)3]2 type where R can be H or COCH=CH ₂ .

It is possible to use PBAE oligomers, this term here includes functional PBAE oligomers and prepolymers, the chain ends of which are functions of the acrylate type; they can be prepared, for example, by reaction of diacrylate compounds with a functional primary amine and/or a functional secondary diamine.

As amine monomer (Y monomer), molecules of the NH2(CH2) _n NH2 type can be used, for example, where n is an integer which can typically be between 1 and 20, and which can be for example 2 ( ethylene diamine) or 6 (hexamethylene diamine, CAS number: 124-09-4). It is also possible to use piperazine, meta-xylylene diamine, pentaethylenehexamine, tris(2-aminoethyl)amine (TREN) or polyethylene imine (PEI).

Amines having an aliphatic carbon skeleton (for example hexamethylene diamine) having many degrees of freedom generally increase the deformation at break of the wall of the microcapsules obtained.

To reduce the breaking deformation of the wall, it is possible to use more rigid multi-amines, for example meta-xylylene diamine.

The nature and concentration of amines and acrylates can be varied.

The ratio of the reactive functions of the monomers Y (-NH functions) and X (acrylate functions) is advantageously greater than 1, and typically between 1 and 5, preferably between 1.2 and 3.8.

According to a particular embodiment of the invention, the monomers X (acrylate) and/or Y (amine) are biosourced. Figure 6 shows the reaction scheme of the aza-Michael addition reaction between a secondary amine and an acrylate (reaction (a)) and the polyaddition reaction between a multifunctional acrylate compound and a multi-amine compound leading to a polymer cross-linked (reaction (b)).

The organic core of the microcapsules may consist of an organic phase comprising an active substance. During the formation of the microcapsule, this organic (oily) phase will be enclosed by the polymeric wall of the microcapsule, which protects it from the environment. Said organic (oily) phase may consist of said active substance, or said active substance may form part of said organic (oily) phase, in which it may in particular be dissolved. The expression “active substance” here refers to the specific purpose for which the microcapsules are intended to be used; as a general rule, given the specificity of the microcapsule product, this purpose is always known during their manufacture.

The active substance can be selected in particular from oils (pure or possibly containing other molecules in solution or in dispersion), such as essential oils, natural and edible oils, vegetable and edible oils, liquid alkanes, esters and fatty acids, or also from dyes, inks, paints, thermochromic and/or photochromic substances, fragrances, products with a biocidal effect, products with a fungicide effect, products with an antiviral effect, products with a phytosanitary effect , active pharmaceutical ingredients, products with cosmetic effects, glues; these active principles possibly being in the presence of an organic vector.

Can be used for example and in a non-limiting way extracts of distillation of natural products such as essential oils of eucalyptus, lemongrass, lavender, mint, cinnamon, camphor, anise, lemon, orange, which may have been obtained by extraction from plant material, or by synthesis.

One can also use other substances such as long chain alkanes (for example tetradecane), which can contain lipophilic molecules in solution.

In general, and depending on the function sought for the microcapsules, it is possible to use any hydrophobic compound, which will thus be naturally dispersed in the form of an emulsion of hydrophobic drops in suspension in an aqueous phase. Many additives can be incorporated into the microcapsule allowing better protection of the organic (oily) phase to be encapsulated, against infrared radiation, ultraviolet radiation, the involuntary penetration of a specific gas or oxidation.

As surfactant, it is possible in particular to use nonionic surfactants, such as polyvinyl pyrrolidone (PVP), polyethylene glycol sorbitan monopalmitate (known under the brand name Tween 20™), polyethylene glycol sorbitan monolaurate (known under the brand name Tween 40 ™), polyethylene glycol sorbitan monooleate (known under the trademark Tween 80™), or ionic surfactants, such as partially neutralized salts of polyacrylic acids such as sodium or potassium polyacrylate or polymethacrylate, or lignosulfate sodium. It is possible to use copolymers of acrylic acid - alkyl acrylate, polyacrylic acid, polyoxyalkylene fatty esters. It is possible to use the surfactants which are cited in Encyclopedia of Chemical Technology, volume 8, pages 912 to 915, and which have a hydrophilic-lipophilic balance (according to the HLB system) equal to or greater than 10.

Other macromolecular surfactants can also be used. Mention may be made, for example, of polyacrylates, methylcelluloses, carboxymethylcelluloses, polyvinyl alcohol (PVA) optionally partially esterified or etherified, polyacrylamide or synthetic polymers possessing anhydride or carboxylic acid functions such as ethylene/maleic anhydride copolymers. Preferably, polyvinyl alcohol can be used as surfactant.

It may be necessary, for example in the case of aqueous solutions of a cellulosic compound, to add a little alkaline hydroxide such as sodium hydroxide, in order to facilitate its dissolution; it is also possible to use such cellulosic compounds directly in the form of their sodium salts, for example. Amphiphilic copolymers of the Pluronics type can also be used. Generally, aqueous solutions containing from 0.1 to 5% by weight of surfactant are used.

The size of the droplets is a function of the nature and the concentration of the surfactant and of the speed of agitation, the latter being chosen all the greater as smaller average diameters of the droplets are desired. In general, the stirring speed during the preparation of the emulsion is 5,000 to 10,000 revolutions per minute. The emulsion is usually prepared at a temperature between 15°C and 95°C.

Generally when the emulsion has been obtained, the agitation by turbine is stopped and the emulsion is agitated using a slower agitator of the usual type, for example of the frame agitator type, typically at a speed of order of 150 to 1,500 revolutions per minute.

The process according to the invention thus leads to homogeneous and fluid suspensions containing, depending on the fillers introduced, generally from 20% to 80% by weight of microcapsules having an average diameter of 100 nm to 100 μm. The microcapsules are spherical. Their diameter can preferably be between 1 μm and 50 μm, and even more preferably between 10 μm and 40 μm. The average diameter of the microcapsules can be determined using laser diffraction (Mastersizer™ type device), a known technique and device for this use.

Depending on the monomers, and in particular the amines, used for the polymerization, the external surface of the wall of the microcapsules can be of an anionic nature or of a cationic nature. An inherent anionic capsule can be obtained when using in aqueous phase amines an amine carrying an anionic charge; such an amine is shown in Figure 19. An inherent cationic capsule can be obtained when using an amine carrying a cationic function; an example is the partial quaternization of multi-amines in the aqueous phase.

The wall of the microcapsules can be modified by adding a coating on the surface thereof. This deposition can be done by adding a polymer dispersed in an aqueous phase which will be deposited on the surface of the capsules. Among these polymers, mention may be made of polysaccharides (cellulose, starch, alginates, chitosan, etc.) and their derivatives. This addition can be done either hot or at room temperature at the end of the interfacial polymerization step.

The wall of the microcapsules can also be modified by adding a radical initiator either in the aqueous phase or in the organic (oily) phase. The addition to the organic phase can be done before and/or after the preparation of the PBAE wall. If the addition is made later, the radical initiator can be diluted in acetone to promote transport into the microcapsules. These initiators can be azo compounds (such as azobis-isobutyronitrile and its derivatives) or peroxide compounds (lauroyl peroxide, etc.). In the case of initiators added to the aqueous phase, these may in particular be water-soluble azo compounds (such as 2,2'-Azobis(2-methylpropionamidine)dihydrochloride) or red-ox systems (ammonium persulphate or potassium in combination with potassium metabisulphate for example). Under an inert atmosphere, the radicals resulting from the decomposition of radical initiators can add to the residual acrylate functions of the wall of PBAE and mechanically reinforce it and/or modify its polarity.

Another way of modifying the wall of the microcapsules is to react the residual amine functions on the surface with water-soluble monofunctional acrylates. Without wishing to be bound by this hypothesis, the inventors believe that by adding Michael, an amino-ester bond would be formed and a functional group would be anchored to the surface. Among the water-soluble acrylates that can be used, mention may be made of acrylic acid, 2-carboxyethyl acrylate, 2-(dimethylamino)ethyl acrylate, 2-hydroxyethyl acrylate, poly(ethylene glycol) acrylates, salt of potassium from 3-sulfopropyl acrylate.

These various possibilities of modifying the wall of the microcapsules after their formation make it possible in particular to confer on them in a targeted manner anionic or cationic properties; this choice will essentially depend on the intended use for these microcapsules.

Here we describe methods to make the wall of microcapsules anionic.

A first method is post-radical modification, using suitable aqueous azo compounds. As such, the compound 4,4′-Azobis(4-cyanovaleric acid) (CAS No: 2638-94-0), available under the reference V501 from FujiFilm Wako, can be used.

A second method is post-modification by the radical route, using redox systems such as APS (ammonium persulphate, CAS no. 7727-54-0) or KPS (potassium persulphate, CAS no. 7727-21-1 ) and reducing agents of the iron or metabisulphite type. A third method is the post-modification by Michael reaction between the secondary and primary amines still present on the surface of the capsules and anionic water-soluble acrylates of the acrylic acid type.

A fourth method is to apply a coating to the microcapsules with anionic polymers such as PAA or PMMA.

Here we describe post-modification methods to render the wall of microcapsules cationic.

A first method is the quaternization of the amines (which are mainly tertiary) present on the surface of the capsules by reaction with an alkyl halide in the aqueous phase.

A second method is post-radical modification, using suitable aqueous azo compounds. As such, the compound 2,2′-Azobis(2-methylpropion amidine)dihydrochloride (CAS No: 2997-92-4), available under the reference V50 from Fuji Film Wako, can be used.

A third method is the post-modification by Michael reaction between the secondary and primary amines still present on the surface of the capsules and water-soluble acrylates. DMAEA may be suitable as a water-soluble acrylate.

The microcapsules according to the invention can be prepared with very different mechanical properties; these mechanical properties can be tailored to the intended use, as will be explained in greater detail below. They are represented in the context of the present invention by the indentation force at break of the microcapsule, measured during a nanoindentation test at room temperature with a Berkovich type pyramidal tip, and by the glass transition temperature determined with common differential thermal analysis techniques. This indentation force at break depends on the intrinsic mechanical characteristics of the wall material, as well as the thickness of the wall.

In the context of the present invention, three types of microcapsules are distinguished, which are designated here by the adjectives “fragile”, “brittle” and “unbreakable”. The so-called fragile microcapsules are characterized by an indentation force at break of less than 300 pN and preferably by a Tg value of less than 33° C., and in this case this Tg value is preferably less than 32° C. and even more preferably below 31°C. They are preferably characterized by an indentation force at break of less than 250 pN and preferably by a Tg value of less than 32°C, and in this case this Tg value is preferably less than 31°C and even more preferably below 30°C. They are characterized even more preferably by an indentation force at break of less than 200 pN and preferably by a Tg value of less than 32°C, and in this case this Tg value is preferably less than 31°C and even more preferably below 30°C.

These microcapsules can have a volume ratio of encapsulated substance relative to the wall (this ratio is known by the English term “core/shell ratio”) which can reach 95/5 or even 96/4. In other words, the thinness of their wall contributes to their fragility.

Fragile microcapsules are used when rapid release of the active substance they contain is desired. This release can be facilitated by a temperature above room temperature. By way of example, such microcapsules can be used in compositions for the treatment of the hair and the scalp, which are exposed to a temperature above room temperature and to a very low mechanical pressure during their application. Another example of the use of active substances that can be enclosed in fragile microcapsules are the pigments or dyes used in cosmetic preparations.

