FR2960244A1 - Polysaccharide fibers, optionally in the form of textile or non-woven comprise nanoparticles which are covalently grafted by click chemistry on the surface of the fibers, where the nanoparticles comprise an outer envelope of polysiloxane - Google Patents

Abstract

Polysaccharide fibers (I), optionally in the form of a textile or non-woven comprise nanoparticles which are covalently grafted by click chemistry on the surface of the fibers, where the nanoparticles comprise an outer envelope of polysiloxane. Independent claims are included for: (1) producing polysaccharide fibers comprising reacting, according to cycloaddition mechanism, either fibers or polysaccharide-bearing reactive functional group of formula (-CC-X) with nanoparticles carrying reactive azide functions (-N 3) or fibers or polysaccharide-bearing reactive azide functions (-N 3) with nanoparticles bearing reactive functional group of formula (-CC-X) to obtain a covalent bond between the polysaccharide fibers and nanoparticles by click chemistry; and (2) nanoparticles comprising an outer envelope of polysiloxane bearing reactive azide functions (-N 3) or reactive functional group of formula (-CC-X). X : N or CH.

Description

The present invention relates to the technical field of polysaccharide fibers, especially used in the textile industry. It is often desired to modify the properties of polysaccharide fibers, depending on the intended applications, in particular to improve their appearance, their feel, their UV protection capacity or fight bacteria, their anti-fouling function or to allow their traceability. The functionalization techniques used in the field of textiles make use of treatment processes which can be classified in two categories: on the one hand the processes implementing processes of finishing by dipping, coating or any other means comparable to an impregnation. These processes do not require any chemical modification of the constituents, any more than the presence of a new covalent bond, on the other hand, processes using chemical grafting means of chemical compounds making it possible to obtain the desired properties. The chemical functionalizations have been implemented, in a limited way, essentially by grafting of molecules of low molar mass.

The functionalization of polysaccharide fibers with more complex chemical structures, of nanoparticle type in particular, is generally carried out by physical and / or chemical (for example, impregnation) sorption on the textile fibers and not by chemical grafting. In this context, one of the main objectives of the invention is to provide polysaccharide fibers that are functionalized to exhibit advantageous properties, for example in terms of color, impact, bacteriostatic properties, antifouling, anti-pollutant, fluorescent properties or luminescent, magnetic and electromagnetic shielding, protection against UV, thermal emissivity or others, and this in a long-lasting manner, so that these properties are not impaired by washing sessions in particular.

Moreover, the functionalized polysaccharide fibers according to the invention must be obtained easily and economically on an industrial scale and this, using procedures conventionally used.

In this context, the present invention relates to polysaccharide fibers, optionally in the form of a textile or a nonwoven, on the surface of which nanoparticles comprising an outer polysiloxane envelope are covalently grafted with " click chemistry ».