The so-called brittle microcapsules are characterized by an indentation force at break of between 200 pN and 5000 pN, and preferably between 300 pN and 5000 pN. Microcapsules with a breaking force between 200 pN and 300 pN preferably exhibit a Tg value of at least 33°C. For the microcapsules with a breaking force greater than 300 pN, it is preferable that their Tg value be between 30°C (preferably between 33°C) and 80°C.

These brittle microcapsules therefore have a low elongation at break, which leads to the fragmentation into pieces of the wall under a mechanical stress of sufficient force, for example when rubbing a surface which has been coated with these brittle microcapsules. These microcapsules can be obtained with so-called rigid multi-amine monomers, such as meta-xylylene diamine; these compounds increase the Tg value of the wall. Another possibility to lead to brittle microcapsules is to increase the crosslinking density of the wall to limit its elastic deformation. Mention may be made in this respect of pentaethylene hexamine which leads to a large quantity of knots.

Brittle microcapsules can be used for applications in which it is desired to be able to cause the release of the active substance by the application of mechanical pressure or by a chemical modification of the microcapsule which modifies its mechanical properties. An example is the use of microencapsulated active substances in blowing agents and sealants.

The wall of the brittle microcapsules may exhibit porosity.

In general, the wall of a microcapsule represents a diffusion barrier for the chemical species contained by the wall of the microcapsule; this is one of the goals of micro-encapsulation. However, depending on the use envisaged for the microcapsules, it may be desirable to have a certain permeability of the wall to the molecules it contains. This permeability of the wall is also called its "porosity", because at the atomic level, the permeability of the wall is not homogeneous over the entire surface of the wall: within the polymer there are more permeable zones than others, which are called "pores".

In general, it is therefore desirable to be able to adapt the permeability of the wall to the intended use of the microcapsule. It is known that the permeability of a microcapsule wall is both determined by the nature and structure of its material, and it decreases when the thickness of the wall increases.

More particularly, for microcapsules having a PBAE wall, the porosity of the wall depends on the thickness of the wall and its chemical characteristics. The main chemical characteristic is the degree of cross-linking of the wall: a low degree of cross-linking generally results in greater porosity. For example, the knot density is low when the POSS™-acrylate monomer is used compared to an acrylate of the dipentaerythritol penta-/hexa-acrylate type: there are around fifteen carbon atoms between the knots instead of from five to seven: the POSS makes it possible to increase the rigidity of the walls and at the same time leads to a certain porosity. Using a multi-acrylate like the one shown in Figure 20 results in a wall as stiff as that obtained with POSS, but the network is denser and the porosity lower than with POSS.

The modulation of the porosity can also be done by mixtures of multi-acrylate compounds with a combination of short compounds of the diacrylate and multi-acrylate types (for example dipentaerythritol penta-/hexa-acrylate). This makes it possible to ensure that the majority of the acrylate functions have reacted because the short compound is more mobile and makes it possible to finish the crosslinking.

The porosity characteristic of the wall is irrelevant for fragile-type microcapsules, which are bound to release their contents rapidly by breaking the wall.

The so-called unbreakable microcapsules are characterized by an indentation force at break greater than 5,000 pN, preferably greater than 6,000 pN, and even more preferably greater than 7,000 pN. They preferably have a Tg value greater than 80°C, preferably a Tg value greater than 85°C, and are even more preferably a Tg value greater than 90°C.

According to a first variant, they have an indentation force at break greater than 5,000 pN and a Tg value greater than 80°C, preferably greater than 85°C, and even more preferably greater than 90°C.

According to a second variant, they have an indentation force at break greater than 6,000 pN and a Tg value greater than 80°C, preferably greater than 85°C, and even more preferably greater than 90°C.

According to a third variant, they have an indentation force at break greater than 7,000 pN and a Tg value greater than 80° C., preferably greater than 90° C., and even more preferably greater than 100° C.

It should be noted that the "unbreakable" nature of these microcapsules can result from two different and even contradictory characteristics: either the microcapsules are so rigid that they cannot be broken with the indentation force applied, or they are so elastic that they deform under the applied pressure, but without breaking. It is also possible to vary the porosity of the unbreakable microcapsules, by the choice of appropriate monomers as described in relation to the brittle microcapsules. For certain uses, the so-called unbreakable microcapsules must not have significant porosity. The absence of porosity makes it possible to use them in applications where it is not desired for the active substance to be able to leave the microcapsule, either by breaking the wall or by passing through the wall. It is thus possible to encapsulate thermochromic substances or photochromic substances, intended to fulfill this function for a long period. Another use for which total hermeticity of the wall of the microcapsule is required is that of encapsulated phase change materials.

For other uses, for example for the diffusion of perfumes over a long period, the wall must be unbreakable, to avoid a too rapid release of the perfume, but must all the same allow the perfume to cross the wall: one will choose for that a wall of unbreakable type and porous type.

The increase in the mechanical properties of the wall can be obtained by introducing into the wall organic or inorganic groups which will serve as reinforcement for the wall. For example, the monomer POSS™-acrylate, comprising a siloxane cage modified by eight acrylate functions), gives the wall of the microcapsule an increase in Young's modulus. It is the same for acrylate whose structure is shown in figure 20.

The glass transition temperature Tg of the microcapsules can be determined according to techniques known to those skilled in the art, with commercially available devices, for example a TGA 8000 type thermogravimetry device manufactured by the company PerkinElmer. For this measurement, the microcapsules are emptied and dried at ambient temperature, then a sample of the order of 10 mg to 50 mg (typically 25 mg) is transferred into the measuring cup. The mixture is heated under nitrogen with a heating rate of approximately 20° C./min under a flow of nitrogen (20 ml/min). This measurement can also be carried out on a sheet of polymer obtained under similar reaction conditions. The porosity of the walls can be determined with the same device on the filled microcapsules: a sample of the same quantity is maintained at a fixed temperature (for example 70° C.) under a flow of nitrogen for approximately 17 h to 20 h, by recording mass loss. The microcapsules, and in particular their wall, according to the invention are (bio)degradable. Biodegradation can be determined for example by one of the methods described in the document "OECD Guidelines for the Test/s of Chemicals: Ready Biodegradability" (adopted by the Council of the OECD on July 17, 1992) . In particular, the manometric respirometry test (method 301 F) can be used. Preferably, this test is carried out on emptied and washed microcapsules, so that the biodegradation of the content of the microcapsules does not interfere with the test, the purpose of which is to characterize the biodegradation of the material forming the wall of the microcapsules. Preferably, the microcapsule according to the invention, and/or its wall, shows a biodegradation of at least 80%, preferably of at least 83%, more preferably of at least 85%, measured after an incubation of 10 days using said 301 F method. With this same method, after incubation for 28 days, the microcapsules according to the invention preferably show a biodegradation of at least 90%, preferably of at least 95% , and even more preferably at least 98%.

The microcapsules according to the invention can be the subject of many uses. In general, they can be used in different ways.

The primary reaction mixture can be used as it is, optionally after having adjusted its pH. It is also possible to modify the surface of the microcapsules, as described above; in this case, the reaction mixture of this modification reaction (this reaction mixture being referred to here as “secondary reaction mixture”) can be used as it is (optionally after adjustment of the pH).

In all cases, dry microcapsules can be used, with or without washing (in the latter case, the reaction mixture is dehydrated).

The microcapsules are used dry especially in two cases: when it is necessary to integrate them in a hydrophobic medium (for example in a hydrophobic plastic material, such as a silicone), and when it is desired to observe a color change at through the wall of the microcapsule; this will be the case when the microcapsule contains a thermochromic or photochromic product.

The use of washed microcapsules is generally necessary for pharmaceutical applications, for food applications, and for most cosmetic applications, because the reaction mixtures may contain molecules that are toxic, allergenic or otherwise incompatible with the intended use, or generally undesirable. The microcapsules according to the invention have numerous uses which will be described below. For all the uses for which it is indicated that the reaction mixture can be used directly, this refers to the so-called primary reaction mixture as it results from the succession of the synthesis steps (a), (b) and (c). ) described above, optionally after adjustment of the final pH; this also refers to the so-called secondary reaction mixture which results from a reaction aimed at giving the external wall of the microcapsule anionic or cationic properties. It is also possible to use a slurry prepared by purification of the reaction mixture (primary or secondary), or a slurry prepared from isolated microcapsules, possibly after washing and/or drying of the microcapsules, or a preparation comprising a mixture of the reaction mixture (primary or secondary) or one of the slurries which have just been described, optionally after addition of solvents or other functional constituents. Direct use of a reaction mixture is the simplest use, but purification or isolation or drying of the microcapsules, which require additional process steps, may have advantages.

For all the uses according to the invention, it is possible to use microcapsules according to the invention of a single type (composition and wall thickness), comprising one or more encapsulated active substances, or several types of microcapsules according to the invention (for example of the same wall composition but of different wall thickness, to have release levels, or else of different wall composition) comprising one or more active substances, in the same microcapsule or in separate microcapsules.

The microcapsules can be used in cosmetic products and care products intended to be applied to the face and to the body, in particular to stabilize and/or vectorize one or more specific active substances and to control their release. Said cosmetic products and care products may in particular be creams and lotions for the body, creams and lotions for the face, shower gels, bath gels, UV filter products, more particularly self-adaptive make-up correcting their tint depending on ambient solar or electric lighting and other products comprising micro-encapsulated active substances intended to be released in a controlled and targeted manner, in particular for vectorization in the skin, for stabilization of pigments and/or dyes, for covering of wrinkles. Said cosmetic products and care products intended to be applied to the body may contain as active substances microencapsulated catalysts and/or enzymes, and/or microencapsulated wrinkle recoverers.

They may also be depilatory waxes, comprising thermochromic agents and/or agents for temperature control and/or active products with controlled release, said agents and active products being microencapsulated according to the invention. It can also be products for hair and scalp care, and in particular shampoo, conditioners, hair dyes. They may also be disinfectant and/or deodorant products and products to control the smell of objects in contact with the body to control or limit or mask body odor; as such, the microencapsulated active products can in particular be antiperspirants, perfumes, essential oils and/or fragrances.

To use the microcapsules according to the invention in cosmetic products and care products intended to be applied to the face or body, it is generally preferred not to use the reaction mixture directly, but to wash, and preferably to isolate the microcapsules; in one embodiment, the microcapsules are isolated and dried before incorporating them into a cosmetic or care product preparation. For use in cosmetic products and care products, it is preferred to use microcapsules of the fragile, brittle or porous type, as the case may be; they are preferably anionic, but can also be cationic (in particular for shower gel and bath products, and for hair care products). For shower gel and bath products, the use of dry microcapsules or unbreakable type microcapsules does not present a significant advantage. For use in deodorants and for odor control the use of fragile or unbreakable type microcapsules is not preferred.

To incorporate the microcapsules into a depilatory wax preparation, the reaction mixture can also be used directly, and/or these microcapsules are preferably of the unbreakable and anionic types.

For most uses for cosmetic products, microcapsules of the anionic type, washed and/or isolated, possibly dried, are preferred. To incorporate microcapsules containing substances capable of filtering out UV radiation in cosmetic products, microcapsules of the fragile or unbreakable type, preferably anionic, are advantageously used. To encapsulate of the pigments or dyes for use in these cosmetic compositions, microcapsules of the fragile, brittle or unbreakable type, preferably anionic, are advantageously used. To encapsulate other dermatological or cosmetic active principles, microcapsules of the porous or brittle type, preferably anionic, are used.

The microcapsules can be used to coat cosmetic textiles. For these uses, the microcapsules may contain antioxidant products, anti-cellulite products, products capable of stimulating blood circulation, as well as anti-mold, antimicrobial, bactericidal and virucidal products. For most of these uses, the reaction mixture can be used directly, although this is not preferred. The microcapsules can be of the porous type; for antioxidant and anti-cellulite products as well as for antimicrobial, bactericidal and virucidal products, it is also possible to use microcapsules of the brittle type. For all these uses, the microcapsules can be of the anionic or cationic type.

The microcapsules can contain active pharmaceutical principles and can be incorporated into pharmaceutical preparations which are intended to be used, in human or veterinary medicine, in particular orally, nasally, intra-bloodally, rectally, or by topical application, for example cutaneous or ocular. These uses can in particular serve to release in a targeted manner the content of the microcapsules, which is typically a pharmaceutical active principle, in a specific chemical environment, this environment being for example characterized by a specific pH value. For all these pharmaceutical preparations the washed microcapsules are used. They are typically of the brittle type, and preferably of the porous type; they can, depending on the case, be of the anionic or cationic type.

To coat medical textiles, such as dressings, intended to come into contact with the skin or with wounds, the same type of microcapsule walls are used as for cosmetic textiles, but after washing; these microcapsules contain active pharmaceutical ingredients.

Said pharmaceutical active principles can in particular be hormones, corticosteroids, antiseptics, anti-oestrogens, antifungals, antibiotics, vasoactive agents, antiglaucoma agents, beta-blocking agents, cholinergic agents, sympathomimetic agents, inhibitors carbonic anhydrase, mydriatic agents, virostatic agents, antitumor agents, antiallergic agents, vitamins, anti-inflammatory agents, immunosuppressive agents, anesthetic agents, ciclosporin, antioxidants, peptides, proteins, enzymes, polyphenols, and combinations and/or mixtures of these agents.

The microcapsules may contain adhesives and/or glues and be used in the preparation formulation of adhesives and/or glues. Preferably, the reaction mixture is used directly, without washing. Preferably, microcapsules of the brittle type, of the anionic or cationic type are used.

The microcapsules may contain photochromic agents, in particular for hair dyes and for protection products against sunlight. For hair care products, the reaction mixture is preferably used without washing, for products for protection against sunlight, the washed microcapsules are preferably used. For these two applications, it is possible to use microcapsules of the fragile type or of the unbreakable type, and preferably of the anionic type.

Reversible photochromic agents, which have many applications such as anti-counterfeiting, recreational applications, writing and detection of UV radiation can also be contained in cationic type microcapsules.

The microcapsules may contain erasable or non-erasable inks, possibly scented, intended in particular for writing accessories and toys. These microcapsules can be of the brittle type or of the unbreakable type, and preferably of the anionic type. The reaction mixture can be used without washing.

The microcapsules may contain detergent products, in particular for wet cleaning or for dry and/or waterless cleaning. These microcapsules can be of the brittle type and/or of the porous type. They can be of the anionic or cationic type. The reaction mixture can be used without washing, and/or dried microcapsules.

The microcapsules can be used in products for the care of the teeth and the mouth, where they can contain specific active products. These microcapsules are preferably used after washing, possibly after drying. The microcapsules can be fragile type, brittle type, unbreakable type, and/or porous type. They may contain active deodorizing substances,

The microcapsules can be used in food preparations. In this use, they contain active food products, such as flavorings, flavor enhancers, vitamins, nutritional additives, preservatives. Washed, preferably isolated, optionally dried microcapsules are used. They can be fragile, brittle or porous. They may be of the anionic type.

The microcapsules can be used to turn liquid oil into powder. Ob can use these microcapsules containing the liquid oil after washing and drying to incorporate them into cosmetic or food preparations. For this, microcapsules of the brittle type, which are preferably of the anionic type, are preferred.

The microcapsules may contain insecticides, repellents, fungicides, anti-moss products, termite treatment products. These microcapsules can be incorporated into numerous products, in particular phytosanitary products, paints, coatings, textiles, detergents, plastic materials, wood. The reaction mixture can be used directly, but it is also possible to use (especially in the case of microcapsules containing insecticides) washed, preferably isolated, optionally dried microcapsules. For all these uses, the microcapsules are advantageously of the fragile or porous type. They can be of the anionic type, but for repellents also of the cationic type. These microcapsules can find applications in the field of agriculture.

Other uses in the field of agriculture relate to microcapsules containing additives for the cultivation of plants, and/or fertilizers. Microcapsules of the fragile, porous or brittle type are used, which can be of the anionic or cationic type. They are preferably washed.

Phytosanitary products can also be encapsulated by the method according to the invention; the reaction mixture can be used. The microcapsules are advantageously of the fragile or porous type; they can be of the anionic or cationic type. In the veterinary field, microcapsules can be used to encapsulate pharmaceutical or dermatological active principles, or else for the care of the coat, such as vermifuges, antiparasitics or agents for controlling or limiting odors. Advantageously, washed and dried microcapsules are used here, of the fragile, brittle, unbreakable or porous type, which may be anionic or cationic. They can in particular be incorporated into care products, pharmaceutical compositions, and food products; the incorporation of microcapsules containing pharmaceutically active substances into food products is a particularly interesting use.

The microcapsules can be used to treat or coat textile products or textile fibres, in particular technical ones. In this use, they may contain biocidal products, deodorizing products, self-cleaning products, self-healing products and/or self-repairing products. For all these uses, the reaction mixture can be used directly. The microcapsules can be of the fragile type, of the porous type (in particular for biocidal, deodorizing and self-cleaning products) or of the brittle type (in particular for self-healing and self-repairing products; with these two products it is also possible to use microcapsules, washed or not). The microcapsules can be of the anionic or cationic type. These microcapsules can also be used to treat shoes, especially on the inside.

Still in the textile field, the microcapsules can contain detergent, softener, biocidal or antistatic products, anti-stain products; here, the reaction mixture can be used directly, and the microcapsules are advantageously of the porous or brittle type, and of the anionic and cationic type.

The microcapsules can be used in compositions for waterproof or water-repellent coatings; these coatings can be applied to textile surfaces or leather surfaces. The reaction mixture can be used directly. The microcapsules are preferably of the fragile or porous type and of the anionic type. They may contain hydrophobic compounds, in particular fatty compounds or fluorinated compounds.

The microcapsules can be used for the treatment of bedding (such as: mattresses, pillows, blankets, sheets, undersheets), luggage, fabrics and household equipment (such as: curtains, furniture with fabrics, furniture and other leather goods, cushions). For these uses, the microcapsules may contain biocidal products and/or repellent products (and in particular anti-mite products, anti-lice products, anti-mite products, anti-mosquito products), anti-stain products, perfumes, essential oils, fragrances and/or flavorings. For all these uses, the reaction mixture can be used directly. The microcapsules can be porous or brittle. They may be of the anionic type.

The microcapsules can be used in the formulation of deodorant and/or disinfectant products, and anti-foam and anti-fungal products. The active substances are oily, natural or synthetic products. The microcapsules are preferably of the porous type and of the anionic type; the reaction mixture can be used directly.

Used in detergent products, the microcapsules can contain anti-foam products, enzymes and/or perfumes. The reaction mixture can be used directly. The microcapsules are preferably of the porous or brittle type, and of the anionic type.

The microcapsules can be used to coat building materials or thermal insulation products. For these uses, they may contain phase change materials (PGM) which provide effective thermal stabilization. These phase change materials may for example be active products based on paraffin or based on fatty acids (such as dodecanoic acid or esters, in particular methyl or decyl, of fatty acids), or else waxes vegetable or animal, such as beeswax. These active products advantageously have a melting point of between about 40°C and about 100°C.

For this use, the reaction mixture comprising the microcapsules can be used directly; the thermal insulation products can also advantageously be prepared with dry microcapsules. For all these uses, the microcapsules can be of the unbreakable type. They may be of the anionic type; to coat construction materials they can also be of the cationic type. Microcapsules containing phase change materials can also be used to cool batteries. For any use of phase change materials, the microcapsules must be of the unbreakable type, and their porosity must be as low as possible. The microcapsules can be used in preparations ensuring watertightness, to be applied to solid materials (for example in the building sector) or flexible; in these preparations they may contain in particular sealing agents and/or expansion agents. The reaction mixture can be used directly. The microcapsules can be of the brittle type. They may be of the anionic type.

The microcapsules can contain lubricating and/or anti-friction products, or on the contrary non-slip products, essential oils, fragrances, perfumes and/or flavorings. These microcapsules can in particular be used on or in floor coverings. For all these uses, the reaction mixture can be used directly. The microcapsules can be of the brittle or unbreakable type. They may be of the anionic type.

The microcapsules may contain dyes and/or pigments. These microcapsules can be used in particular for dyeing with solvents, for transfer printing, for inkjet printing, for electrostatic printing, for screen printing or other printing techniques. For all these uses, the reaction mixture can be used directly. For solvent dyes, dried microcapsules can also be used. The microcapsules can be of the fragile or unbreakable type. They may be of the anionic type.

In papermaking and printing, the reaction mixture can be used directly for coating paper, or for incorporation into a composition for making paper. For the manufacture of self-copying paper, microcapsules of the brittle type and of the anionic type are preferred. For scented impressions of the scratch & sniff or rub & sniff type, used for certain packaging, press or advertising products, it is also possible to use porous and unbreakable microcapsules; they are typically incorporated into inks.

It is possible to incorporate microcapsules according to the invention in inks and paints to manufacture road markings on the ground, panels or signage strips, in particular reflective. The reaction mixture can be used directly. The microcapsules are preferably of the unbreakable type, and of the anionic type.

The microcapsules can be used in self-healing compositions, which can be surface coatings used in paints, varnishes, inks, on rigid surfaces such as cement and concrete, and more generally on building materials, but also on flexible surfaces. Said self-healing compositions can also be incorporated into polymers and composites. The reaction mixture can be used directly, but in certain cases the residual impurities (in particular the residual amines) can interfere, and it is then necessary to wash the microcapsules. The microcapsules are preferably of the porous type, and of the anionic type. If the self-repair must take place following an impact, microcapsules of the brittle type are preferred.

A very particular use is that of self-repairing substances contained in washed and possibly dried microcapsules, used in the encapsulation materials of solar panels, and in particular for use in the aeronautical or space field. These encapsulation materials are generally polymers. Typically, microcapsules of the breakable or unbreakable type are used, which may be, depending on the nature of the material in which they will be incorporated, of the anionic or cationic type.

The microcapsules can be used in compositions having fire retardant and extinguisher function. The reaction mixture can be used directly. The microcapsules are preferably of the brittle type and of the anionic type. They may contain brominated alkanes of general formula C _n H2n+2-xBr _x .

The microcapsules can contain thermochromic substances to detect and/or visualize the crossing of a temperature threshold, which has many applications such as depilatory wax, packaging for food products to be heated, labels for refrigerated products allowing indicate a possible break in the cold chain, coatings allowing the indication of excessive stress or impacts following an accident, wear or misuse, in particular on plastic or composite parts, on mountaineering ropes, technical fabrics or protective helmets (motorcycle, bicycle, etc.). The reaction mixture can be used as it is, with unbreakable type microcapsules; they can be of the anionic or cationic type.