Such a grafting allows a permanent functionalization of the polysaccharide fibers thanks to a non-hydrolyzable and thermostable covalent bond. In particular, in the context of the invention, the bond between the polysaccharide fibers and the nanoparticles is, in particular, achieved by means of a connecting ball comprising a triazole or tetrazole group, for example of formula (A) or (B) N is N, N (A) (B) wherein Z is N or CH, for example 1,2,3-triazole, grafted to a silicon atom of the polysiloxane shell. , Possibly via a spacer arm. In the context of the invention, "nanoparticles" means solid particles at 25 ° C. Such nanoparticles may be homogeneous or be composed of a solid core, surrounded by one or more coating layers. These nanoparticles have a nanometric size. In the context of the invention, nanoscale size means that the largest size of the nanoparticles is in the range of 2 nm to 1 micron, preferably in the range of 50 to 500 nm. This size can, for example, be determined by transmission electron microscopy. These particles may be ovoid, stick-shaped or essentially spherical, so that their larger size corresponds to their diameter. The particles according to the invention comprise a polysiloxane coating. The polysiloxanes or silicones are polymers formed of a silicon-oxygen ... Si-O-Si-O-Si-O-chain and carrying side groups on the silicon atoms. The most common type is linear polydimethylsiloxane or PDMS. The polysiloxane chains can also be branched or constitute three-dimensional networks in which each constituent unit is connected to each of the other units and to the limits of the macroscopic phase by several paths through the macromolecule, the number of paths increasing with the average number of links. concerned. Some silicon atoms, located at the boundaries of the macroscopic phase, are functionalized by an organic spacer so as to ensure the connection by "click chemistry" with the nanoparticles. It is also possible for a portion of the silicon atoms to carry reactive functions or small organic molecules as detailed in the following description. According to a particular embodiment, at least 1% by weight, and preferably more than 10% by weight, of the nanoparticles consists of polysiloxane. According to a preferred embodiment of the invention, the nanoparticles bound to the polysaccharide fibers act as vehicles or even as reservoirs for an active agent. In this case, the nanoparticles comprise, within them, at least one active agent: the active agent can be located inside the nanoparticle and / or at the surface of the nanoparticle. The fact of using nanoparticles according to the invention makes it possible to have a large quantity of active agent, especially in comparison with the fibers of the prior art in which the active agent was directly bound to the surface. Advantageously, the active agent represents between 5 and 80% by weight, preferably between 20 and 50% by weight of the nanoparticle. Preferably, the active agent is not present on the surface of the nanoparticle, but incorporated inside the latter. In this case, the active agent will be incorporated in the core of the nanoparticle and in no way grafted onto the surface of the polysiloxane shell. Any type of active agent may be incorporated into the nanoparticles, and in particular one or more active agents of interest in the field of textiles, such as antibacterial agents, fluorescent or luminescent agents or molecules, agents anti-fouling or anti-pollutants, magnetic agents and optical filters. As examples of antibacterial agents, mention may be made of compounds based on silver, in ionic or metallic form, zinc oxide, and antibiotics. By way of examples of a fluorescent or luminescent agent or molecule, mention may be made of the derivatives of fluorescein and rhodamine and the rare earths. By way of example of anti-pollutant agents, mention may be made of gold nanoparticles which have a catalytic effect. In particular, in the case where the core of the nanoparticle includes a rare earth, when a conventional luminescence is sought, the nanoparticle may comprise a lanthanide of Eu, Tb, Er, Nd, Yb, Tm type; when a luminescence in the infrared is sought, the nanoparticle may comprise an Nd or Yb type lanthanide; when an antistoke luminescence is desired, the nanoparticle may comprise an Er type lanthanide. As a magnetic agent, mention may be made of Co, gadolinium oxide or ferrites. By way of examples of optical filters, mention may be made of silver, gold, titanium dioxide, zinc dioxide, cerium oxide in the form of submicron nanoparticles, in particular of size 10 to 500 nm.

The nanoparticle may consist exclusively of the active agent forming the core of the nanoparticle and the polysiloxane coating. This is particularly the case when the active agent is titanium dioxide or zinc, cobalt or a rare earth sesquioxide which has luminescent or electro-magnetic properties (in the case of Gd and Nd, in particular) of interest . The nanoparticles may comprise a core consisting of a metal 0 or metal oxide nanoparticle surrounded by an outer shell of polysiloxane. By way of example of metal 0, mention may be made of silver, gold, copper, nickel and cobalt. By way of example of a metal oxide, mention may be made of titanium dioxide, zinc dioxide, rare earth oxides or sesquioxides (in particular of Scandium, of tetraium or of an element of the series of lanthanides chosen from Ce, Pr, Nd, Pm, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb and Lu). By way of example of such nanoparticles, mention may be made of titanium dioxide nanoparticles coated with polysiloxane or polysiloxane-coated rare earth sesquioxide nanoparticles the synthesis of which is described in patent application WO 2005/088314. One can also refer to Synthesis and properties of colloidal lanthanide-doped nanocrystals. M. Haase, K., Riwotzki, H. Meyssamy, A. Kornowki, J. of Alloys and Compounds. 2000,303,191, Synthesis and properties of europium-based phosphors on the nanometer scale: Eu2O3 -, Gd2O3: Eu and Y2O3: Eu / R. Bazzi et al J. Colloid and interface, Science, 2004,273,191 Organic-inorganic nanostructured colloids E. Bourgeat-Lami, 2002,2,1, How gold particles suppress quenching concentration of fluoropllores encapsulated in silica beads M. Martini et al J. Phys Chem C. 2009, 113,17669-16677 and Multifunctional nanoparticles : From the detection of biomolecules to therapy, S. Roux et al., J. Nanotechnol, 2010.

In some cases, especially when the active agent is organic in nature or is gold, interesting for its anti-pollutant activity or money of interest for its bacteriostatic activity, in particular, it may also be distributed in a matrix constituting the heart of the nanoparticle. This matrix will be in particular metal oxide, for example silica. It is also possible to use a nanoparticle consisting exclusively of a rare earth sesquioxide core doped with another rare earth of interest, coated with a polysiloxane envelope. The nanoparticles may also contain no active agent, no more at the surface than inside. In fact, certain nanoparticles, as such, such as polysiloxane-coated silica nanoparticles, are of interest in giving the polysaccharide fibers a pleasant feel.