Unbreakable microcapsules having a thermochromic function can be used in holding and positioning guides and standards. They may be of the anionic type. The microcapsules can contain essential oils, fragrances, perfumes, and/or flavorings, which can be used in many products, by mixing into the product or by applying a coating to the product. For all these uses, the reaction mixture can be used directly. The microcapsules can be of the brittle or unbreakable type. They may be of the anionic type.

More generally and following the same principles as above, are also concerned the fields of application such as antibacterial protection and against bad odors, uses in the field of the automobile and in particular of the passenger compartment, including the atmospheres of well-being and relaxation, maintenance of filters and decontaminants for military and civil sanitary applications, catalysts and surface modification agents.

For the decontamination of filters, in particular air filters, in particular for military decontamination, the reaction mixture can be used directly. The microcapsules are preferably porous type and anionic type.

In the automotive sector (automotive equipment, interior, accessories) the reaction mixture can be used directly. The microcapsules are preferably of the unbreakable type, and of the anionic type.

For technical catalysts and enzymes and surface modifiers, the reaction mixture can be used directly. The microcapsules are preferably of the brittle type and of the anionic type.

Examples

To enable those skilled in the art to reproduce the invention, examples of implementation are given here; they do not limit the scope of the invention.

Preparation of perfumed microcapsules based on a diamine (HMDA)

(i) Preparation of the emulsion

11.0 g of essential oil (Eucalyptus) was placed in a beaker, and the multi acrylate monomer (Dipentaerythritol penta-/hexa-acrylate mixture) (0.39 g, 0.71 mmol) was dispersed in the essential oil under magnetic stirring (350 rpm). Stirring was maintained until the solution became homogeneous; a heating step has been added if necessary. The essential oil/organic monomer combination was gradually added to the aqueous solution of the surfactant prepared beforehand (40 g, PVA 2% by mass); the mixture was homogenized using an Ultraturrax™ IKA T10 at 9500 rpm for 3 min at room temperature to form an emulsion.

(ii) Microencapsulation

In a double-walled reactor, equipped with an IKA mechanical blade stirring system, preheated to 50°C, the previously prepared emulsion was introduced and stirred at a speed of 250 rpm. When the emulsion reached 50°C, the solution of diamine (Hexamethylene diamine HMDA) (0.17 g, 1.46 mmol) in 5 g of 2 wt% PVA solution was added dropwise using of a syringe and with stirring (250 rpm). During the reaction, samples at different reaction times were taken and analyzed by optical microscopy and Fourier transform infrared spectroscopy (FTIR) in order to monitor the formation of the microcapsules.

The total amount of monomers used was ~0.56 g. The amine was used in excess relative to the acrylate monomer so as to have a ratio of -NH/acrylate functions = 1.6. The essential oil/water mass ratio is equal to 0.24.

The analysis of the microcapsules can be done by microscopy after a drying step. This analysis makes it possible to ensure the stability of the microcapsules once isolated. A second analysis consists of adding a few drops of a fluorescent dye (Nile Red) to the dried microcapsules. Nile Red, a lipophilic chromophore which fluoresces only in an organic phase, makes it possible to verify that the core of the microcapsule still contains organic phase and that the microcapsules are filled.

Figure 2 shows an optical microscopy image of the reaction medium after 5 h of reaction. The microcapsules are spherical, with a diameter between about 10 µm and about 25 µm. FIG. 3 shows the FTIR spectrum of the microcapsules isolated from a slurry after 6 h of reaction (after washing with acetone, followed by three cycles of centrifugation and drying in an oven). There are characteristic vibrations of NH bonds around 3300 cm ^-1 to 3400 cm ^-1 , as well as a narrow band characteristic of a C=O bond around 1727 cm ^-1 .

Figure 4 shows an optical micrograph of microcapsules dried on a glass slide. Their diameter is about 30 pm to 35 pm. Figure 5 shows a micrograph of microcapsules dried on a glass slide in raking light (left) and in fluorescent light (right) after adding a few drops of the fluorescent dye Nile Red. Intense emission under fluorescent light shows that the core of the microcapsule contains an organic phase.

Example 2: Preparation of perfumed microcapsules based on a diamine (HMDA)

(i) Preparation of the emulsion 11.0 g of a thermo-chromic solution (blue 10°) were introduced into a beaker, placed in an oil bath and heated to 130° C. with magnetic stirring (350 rpm). Stirring was maintained until the thermo-chromic solution became homogeneous and transparent. The thermo-chromic solution was cooled, and when its temperature reached 50°C, the (multi)acrylate monomer (Dipentaerythritol penta-/hexa-acrylate mixture) (0.39 g, 0.71 mmol) was dispersed under magnetic stirring. (350rpm). Stirring is maintained until the solution becomes homogeneous. The thermochromic/organic monomer combination was added gradually to the aqueous solution of the surfactant prepared beforehand (40 g, PVA 2% by weight); the mixture was homogenized using an Ultraturrax™ IKA T10 at 9500 rpm for 3 min at room temperature to form an emulsion

(ii) Microencapsulation

In a double-walled reactor, equipped with an IKA mechanical blade stirring system, preheated to 50°C, the previously prepared emulsion was introduced and stirred at a speed of 250 rpm. When the emulsion reached 50°C, the solution of diamine (Hexamethylene diamine HMDA) (0.17 g, 1.46 mmol) in 5 g of 2 wt% PVA solution was added dropwise using of a syringe and with stirring (250 rpm). During the reaction, samples at different reaction times were taken and analyzed by optical microscopy.

The total amount of monomers used was ~0.56 g. The amine was used in excess relative to the acrylate monomer so as to have a ratio of -NH functions / acrylate = 1.6. The thermochromic solution/water mass ratio is 0.24.

The dried microcapsules show a reversible color change with a reversible color change at a temperature of 10°C. These same capsules can, moreover, be heated in an oven at 130° C. for 30 min without modifying their thermochromic properties (FIG. 7).

Example 3: Degradability test of a poly(beta-amino ester)

A first degradability test was carried out according to the following procedure:

(1) Synthesis of poly(beta-amino ester)

In a beaker, Hexamethylene diamine HMDA monomer (1.0 g, 8.6 mmol) was dissolved in THF (4.0 g) and added to a solution of (multi)acrylate monomer (trimethylolpropane triacrylate) (1.8 g, 6.1 mmol) dissolved in 2.5 g of THF. The mixture was placed in a pillbox then placed in an oil bath at 50°C.

The amine was used in excess relative to the acrylate monomer so as to have a ratio of -NH functions / acrylate = 2. The polymer recovered after reacting for 5 hours was washed three times with acetone and dried in an oven.

(2) Degradation of poly(beta-amino ester)

The degradation of the poly(beta-aminoester) was carried out according to the following protocol:

20 mg of the polymer dissolved in 1 mL of a sodium hydroxide solution (3M, in deuterated water D2O, pH~14) is introduced into a flask fitted with a magnetic stirrer. Since the polymer is cross-linked, it is not soluble in the aqueous phase.

Figure 8 shows that the poly(beta-amino ester) dissolved in the aqueous phase, characterizing efficient polymer degradation under these accelerated degradation conditions.

Preparation of perfumed microcapsules based on a triamine (TREN)

(i) Preparation of the emulsion

11.0 g of essential oil (Eucalyptus) was placed in a beaker, and the multi acrylate monomer (Dipentaerythritol penta-/hexa-acrylate mixture) (0.39 g, 0.74 mmol) was dispersed in the essential oil under agitation. The essential oil/organic monomer combination was added gradually to the aqueous solution of the surfactant prepared beforehand (40 g, PVA 2% by weight); the mixture was homogenized using an Ultraturrax™ IKA T10 to form an emulsion.

(ii) Microencapsulation

In a double-walled reactor, equipped with an IKA mechanical blade stirring system, the previously prepared emulsion was introduced. An aqueous solution of tris(2-aminoethyl)amine TREN (0.145 g, 0.99 mmol) in 5 g of 2 wt% PVA solution was added with stirring at a temperature between 50°C and 60°C.

Preparation of thermochromic microcapsules based on a triamine

(i) Preparation of the emulsion

11.0 g of a thermochromic solution were introduced into a beaker and stirred while hot, the multi-acrylate monomer (Dipentaerythritol penta-/hexa-acrylate mixture) (0.39 g, 0.74 mmol) was dispersed therein under hustle. The thermochromic/organic monomer combination was gradually added to the aqueous solution of the surfactant prepared beforehand (40 g, PVA 2% by mass); the mixture was homogenized using an Ultraturrax™ IKA T10 to form an emulsion.

(ii) Microencapsulation In a double-walled reactor, equipped with an IKA mechanical blade stirring system, the previously prepared emulsion was introduced at a temperature of approximately 50°C to 60°C. An aqueous solution of tris(2-aminoethyl)amine TREN (0.145 g, 0.99 mmol) in 5 g of 2 wt% PVA solution was added with stirring at a temperature between 50°C and 80°C.

Preparation of microcapsules based on a biogenic monomer

(i) Preparation of the emulsion

11.0 g of essential oil (Eucalyptus) was placed in a beaker, and the multi acrylate monomer (Dipentaerythritol penta-/hexa-acrylate mixture) (0.39 g, 0.74 mmol) was dispersed in the essential oil under agitation. The essential oil/organic monomer combination was gradually added to the aqueous solution of the surfactant prepared beforehand (40 g PVA 2% by weight); the mixture was homogenized using a

Ultraturrax™ IKA T10 to form an emulsion.

(ii) Microencapsulation

In a double-walled reactor, equipped with an IKA mechanical blade stirring system, the previously prepared emulsion was introduced, the aqueous solution of diamine (Butane-1,4-diamine (Putrescine)) (0.13 g, 1.47 mmol) in 5 g of 2 wt% PVA solution was added with stirring at a temperature between 50°C and 60°C.

Figure 10 shows an optical microscopy image of the capsules after 24 h of reaction. The microcapsules are spherical, with an average diameter between about 10 µm and about 30 µm.

Preparation of microcapsules based on polyethylene imine (PEI)

(i) Preparation of the emulsion

11.0 g of essential oil (Eucalyptus) was placed in a beaker, and the multi acrylate monomer (Dipentaerythritol penta-/hexa-acrylate mixture) (0.39 g, 0.74 mmol) was dispersed in the essential oil under agitation. The essential oil/organic monomer combination was gradually added to the aqueous solution of the surfactant prepared beforehand (40 g PVA 2% by weight); the mixture was homogenized using an IKA Ultraturrax™ to form an emulsion.

(ii) Microencapsulation

In a double-walled reactor, equipped with a mechanical stirring system with IKA blades, the emulsion prepared previously was introduced. A solution of polyethylene imine (PEI) (1.78 g, 1.48 mmol) in 5 g of 2 wt% PVA solution was added with stirring at a temperature between 50°C and 60°C. Figure 11 shows optical microscopy images of the capsules after 24 h of reaction. The microcapsules are spherical, with an average diameter ranging from about 10 µm to about 30 µm

Example 8: Preparation of scented microcapsules (shell/PI ratio=3.4%)

(i) Preparation of the emulsion

193.6 g of essential oil (Eucalyptus) was placed in a beaker, and the multi acrylate monomer (Dipentaerythritol penta-/hexa-acrylate mixture) (4.5 g, 8.5 mmol) was dispersed in the essential oil under agitation. The essential oil/organic monomer combination was added gradually to the aqueous solution of the surfactant prepared beforehand (255.9 g PVA 2% by weight); the mixture was homogenized to form an emulsion.

(ii) Microencapsulation

In a double-walled reactor, equipped with an IKA mechanical blade stirring system, the previously prepared emulsion was introduced. A solution of diamine (Hexamethylene diamine HMDA) (2.01 g, 17.2 mmol) in 44.1 g of a 2 wt% PVA solution was added with stirring at a temperature between 50°C and 60°C . It was left to react for 2 h at 50°C and for 5 h at 60°C.

Example 9: Preparation of scented microcapsules

(i) Preparation of the emulsion

11.0 g of a mixture of 80% Papaya Pineapple perfume (reference RS42370 from Technicoflor in Allauch (France)) and 20% methyl myristate were placed in a beaker, and the multi acrylate monomer (Dipentaerythritol penta- /hexa-acrylate) (0.39 g, 0.74 mmol) was dispersed into the fragrance with stirring. The fragrance/organic monomer combination was added gradually to the aqueous solution of the surfactant prepared beforehand (40 g PVA 2% by mass); the mixture was homogenized using an Ultraturrax™ IKA T10 to form an emulsion.

(ii) Microencapsulation

In a double-walled reactor, equipped with a mechanical stirring system with IKA blades, the emulsion prepared previously was introduced. A solution of diamine (Hexamethylene diamine HMDA) (0.17 g, 1.49 mmol) in 5 g of a 2 wt% PVA solution was added with stirring at a temperature between 50°C and 60°C. It was left to react for 2 h at 50°C and for 5 h at 60°C. Preparation of carbonless microcapsules (PI shell ratio 3.4%)

(i) Preparation of the emulsion

193.6 g of an internal phase (Dye) was placed in a beaker, and the multi acrylate monomer (Dipentaerythritol penta-/hexa-acrylate mixture) (4.5 g, 8.5 mmol) was dispersed in the internal phase under agitation. The whole was added gradually to the aqueous solution of the surfactant prepared beforehand (255.9 g, PVA 2% by weight); the mixture was homogenized to form an emulsion.

(ii) Microencapsulation

In a double-walled reactor, equipped with an IKA mechanical blade stirring system, the previously prepared emulsion was introduced. An aqueous solution of diamine (Hexamethylene diamine HMDA) was added, with stirring at a temperature between 50°C and 60°C.

(iii) Use of microcapsules in carbonless paper

These microcapsules were applied to a sheet of paper, according to known methods, and used in a self-copying system. Figure 12 shows the result, which is quite satisfactory. Preparation of thermochromic microcapsules based on the monomer

POSS@octa(acrylate)

(i) Preparation of the emulsion

20.0 g of thermochromic, and polyoctahedral silsesquioxanes carried from eight acrylate functions (POSS@octa(acrylate), CAS No. 1620202-27-8, purchased from Hydridplastics, 1.48 g, 1.12 mmol) and the thermal inhibitor Butylated HydroxyToluene (BHT, 5.0 mg), were placed in a beaker. The mixture was dissolved hot with magnetic stirring. Stirring was continued until the solution became homogeneous. The thermochromic / POSS@octa(acrylate) assembly was gradually added to the aqueous solution of the surfactant prepared beforehand (40 g, PVA 2% by mass); the mixture was homogenized using an Ultraturrax™ IKA T10 to form an emulsion.

(ii) Microencapsulation

In a reactor, the previously prepared emulsion was introduced. The solution of hexamethylene diamine (HMDA, 0.35 g, 3.01 mmol) in water was added drop by drop using a syringe and with stirring. The reaction was carried out at 50°C for 1 hour and at 80°C for 23 hours.

Figure 13 shows a ce photograph of the microcapsules. Preparation of thermochromic microcapsules based on the monomer

POSS@octa(acrylate) with meta-xylylenediamine

(i) Preparation of the emulsion

10.0 g of thermochromic, and polyoctahedral silsesquioxanes carried from eight acrylate functions (POSS@octa(acrylate), CAS No. 1620202-27-8, purchased from Hydridplastics, 1.50 g, 1.12 mmol) and the thermal inhibitor Butylated HydroxyToluene (BHT, 5.0 mg), were placed in a beaker. The mixture was dissolved hot with magnetic stirring. Stirring was continued until the solution became homogeneous. The thermochromic / POSS@octa(acrylate) assembly was gradually added to the aqueous solution of the surfactant prepared beforehand (40 g, PVA 2% by weight); the mixture was homogenized using an Ultraturrax™ IKA T10 to form an emulsion.

(ii) Microencapsulation

In a reactor, the emulsion prepared previously was introduced. The solution of meta-xylylenediamine (CAS RN 1477-55-0, 0.60 g, 3.01 mmol) in 3 mL of water was added dropwise using a syringe and with stirring. . The reaction was carried out at 65°C for 1 hour and at 80°C for 17 hours. Preparation of thermochromic microcapsules based on the monomer

POSS@octa(acrylate) with POSS@octammonium and hexamethylene diamine (HDMA)

(i) Preparation of the emulsion

10.0 g of thermochromic, and polyoctahedral silsesquioxanes carried from eight acrylate functions (POSS@octa(acrylate), CAS No. 1620202-27-8, purchased from Hydridplastics, 1.40 g, 1.06 mmol) and the thermal inhibitor Butylated HydroxyToluene (BHT, 5.0 mg), were placed in a beaker. The mixture was dissolved hot with magnetic stirring. Stirring was continued until the solution became homogeneous. The thermochromic / POSS@octa(acrylate) assembly was gradually added to the aqueous solution of the surfactant prepared beforehand (40 g, PVA 2% by weight); the mixture was homogenized using an Ultraturrax™ IKA T10 to form an emulsion.

(ii) Microencapsulation

In a reactor, the emulsion prepared previously was introduced. After, the solution of Hexamethylene diamine (HMDA, 0.70 g, 6.02 mmol), POSS@(octa)ammonium (CAS no. 150380-11-3, purchased from Hydridplastics, 0.30 g, 0.26 mmol ), and potassium carbonate (0.16 g, 1.16 mmol) in water was added dropwise using a syringe, with stirring. The reaction was carried out at 65°C for 1 hour and at 80°C for 17 hours. Figure 14 shows a photograph of these microcapsules. Example 14: Biodegradation test

A batch of microcapsules prepared according to Example 8 was supplied. The dry microcapsules but containing essential oil (Eucalyptus) were subjected to the biodegradability test described in document OECD 301 ("OECD Guideline for the Testing of Chemicals: Easy Biodegradability") using the method 301 F (Manometric respirometry test). After an incubation period of nineteen days the percentage of biodegradation was 83%.

Figure 15 shows the evolution of the percentage of biodegradation as a function of time, over a period of 19 days. Curve (b) corresponds to the microcapsule, while curve (a) corresponds to a reference product (sodium acetate) treated separately under the same biodegradation conditions.

Example 15: Biodegradation test

A batch of microcapsules prepared according to Example 8 was supplied. The microcapsules were opened, emptied and washed. They were then subjected to the biodegradability test described in the OECD 301 document (“OECD Guideline for the Testing of Chemicals: Easy Biodegradability”) using the 301 F method (Manometric respirometry test). After an incubation period of twenty-eight days the percentage of biodegradation was 93%.

Figure 16 shows the evolution of the percentage of biodegradation as a function of time.

Example 16: Preparation of scented microcapsules based on a multiamine (Pentaethylenehexamine)

(i) Preparation of the emulsion

19.7 g of essential oil (Eucalyptus) were placed in a beaker, and the multi acrylate monomer (Dipentaerythritol penta-/hexa-acrylate mixture) (1.2 g, 2.29 mmol) was dispersed in the essential oil with magnetic stirring (350 rpm) at 50°C. Stirring was continued until the solution became homogeneous. The essential oil/organic monomer combination was gradually added to the aqueous solution of the surfactant prepared (31.7 g, PVA 2% by weight) previously heated to 50°C; the mixture was homogenized using an Ultraturrax™ IKA T10 at 11500 rpm for 3 min at 50°C to form an emulsion.

(ii) Microencapsulation

In a double-walled reactor, equipped with a mechanical stirring system with IKA blades, preheated to 50° C., the emulsion prepared previously was introduced and stirred at a speed of 250 rpm. Multiamine solution (Pentaethylenehexamine) (1.9 g, 8.00 mmol) in 5.5 g of 2 wt% PVA solution was added dropwise using a syringe and with stirring (250 rpm). The reaction mixture was maintained under stirring for 2 hours at 50°C then 5 hours at 60°C. The total amount of monomers used was 3.1 g. The amine was used in excess relative to the acrylate monomer so as to have an Amine/acrylate molar ratio=3.5. The essential oil/water mass ratio is equal to 0.53. Preparation of scented microcapsules based on an aromatic diamine

(m-xylylene diamine)

(i) Preparation of the emulsion

22.0 g of perfume were placed in a beaker, and the multi acrylate monomer (Dipentaerythritol penta-/hexa-acrylate mixture) (1.52 g, 2.90 mmol) was dispersed in the perfume with magnetic stirring (350 rpm) at 50°C. Stirring was continued until the solution became homogeneous. The perfume/organic monomer combination was added gradually to the aqueous solution of the surfactant prepared beforehand (35.0 g, PVA 2% by mass); the mixture was homogenized using an Ultraturrax™ IKA T10 at 11500 rpm for 3 min at 50°C to form an emulsion.

(ii) Microencapsulation

In a double-walled reactor, equipped with an IKA mechanical blade stirring system, preheated to 65°C, the previously prepared emulsion was introduced and stirred at a speed of 250 rpm. When the emulsion reached 65°C, the solution of m-xylylenediamine (0.80 g, 5.88 mmol) in 5.0 g of 2 wt% PVA solution was added dropwise using a syringe and under agitation (248 rpm). The reaction mixture is kept under stirring for 5 hours at 65°C and 1 hour at 80°C.

The total amount of monomers used was 2.3 g. The amine was used in excess relative to the acrylate monomer so as to have a ratio of functions - NH/acrylate=1.6. The perfume/water mass ratio is equal to 0.55.

Figure 17 shows a photograph of these microcapsules. Preparation of scented microcapsules with a cellulose fiber coating

(i) Preparation of the emulsion

22.0 g of perfume was placed in a beaker, and the multi acrylate monomer (Dipentaerythritol penta-/hexa-acrylate mixture) (1.52 g, 2.90 mmol) was dispersed in the perfume with magnetic stirring (350 rpm) at 50°C. Stirring was maintained until the solution became homogeneous. The perfume/organic monomer combination was added gradually to the aqueous solution of the surfactant prepared beforehand (40.0 g, PVA 2% by weight); the mixture was homogenized using an Ultraturrax™ IKA T10 at 11500 rpm for 3 min at 50° C. to form an emulsion.

(ii) Microencapsulation

In a double-walled reactor, equipped with an IKA mechanical blade stirring system, preheated to 65°C, the previously prepared emulsion was introduced and stirred at a speed of 250 rpm. When the emulsion reached 65°C, the solution of m-xylylenediamine (0.80 g, 5.88 mmol) in 5.0 g of 2 wt% PVA solution was added dropwise using a syringe and with stirring (250 rpm). The reaction mixture is kept under stirring for 5 hours at 65°C and 1 hour at 80°C.