In most cases, the nanoparticles will have on the surface residual functions used for their grafting by click chemistry. It is also possible to "neutralize" the residual functions by a small molecule. It is possible to use a characteristic derivative that is easily dosable by UV (aromatic) or IR (carboxylic ester such as methyl propargylate) making it possible to quantify the number of residual functions. Insofar as it is a question of "neutralizing" the residual functions, it will be possible to profitably use propargyl alcohol so as to increase the hydrophilicity of the system. It is also possible to use the residual functions for subsequent functionalization by a small molecule providing another function, in order to obtain multifunctional nanoparticles. A fluorescent derivative may for example serve as tracer nanoparticles. It is also possible to obtain multifunctional polysaccharide fibers by grafting different nanoparticles by click-chemistry, each providing a functionality. It is also possible to graft, simultaneously on the polysaccharide fibers, nanoparticles as previously described and molecular entities providing another functionalization. This last approach constitutes a variant of the previous approach which consisted in later functionalizing the nanoparticles via the residual reactive functions and may be interesting insofar as the desired functionality is more difficult to access. For example, in the context of the marking of bacteriostatic textiles, it is possible to use nanoparticles containing silver, ensuring bacteriostatic properties, and a fluorescent molecule such as coumarin azido described by Hafren in Macromol. Rapid Common. 2006, 27, 1362-1366. In the context of the invention, the polysaccharide fibers are, for example, composed of a polysaccharide chosen from celluloses and their derivatives and starches and their derivatives. In particular, the natural cellulosic fibers will be used: cotton or, advantageously, linen, hemp, jute, as well as artificial cellulosic fibers of regenerated cellulose: viscoses (standard viscose, Lenpur viscose, bamboo viscose, modal, cupro, lyocell), as well as cellulose acetate fibers. The amount of nanoparticles grafted on the surface of the fibers is very variable and will depend, in particular, on the intended application and, if an active agent is present, the amount of active agent that each nanoparticle will contain. Given the potential significant content of active principle contained in the nanoparticles, a small amount of grafted nanoparticles may lead, in some cases, interesting properties. It is therefore not necessary to consider high degrees of substitution.

The degree of substitution (DS) can be defined as the number of modified alcohol functions per anhydroglucose unit of the polysaccharide. The maximum theoretical DS is 3. For example, fibers having a DS of 1, on which nanoparticles containing silver have been grafted, have notable bacteriostatic properties.

The polysaccharide fibers may be in an individual form or in the form of a fabric or nonwoven for textile and biomedical applications in particular. The subject of the present invention is also a process for preparing polysaccharide fibers according to one of the preceding claims, in which the reaction is carried out according to a cycloaddition mechanism.

or polysaccharide fibers carrying reactive functions -CX with X = N or CH with nanoparticles carrying reactive functions -N3, or polysaccharide fibers carrying reactive functions -N3 with nanoparticles carrying reactive functions -C = X with X = N or CH, so as to obtain by "click chemistry" a covalent bond between the polysaccharide fibers and the nanoparticles.

Such a method has many advantages, in particular because of its simplicity, its respect for the environment and its low cost.

The chemical binding mechanism called "click chemistry" (or click chemistry) or Huisgen reaction has been described for the first time by Huisgen and Szeimies in Chem. Ber. 1967, 100, 2494 and Ber. 1965, 98, 4014. These publications describe a 1,3-dipolar cycloaddition reaction of an azido derivative on an alkyne derivative at high temperature, according to the scheme below: + N = N-N-R + R 'R'

The contribution of copper (I) catalysis to control the regioselectivity of the cycloaddition between an alkyne derivative and an azide derivative has been clearly established by Sharpless (Kolb, M., M. Finn, K. Sharpless, Angew, Chem. Int Ed (2001), 40, 2004) and will be advantageously used in the context of the invention. The use of "click-chemistry" for binding molecules to polysaccharide entities has already been described in the literature. In particular, mention may be made of WO 2009/063082 which describes hybrid compounds comprising a polysaccharide part to which a polymer of the polyoxyalkylene type is linked by "click chemistry". In the context of the invention, polysaccharide fibers carrying reactive functions -N3 or -C = X with X = N or CH are used. For this, at least a part of the saccharide units constituting the polysaccharide have at least part of their hydroxyl functions which is substituted by such a reactive function. This functionalization can take place at any carbon of the saccharide entities, anomers or not. Advantageously, the process according to the invention does not require protection of the sensitive groups carried by the alcohol functions located on the saccharide carbons whatever they are. The preparation of polysaccharide fibers carrying reactive functions -C = -X with X = N or CH may be carried out as described in the patent application WO2009 / 063082 to which reference may be made for R more details. The functionalization of the hydroxyl groups of the polysaccharides by reactive functions -C = X with X = N or CH can be carried out either directly or via a divalent L1 bond, acting as a spacer arm, of the alkylene type in particular (-CH2) n- or oxyalkylene, especially - (CH2CH2-0) n- with n which is an integer capable of taking the values from 1 to 12. The polysaccharide fibers carrying reactive functions -CX with X = N or CH are, for example, obtained by reacting an alkenyl precursor comprising at least one halogeno group (for example bromo) such as propargyl bromide with at least one OH function of the polysaccharide. In the case where the substitution takes place on the anomeric carbon of the polysaccharide, is reacted, for example, an alkenyl precursor comprising at least one amino group (for example terminal) with the anomeric carbon of the polysaccharide. The preparation of polysaccharide fibers carrying reactive functions -N3 may be carried out as described in the patent application WO2009 / 063082 to which reference may be made for more details. The functionalization of the hydroxyl groups of the polysaccharides by reactive functions -N3 can be carried out either directly or via a divalent L2 bond, acting as a spacer arm, of the alkylene type in particular - (CH2) m- or oxyalkylene , in particular - (CH2CH2-0) m - with m which is an integer capable of taking the values from 1 to 12. The polysaccharide fibers carrying reactive functions -N3 are, for example, obtained by reacting a brominated precursor or tosylate by example CBr4, mesityl chloride or paratoluene-sulfonyl chloride with the primary OH polysaccharide .. The methods described in Macromol rapid Commun. 2006 27, p 208-213 (Tosylation and then substitution with NaN3) and Journal of the American Chemical Society, v 129, n 13, Apr 4, 2007, p 3979-3988 (bromination and substitution with NaN3) can also be implemented .