The total amount of monomers used was 2.3 g. The amine was used in excess relative to the acrylate monomer so as to have a ratio of functions - NH/acrylate=1.6. The essential oil/water mass ratio is equal to 0.5.

(iii) Cellulose coating

4% by mass of cellulose microfiber (Exilva F 01 -L) was preheated to a temperature of between 65° C. and 70° C. then introduced into the hot slurry with stirring. The mixture is homogenized hot with stirring for 30 min and for 2 h at room temperature.

A cotton fiber grip test was carried out: a cotton fiber was first wetted and then soaked in slurry. After vigorous and careful washing in water to simulate rinsing, the fiber was dried at room temperature.

Figure 18 shows a photograph (image (b)) of a cotton fiber after soaking in a slurry solution and then drying for microcapsules whose surface has been modified. The coating improves the grip of the microcapsules on the cotton fiber, compared to the microcapsules without coating (image (a)). Preparation of microcapsules (brittle type) based on hexamethylenediamine and dipentaerythritol penta/hexa-acrylate

(i) Preparation of the emulsion

In a 250 ml beaker, dipentaerythritol penta-/hexa-acrylate (2.9 g) (CAS No. 60506-81-2) was dispersed with magnetic stirring (350 rpm) at 50°C in a perfume (80. 0g). Stirring was maintained until the solution became homogeneous (solution "A"). Solution "A" was added gradually in a beaker containing the aqueous solution of surfactant prepared beforehand (105.5 g of PVA (8-88) at 2.0% by weight). The mixture was homogenized using a HOMOMIXER at 5000 rpm for 3 min at 50°C to form an emulsion.

(ii) Microencapsulation

This beaker containing the emulsion was placed in a water bath heated to 50°C, and the emulsion was placed under mechanical stirring with IKA blades (250 rpm). The solution of hexametylenediamine (CAS No: 124-09-4) (1.3 g) in a 2.0% by weight PVA solution (18.2 g) was added dropwise using a separatory funnel. Solution “B” composed of microcapsules at the start of polymerization is obtained. Solution B was left stirring at 50°C for 18 hours; cooling was done with stirring at room temperature.

These microcapsules are of the fragile type.

Example 20:

POSS: Preparation of microcapsules (unbreakable type) based on meta-xylylenediamine and Polyhedral Oligomeric Silsesquioxane (POSS®)

(i) Preparation of the emulsion

In a beaker, the Polyhedral Oligomeric Silsesquioxane (6.0 g) was dispersed with magnetic stirring (350 rpm) at 50° C. in the perfume (36.1 g). Stirring was maintained until the solution became homogeneous (solution “A”). Solution A was gradually added to a beaker containing the previously prepared aqueous surfactant solution (144.3 g, PVA (8-88) at 2.0% by weight). The mixture was homogenized using a HOMOMIXER at a speed of 5000 rpm for 3 min and at a temperature of 50°C to form an emulsion.

(ii) Microencapsulation

This beaker containing the emulsion was placed in a water bath heated to 50°C, and the emulsion was placed under mechanical stirring with IKA blades (250 rpm). The solution of meta-xylylenediamine (CAS No: 1477-55-0) (2.5 g) in deionized water (10.8 g) was added dropwise using an ampule to decanted. Solution “B” composed of microcapsules at the start of polymerization is obtained. Solution B was left stirring at a temperature of 50°C for 1 hour then 65°C for 5 hours. Cooling was done with stirring at room temperature.

These microcapsules are of the unbreakable type.

Example 21: Preparation of PBAE microcapsules with temperature cycling (i) Preparation of the emulsion

1140.5 g of perfume was placed in a beaker, and the multi acrylate monomer (Dipentaerythritol penta-/hexa-acrylate mixture) (67.9 g) was dispersed in the perfume with stirring at 50°C. Stirring was continued until the solution became homogeneous. This solution was added gradually to an aqueous solution of the surfactant prepared beforehand (2073.7 g, PVA 2% by weight); the mixture was homogenized using a Homomixer at 4000 rpm for 3 min at 50°C to form an emulsion.

(ii) Microencapsulation

In a double-walled reactor, equipped with a mechanical stirring system with IKA blades, preheated to 50° C., the emulsion prepared previously was introduced and stirred at a speed of 550 rpm. The solution of meta-xylylenediamine (31.11 g) in 259.21 g of PVA solution (2% by weight) was added dropwise and with stirring. The reaction mixture is kept under stirring for 1 hour at 50°C, 4 hours at 65°C and 1 hour at 80°C. Preparation of scented microcapsules coated with the amino acid derivative N-acetylglycine and cellulose fiber (“soft” version)

The reaction mixture (slurry) obtained according to Example 21 was left to stand at ambient temperature for 24 h. A quantity of 1000 g of this slurry was introduced into a reactor equipped with an IKA mechanical blade stirring system. Then the slurry was heated to 75°C and stirred at a speed of 550 rpm. When the slurry had reached 75° C., a solution at 95° C. of a mixture of N-acetylglycine (10 g) in a previously prepared 2 wt% PVA solution (50 g) was added thereto with stirring. The reaction mixture was allowed to stir for 5 min at 75°C, then allowed to cool to 50°C with stirring. Then, 187 g of cellulose microfiber (Exilva F 01 -L) was preheated to 50° C. and then introduced into the slurry with stirring. The mixture was homogenized at 50° C. with stirring for 30 min at 50° C., then for 2 h at room temperature. Preparation of scented microcapsules coated with the amino acid derivative N-acetylglycine and cellulose fiber (“Medium” version)

The slurry obtained according to Example 21 was left to stand at room temperature for 24 hours. A quantity of 206 g of this slurry was introduced into a reactor equipped with an IKA mechanical blade stirring system. Then the slurry was heated to 75°C and stirred at a speed of 550 rpm. When the slurry had reached 75°C, a solution at 95°C of a mixture of N-acetylglycine (2.6 g) in a previously prepared 2 wt% PVA solution (11.8 g) was poured into it with stirring (550 rpm ). The reaction mixture was allowed to stir for 5 min at 75°C, then allowed to cool to 50°C with stirring. Then, 38.8 g of cellulose microfiber (Exilva F 01-L) was preheated to 50° C. and then introduced into the slurry with stirring. The mixture was homogenized at 50° C. with stirring for 30 min at 50° C., then for 2 h at room temperature.

Example 24: Preparation of scented microcapsules with a coating with the derivative of the amino acid N-acetylglycine and the cellulose fiber (“Hard” version)

The slurry obtained according to Example 21 was left to stand at room temperature for 24 hours. A quantity of 1000 g of this slurry was introduced into a reactor equipped with an IKA mechanical blade stirring system. Then the slurry was heated to 75°C and stirred at a speed of 550 rpm. When the slurry had reached 75°C, a solution at 95°C of N-acetylglycine (15 g) in PVA solution (75 g, 2% by weight) previously prepared was poured into it with stirring (550 rpm). The reaction mixture was allowed to stir for 5 min at 75°C, then allowed to cool to 50°C with stirring. Then, 192.3 g of cellulose microfiber (Exilva F 01-L) was preheated to 50° C. and then introduced into the slurry with stirring. The mixture was homogenized at 50° C. with stirring for 30 min at 50° C., then for 2 h at room temperature.

Table 1 below summarizes the mechanical properties of microcapsules obtained according to Examples 22, 23 and 24.

Table 1: Mechanical properties of rupture of scented microcapsules coated with amino acid derivative N-acetylglycine and cellulose fiber : Preparation of scented microcapsules with a coating of N-acetylglycine, alginate and cellulose fiber

The microcapsule slurry was synthesized as described in Example 21, replacing meta-xylylenediamine with hexamethylene diamine. It was left to stand at room temperature for 24 h. A quantity of 40 g of this slurry was introduced into a reactor equipped with an IKA mechanical blade stirring system. Then the slurry was heated to 75°C and stirred at a speed of 550 rpm. When the slurry reached 75°C, a solution at 95°C of a mixture of N-acetylglycine (0.4 g) in water (2.5 g) previously prepared was added to it with stirring (550 rpm). The reaction mixture was allowed to stir for 2 min at 75°C. Then, sodium alginate (0.12 g) was added, and the reaction mixture was cooled to 40°C with stirring. Then, the cellulose microfiber (4 g, Exilva F 01-L) was introduced into the reaction reactor and allowed to stir for 30 min. Finally, a solution of calcium chloride (0.4 g) in water was added to the slurry. The mixture was homogenized at 40°C with stirring for 30 min at 40°C and for 2 h at room temperature.

Examples 26 to 29 which follow relate to microcapsules whose outer wall has been modified by various means: radical polymerization (example 26), thermal polymerization in the presence of an initiator (example 27), photopolymerization (example 28) or quaternization ( example 29) Redox polymerization by potassium persulfate in the presence of iron (II) sulfate

20 g of a flavored slurry were placed in a 100 ml three-necked flask with magnetic stirring at 35°C. This slurry was then degassed with argon for 30 min. In a hemolysis tube, an aqueous solution of potassium persulfate (KPS) was prepared then degassed for 5 min (30 mg of KPS in 1 ml of water). 9 mg of iron (II) sulfate FeSO4 were dissolved in 1 ml of H2O in another hemolysis tube, the solution is then degassed with argon for 5 min.

The KPS solution was removed and added to the slurry dispersion with magnetic stirring at 250 rpm at 35° C., likewise, the FeSO4 solution was added thereto. The reaction mixture was homogenized at 35° C. for 3 h. The capsules were dried and then analyzed by thermogravimetric analysis (TGA), see Figure 21. In order to characterize a given sample, the onset temperature (T _onS et) which indicates the temperature at which mass loss begins was calculated.

We find the following results:

Tonset is 177.5°C for unmodified microcapsules, and 196.6°C for KPS-modified microcapsules. Thermal polymerization in the presence of the lipophilic initiator AIBN

(i) Preparation of the emulsion

In a 60 ml bottle, a solution of essential oil (22 g), the multi acrylate monomer (Dipentaerythritol penta-/hexa-acrylate mixture) (1.52 g) and the liposoluble initiator azobisisobutyronitrile (AIBN, 0.03 g) were mixed and then degassed with argon for 15 min under magnetic stirring at 30°C.

An aqueous solution of PVA (35 g, 2 wt%) was prepared and degassed with argon in a 60 ml flask for 15 min, the two solutions previously prepared and degassed were heated up to 50°C.

The PVA solution was quickly transferred to a beaker then the essential oil solution was added thereto, and the mixture was homogenized using an Ultra-turrax IKA T10 for 3 min at 50°C to form a emulsion. This emulsion was transferred to a double-walled reactor equipped with an IKA mechanical blade stirring system and preheated to 50°C; the emulsion was degassed with argon.

(ii) Microencapsulation

The solution of Hexamethylene diamine (HMDA, 0.5 g) in 5 g of 2 wt% PVA solution was added dropwise using a syringe and with mechanical stirring (250 rpm). The reaction takes place for 1 hour at 50°C and 4 hours at 65°C then 1 hour at 80°C. The mixture was homogenized at 50°C for 1 hour, then at 65°C for 4 hours and at 80°C for 1 hour.

The capsules were dried and then analyzed by thermogravimetric analysis (TGA), see Figure 22. In order to characterize a given sample, the onset temperature (T _onS et) which indicates the temperature at which mass loss begins was calculated.

We find the following results:

Tonset is 177.5°C for unmodified microcapsules, and 187.7°C for AIBN-modified microcapsules.

Example 28: Photopolymerization (i) Preparation of the emulsion In a beaker, 0.015 g of the liposoluble photoinitiator Diphenyl (2,4,6-trimethylbenzoyl) phosphine oxide (TPO) were dissolved in 22 g of essential oil at 30°C for 10 min, the multi acrylate monomer (Dipentaerythritol penta mixture -/hexa-acrylate) (1.52 g) was then added with stirring. The mixture obtained was added gradually to the aqueous solution of the surfactant prepared beforehand (35 g, PVA 2 wt %); the mixture was homogenized using an Ultra turrax™ IKA T10 at 9500 rpm for 3 min at 50° C. to obtain an emulsion.

(ii) Microencapsulation

In a double-walled reactor, equipped with a mechanical stirring system with IKA blades, preheated to 50°C, the previously prepared emulsion was introduced and stirred at a speed of 250 rpm

The solution of Hexamethylene diamine (HMDA, 0.5 g) in 5 g of PVA solution

2 wt% was added dropwise using a syringe and with mechanical stirring (250 rpm) for 1 hour at 50°C, 4 hours at 65° and 1 hour at 80°C

(iii) Light curing

3 ml of microcapsules obtained were placed in a tank then irradiated at 365 nm using the UV lamp for 5 min, at the end of the photopolymerization, the capsules were dried and then analyzed in ATG, see figure 23 .

Tonset is 160.1°C for unmodified microcapsules, and 189.1°C for irradiation-modified microcapsules.

Example 29: Quaternization

50 g of a previously prepared scented microcapsule slurry were placed in a three-necked flask (250 ml). The pH of the slurry was then lowered to 3-4 by adding acrylic acid. The mixture was then degassed with argon for 30 min, with magnetic stirring (300 rpm) at 35°C. An aqueous solution of potassium persulfate (KPS) was prepared; it was degassed for 5 min (65.5 mg of KPS in 2.5 ml of water). 19.4 mg of iron (II) sulfate FeSO4 was dissolved in 2.5 ml of water in another glass vial, and this solution was then degassed with argon for 5 min.

The KPS solution was added to the mixture (slurry+acrylic acid) with magnetic stirring at 300 rpm at 35° C., then the FeSO4 solution was added. The reaction mixture was homogenized at 35° C. for 3 h.

Table 2 gives the classification of the microcapsules resulting from examples 1 to 29. Table 2: Summary of microcapsule properties

Table 3 gives examples of applications that have been tried.

Table 3: Examples of use for different types of microcapsules

We describe some examples of use in great detail below.

Example 30: Use of PBAE microcapsules containing a perfume in a fabric softener This test is aimed at the use of PBAE microcapsules according to the invention as a perfume carrier in a liquid laundry softener product.

Microcapsules according to the invention containing a perfume were prepared, which were separated into three batches:

Batch No. 1: untreated microcapsules;

Lot no. 2: microcapsules reinforced with an “over-coating” process;

Lot no. 3: microcapsules reinforced with a "post-curing" process.

For each batch of microcapsules, 0.3% by weight of a slurry of these microcapsules was incorporated into a standard base dose of fabric softener; this base did not contain perfume (so-called neutral base). Thus we obtained three batches of fabric softener. Fifteen cotton napkins were provided (each forming a square of about 32 cm).

For each batch of fabric softener, five towels were washed in a standard washing machine with a short wash program, after adding a standard dose of a standard type detergent and a dose of this fabric softener containing the slurry. We spun at 1000 rpm, put the towels on a line and left to dry for a day. Then we “caressed” the dry laundry as if we wanted to store it flat. The intensity of the odor was evaluated with a panel of five people, on a scale from 0 (“does not smell”) to 5 (“smells strongly”). The results are summarized in Table 4 below.

Table 4

Example 31: Use of PBAE microcapsules containing phytosanitary products

This test targets the use of PBAE microcapsules according to the invention as an essential oil carrier in a composition intended to be applied to cherries.

This use is to control the cherry fly, Rhagoletis cerasi. It is a diptera which measures 4 to 5 mm in length, possessing a single pair of wings. Its body is black, with a yellow patch on its back. Its wings are translucent, streaked with bands black. It only attacks cherries: in the spring, from the end of April until June, the adult females land on the fruits, pierce the epidermis and lay their eggs there. A fly can lay between 60 and 70 eggs, with only one egg per cherry. The larvae hatch in one to two weeks, and usually settle in the center of the fruit, around the pit. The maggots thrive by consuming the fruit over three weeks to a month. The affected fruits have a small hole, and brown spots appear.

According to the state of the art, cherries are sprayed with a natural pyrethrum-based insecticide (from Tanacetum cinerariifolium), but its effectiveness remains limited, and will disappear after a few days, due to the oxidation of the active ingredients and their weathering in contact with moisture.

The test was done with two cherry branches, identically exposed, with similar fruit density. On the fruits of branch A, a cloud of pyrethrum aerosol was sprayed. On the fruits of branch B, a cloud of an aerosol of “unbreakable” type PBAE microcapsules containing pyrethrum was sprayed.

On branch A, after 12 to 14 days, a small quantity of fruits are observed which are pierced; a week later their number is greater; contaminated fruit contains a maggot. After 25 days, a very large majority of cherries are holed and all harbor one or more worms. Over the same period, on branch B, we observe: after 14 days there are no cherries with holes, after 21 days three cherries with holes (under the leaves closest to the ground), after 25 days two other cherries with holes, near the first three. This may be related to poor manual spreading of the aerosol.

It is concluded that the use of the product according to the invention has a significantly better efficacy. This is due to the better protection of the active product against oxidation and moisture.

Example 32: Use of PBAE microcapsules in deodorant compositions

This test aims to compare a product A, containing microcapsules of the polyurea type containing a deodorant, with a product B, containing PBAE microcapsules of the “fragile” type containing the same deodorant.

A composition comprising product A and a composition comprising product B were prepared. Using a sponge, 0.40 g of each composition was spread on a nonwoven fabric 12 cm×10 cm in size. We used these tissues with a panel of people accustomed to using deodorants to assess the smell, one day after washing the skin, before and after rubbing with the fabric. A rating of 1 to 10 was used (10 being the best rating).

The following results were obtained:

Product A (polyurea): at rest = score 4 out of 10; after rubbing = score 8 out of 10 Product B (PBAE): at rest = score 3 out of 10; after rubbing = score 10 out of 10. This difference is commercially significant.

Example 33: Use of PBAE microcapsules in biocidal compositions

This test aims to compare the action of a product A (composition of pure essential oils) applied in the form of an aerosol, with the action of a product B (60% water, 40% microcapsules according to the invention containing the same composition as product A) applied in the form of an aerosol. The action was evaluated against bed bugs, a species of heteroptera insects of the Cimicidae family. The insects came from a farm, are all of an identical stage of development, and were fed on human blood using an artificial membrane and a Hemotek device. After gorging, they were placed in two Petri dishes with a diameter of 90 mm closed by a fabric cover, at the rate of 15 pins per box. Beforehand, the products A or B were spread on a blotting paper placed at the bottom of the box, and left to dry. The number of dead insects was then recorded after each D-day, for eight days. The results are summarized in Table 5:

It is observed that product B (non-encapsulated) loses its effectiveness after two days, whereas the encapsulated product has an effectiveness which is spread over at least five days (end of the test after having killed all the insects).

Claims

62 CLAIMS

1. Use of microcapsules with a biodegradable wall made of Poly(Beta-Amino Ester), abbreviated as PBAE, containing at least one active substance, in the formulation of products selected from the group formed by: Cosmetic products and care products intended to be applied to the face or body, in particular creams and lotions for the body, creams and lotions for the face, shower gels, bath gels, products with UV filters, self-adaptive make-up products correcting their tint according to ambient solar or electric lighting, said at least one microencapsulated active substance being in particular intended to be released in a controlled and targeted manner, in particular for vectorization in the skin, for stabilization of pigments and/or dyes, for covering of wrinkles. Hair and scalp care products, including shampoos, conditioners, hair dyes. Depilatory waxes, said at least one microencapsulated active substance being preferably selected from the group formed by thermochromic substances and agents for temperature control. Disinfectant and/or deodorant products intended to be applied to the face or body, or to objects in contact with the body, to control or limit or mask body odor or to control or limit or mask body odor objects in contact with the body, said at least one active substance being preferably selected from the group formed by antiperspirants, perfumes, essential oils, fragrances, oils. Cosmetic textiles, intended to come into contact with the skin, said at least one active substance preferably being selected from the group formed by antioxidant products, anti-cellulite products, products capable of stimulating blood circulation, anti-mold products , antimicrobial products, bactericidal products, virucidal products, oils. Pharmaceutical preparations, in particular intended for use orally, nasally, intra-bloodally, rectally or by topical application, for example cutaneous or ocular, said at least one active substance preferably being selected from the principles pharmaceutical actives. Preparations for the care of the teeth and the mouth, said at least one active substance being preferably selected from bactericidal products, enzymes, flavorings, essential oils, sweeteners. 63 Food preparations, said at least one active substance preferably being selected from flavorings, flavor enhancers, vitamins and vitamin preparations, preservatives, nutritional additives, oils. Insecticidal and/or fungicidal and/or repellent and/or anti-moss preparations, intended for use alone or incorporated into products such as phytosanitary products, paints, coatings, textiles, detergents, plastics. Preparations intended for use in the field of agriculture, said at least one active substance preferably being selected from additives for the cultivation of plants and fertilizers. Preparations intended for veterinary, intracorporeal or extracorporeal use, and in particular pharmaceutical preparations, dermatological preparations and coat care preparations, said at least one active substance being preferably selected from pharmaceutical active principles and in particular dewormers and antiparasitics, food additives, perfumes, fragrances. Preparations for the treatment of textile products, textile fibers or footwear, said at least one active substance preferably being selected from biocidal products, repellents, moth repellents, deodorizing products, self-cleaning products, stain-resistant products, antistatic products, self-healing products, self-repairing products, perfumes, fragrances, detergents, softeners. Preparations for the treatment of bedding, in particular mattresses, pillows, sheets, draw sheets, luggage, fabrics and household equipment such as curtains, cushions, furniture, leather objects, said at least one active substance being preference selected from among biocidal products, repellents, moth repellents, anti-mite products, anti-lice products, anti-mosquito products, deodorant products, self-cleaning products, antistatic products, self-healing products, self-repairing products, perfumes, fragrances, detergents, softeners. Preparations for waterproof or water-repellent coatings, intended to be applied in particular to textile surfaces or leather surfaces, said at least one active substance preferably being selected from hydrophobic compounds, in particular fatty compounds or fluorinated compounds. Deodorant and/or disinfectant and/or antifoam and/or antifungal preparations, said at least one active substance preferably being selected from oily, natural or synthetic products. 64 Detergent products. Glues and adhesives. Preparations for coating building materials, preparations for ensuring watertightness and preparations for thermal insulation or for absorbing and restoring thermal energy, said at least one active substance preferably being selected from phase, paints and varnishes, thermal insulation materials, sealing agents, expansion agents. Products for treating floor coverings, said at least one active substance being preferably selected from the group formed by lubricant products, anti-friction products, anti-slip products, detergents, essential oils, fragrances, perfumes, aromas. Paints, varnishes, dyes and inks, in particular inks for transfer printing, screen printing, ink jet printing or electrostatic printing, and preparations for coating or making paper, said at least one active substance preferably being selected from the group formed by dyes, pigments, thermochromic products, photochromic products, perfumes, flavorings, fragrances. Self-repairing compositions intended in particular for use in surface coatings used in paint, varnish, inks, on cement, concrete, wood, and in compositions of polymer materials and composites. Compositions with a fire retardant and fire extinguisher effect, said at least one active substance possibly being chosen in particular from brominated alkanes of general formula C _n H2n+2-xBr _x ..

2. Use according to claim 1, characterized in that said microcapsules were obtained by a process in which:

(a) an aqueous solution of a surfactant, an oily phase comprising said active substance and at least one first monomer X, and a polar phase comprising at least one second monomer Y;

(b) an emulsion of the O/W type is prepared by adding said oily phase to said aqueous solution of the surfactant;

(c) said polar phase is added to said O/W emulsion, to enable a polymer to be obtained by polymerization of said X and Y monomers, said polymer forming the wall of said microcapsules; 65 and in which said first monomer X is preferably selected from (multi)acrylates, and preferably (multi)acrylates of formula X'-(-O(C=O)-CH=CH2)n with n > 4 and where X' represents a molecule on which n acrylate units are grafted, or selected from the group formed by: diacrylates; triacrylates, in particular trimethylolpropane triacrylate, tetraacrylates, pentaacrylates, hexaacrylates, mixtures of these different acrylates of the O[CH ₂ C(CH ₂ OR) ₃ ]2 type where R is H or COCH=CH ₂ ; polymers carrying pendant acrylate functions; functional oligo PBAEs, prepared for example by reacting diacrylate compounds with a functional primary amine and/or a functional secondary diamine; the mixture of different compounds described above.

3. Use according to claim 2, characterized in that said second monomer Y is selected from amines and preferably selected from the group formed by: primary amines R—NH ₂ ; primary diamines of the NH ₂ (CH ₂ ) _n NH ₂ type where n is an integer which can typically be between 1 and 20, and which is preferably 2 or 6; primary diamines having an aromatic core, and preferably meta-xylylene diamine; (multi)primary amines, and preferably tris(2-aminoethyl)amine; (multi)amines containing primary and secondary amine functions, and preferably tetraethylene pentamine; secondary diamines and preferably piperazine; polymers containing primary and or secondary amine functions, and preferably polyethylene imine.

4. Use according to any one of claims 2 to 3, characterized in that the ratio of the reactive functions of said monomers Y (-NH) and X (acrylate) is greater than 1, preferably between 1 and 5, and even more preferably between 1.2 and 3.8.

5. Use according to any one of claims 2 to 4, characterized in that said polymerization of said monomers is carried out with stirring at a temperature between 20°C and 100°C, and preferably between 30°C and 90°C . 66

6. Use according to any one of claims 1 to 5, characterized in that the outer wall of the microcapsules is modified by one of the following ways:

- Deposition of a coating on the surface of the microcapsule, preferably from a polymer dispersed in an aqueous phase, said polymer preferably being selected from polysaccharides, such as cellulose, starch, alginates, chitosan , and their derivatives;

- Addition of a radical initiator in the aqueous phase and/or the oily phase, said radical initiator preferably being selected:

- - In case of addition in the aqueous phase: in the group formed by water-soluble azo compounds, such as 2,2'-Azobis(2-methylpropionamidine) dihydrochloride, and red-ox systems, such as persulphate d ammonium or potassium in combination with potassium metabisulphite;

- - If added to the oily phase: in the group formed by azo compounds, such as azobis-isobutyronitrile and its derivatives, and peroxidic compounds, such as lauroyl peroxide;

- Addition in the aqueous phase of a water-soluble acrylate capable of modifying the surface state of the microcapsules, said acrylate preferably being a water-soluble monofunctional acrylate capable of reacting with the residual amine functions at the surface of the wall of the microcapsules, said water-soluble monofunctional acrylates being preferably selected from the group formed by 2-carboxyethyl acrylate, 2-(dimethylamino)ethyl acrylate, 2-hydroxyethyl acrylate, poly(ethylene glycol) acrylates, the potassium salt of 3-sulfopropyl acrylate.

7. Use according to any one of claims 1 to 6, wherein said microcapsules are characterized by one of the following characteristics or combination of characteristics:

- an indentation force at break greater than 5,000 pN, preferably greater than 6,000 pN, and even more preferably greater than 7,000 pN; these microcapsules being referred to herein as “unbreakable”;

- an indentation force at break of less than 300 pN and preferably a Tg value of less than 33°C, and in this case preferably less than 32°C and even more preferably less than 31°C; preferably by an indentation force at break of less than 250 pN and preferably by a Tg value of less than 32° C., and in this case preferably less than 31° C. and even more preferably less than 30° C.; and even more preferably by an indentation force at break of less than 200 pN and preferably by a Tg value of less than 32°C, and in this case preferably less than 31°C and even more preferably less than 30°C; these microcapsules being referred to herein as “fragile”;

- an indentation force at break between 200 pN and 5,000 pN, and preferably between 300 pN and 5,000 pN, but with a breaking force between 200 pN and 300 pN their Tg value is preferably d at least 33°C, and for the microcapsules with a breaking force greater than 300 pN it is preferable that their Tg value be between 30°C, preferably between 33°C, and 80°C; these microcapsules being referred to herein as “brittle”.

8. Use according to claim 7, in which unbreakable microcapsules are used for the formulation of a product selected from the group formed by:

- preparations for thermal insulation or for absorption and restitution of thermal energy, and preferably such preparations comprising microcapsules containing phase change materials;

- preparations comprising microcapsules containing a thermochromic or photochromic substance, intended in particular to be used in depilatory waxes, packaging of food products to be heated, labels for refrigerated products making it possible to indicate a possible break in the cold chain, coatings allowing the indication of excessive stress or impacts following an accident, wear or misuse, in particular on plastic or composite parts, on mountaineering ropes, technical fabrics or protective helmets.

9. Use according to claim 7, in which fragile microcapsules are used for the formulation of a product selected from the group formed by: compositions for the treatment of the hair and the scalp, cosmetic preparations and care products, and preferably such preparations comprising microcapsules containing pigments or dyes; food preparations, and preferably such preparations comprising microcapsules containing active food products, such as flavorings, flavor enhancers, vitamins, nutritional additives, preservatives; phytosanitary products, paints, coatings, textile products, detergents, plastic materials, products for the surface treatment of wood, and preferably such products comprising microcapsules containing insecticides, repellents, fungicides, anti-moss products, termite treatment products; preparations for agriculture, and preferably such preparations comprising microcapsules containing additives for the cultivation of plants, and/or fertilizers; phytosanitary preparations; pharmaceutical, food or care preparations intended for use in the veterinary field, and preferably such preparations comprising microcapsules containing pharmaceutical or dermatological active principles or active principles for the care of the coat, such as vermifuges, anti-parasites or agents for controlling or limiting odors; compositions for waterproof or water-repellent coatings, in particular intended to be applied to textile surfaces or leather surfaces, and preferably such preparations comprising microcapsules containing hydrophobic compounds, in particular fatty compounds or fluorinated compounds.

10. Use according to claim 7, in which brittle microcapsules are used for the formulation of a product selected from the group formed by: products in which it is desired to be able to cause the release of the active substance by the application of a mechanical pressure or by a chemical modification of the microcapsule which modifies its mechanical properties; preparations for blowing agents, sealants, adhesives or glues; cosmetic and/or dermatological preparations, care products, in particular shower and bath gel products, deodorants and for odor control, and preferably such preparations comprising microcapsules containing dermatological or cosmetic active principles , preparations for coating cosmetic textiles, and preferably such preparations comprising microcapsules containing antioxidant products, anti-cellulite products, products capable of stimulating blood circulation, as well as anti-mould, anti- microbial, bactericidal and virucidal; preparations for treating or coating textile products or textile fibers, in particular technical, and preferably such preparations comprising microcapsules containing detergent, softener, biocide, antistatic, anti-stain products; preparations for coating, treatment or maintenance of floors, and preferably such preparations comprising microcapsules containing products 69 lubricants and/or anti-friction, or anti-slip products, or even essential oils, fragrances, perfumes, and/or flavorings; preparations having a function of fire retardant and extinguisher, and preferably such preparations comprising microcapsules containing brominated alkanes of general formula C _n H2n+2-xBr _x ; preparations for self-repair, in particular for self-repair following an impact, and preferably such preparations comprising microcapsules containing self-repairing products; preparations for coating paper or for incorporating into a preparation for making paper, and in particular scented inks of the scratch & sniff or rub & sniff type, and preferably such preparations comprising microcapsules containing perfumes, aromas, fragrances, thermochromic substances or adhesives; preparations intended for use in the veterinary field for care products, pharmaceutical compositions and food products, and preferably such preparations comprising microcapsules containing products selected from the group formed by vermifuges, anti-parasites, agents for controlling or limiting odors, pharmaceutically active substances, essential oils, fragrances, perfumes, and/or flavorings, which can be used in many products, by mixing into the product or by applying a coating on the product; preparations intended for the field of agriculture; and preferably such preparations comprising microcapsules containing additives for the cultivation of plants and/or fertilizers; preparations for the treatment of bedding, luggage, fabrics and household equipment, in particular curtains, furniture with fabrics, furniture and other leather objects, cushions, and preferably such preparations comprising microcapsules containing biocidal products and/or repellent products, and in particular anti-mite products, anti-lice products, anti-moth products, anti-mosquito products, and/or anti-stain products, perfumes, essential oils, fragrances and/or flavorings; preparations ensuring watertightness, to be applied to solid materials, for example in the building sector, or flexible, and preferably such preparations comprising microcapsules containing sealing agents and/or 'expansion. 70

11. Use according to any one of claims 2 to 5 and 7 to 10, characterized in that the reaction mixture from step (c) is used directly, optionally after adjustment of the pH value.

12. Use according to any one of claims 6 to 10, characterized in that the reaction mixture resulting from said modification reaction is used directly.

13. Use according to any one of claims 2 to 12, characterized in that microcapsules are used after washing and optionally drying.

14. Use according to claim 13, in which the washed microcapsules are used for the formulation of a product selected from the group formed by: pharmaceutical preparations intended for human or veterinary medicine, food preparations, cosmetic products, for dental and oral care, additive preparations for plant cultivation, preparations for coating cosmetic textiles or medical textiles.

15. Method of use, comprising a use according to any one of claims 1 to 14.

16. Method of use according to claim 15, characterized in that it comprises a step in which the microcapsules, preferably in the form of slurry, are incorporated into a liquid, viscous or pasty preparation, said preparation being intended to be used, or used in a subsequent step, as such, so as to enable the microcapsules to fulfill a desired technical function, and/or said preparation being used as a vehicle for applying the microcapsules to another product, in particular to a solid product, for deploy a sought-after technical function there.

17. Product resulting from the use or from a method of use, of microcapsules with a biodegradable Poly(Beta-Amino Ester) wall containing at least one active substance, according to any one of claims 1 to 15.