The nanoparticles carrying reactive functions -N3 or -C-X with X = N or CH, used to carry out the "click chemistry" reaction are new and form an integral part of the invention. Also, the present invention also relates to nanoparticles comprising an outer polysiloxane envelope carrying reactive functions -N3 or -C = X with X = N or CH. The polysiloxane envelope allows the functionalization of the nanoparticles with the reactive functions necessary for their subsequent fixation by "click chemistry" on the polysaccharide fibers. In particular, the reactive functions -N3 or -C. = X with X = N or CH are directly bonded or, indirectly via a spacer arm, to a silicon atom. Advantageously, the number of reactive functions represents 0.01 to 10% of the number of silicon atoms present in the polysiloxane envelope. Their preparation is carried out according to methods similar to those previously described for the preparation of reactive functional polysaccharide fibers. In the case of nanoparticles carrying reactive functions -N3, the methods described in Macromol Rapid Commun. 2006 27, p 208-213 (Tosylation and then substitution with NaN3) and Journal of the American Chemical Society, v 129, n 13, Apr 4, 2007, p 3979-3988 (bromination then substitution with NaN3) will, for example, be used . A polysiloxane layer carrying reactive functional groups -NH 2 is firstly produced, for example by reaction of (TEOS) and (APTES). These reactive functions -NH2 are then converted into bromide, which leads to an azido function by reaction with NaN3. In the case of nanoparticles carrying reactive functions -CX with X = N or CH, the polysiloxane layer carrying reactive functions can be obtained. starting from the same nanoparticles carrying NH2 function, then amidification with undecynoic acid or propargyl chloroformate. It is also possible to envisage the coupling with undecanol via succinic anhydride or to envisage the direct use of triethoxysilane precursors carrying the alkyne function. The "click chemistry" reaction between the nanoparticles thus functionalized and the functionalized fibers with a function, called complementary function, implements a cycloaddition reaction which is carried out in the presence of a copper I catalyst, preferably in an aqueous medium, hydroorganic or organic, in accordance with conventional conditions for implementing a "click chemistry" reaction. Preferably, such a reaction is carried out in the presence of at least one metal catalyst in ionized form, preferably Cul +, in the presence of at least one Cu + Cu + reducing agent, in situ. By way of examples of such reducing agents, mention may be made of ascorbate, quinones, hydroquinones, vitamin KI, glutathione, cysteine, Fe2 + or Col + ions, Cu, Al, Be, Co, Cr metals. , Fe, Mg, Mn, Ni, and Zn. A catalyst, of the copper sulfate type, preferably comprising at least one activator comprising, for example, at least one salt of organic acid (s) (ideally ascorbic acid) and at least one alkaline metal (ideally Na), such as CuSO4 / sodium ascorbate is, for example, quite suitable. The process according to the invention can be carried out under mild conditions. The "click chemistry" reaction is preferably carried out at a temperature of 20 to 100 ° C., preferably of 50 to 80 ° C., for 0.1 to 20 hours, preferably for 0.5 to 15 hours. and more preferably for 1 to 8 hours. The heating of the reaction mixture can be carried out by any suitable means. Microwave irradiation can be an interesting heating modality. The "click chemistry" reaction may be carried out in an aqueous, hydroorganic, especially aqueous or organic medium preferably comprising at least one solvent chosen from: - aprotic polar solvents, preferably dimethyl sulfoxide (DMSO), dimethylformamide (DMF) DiethylAcetamide (DMAc), tetrahydrofuran (THF), acetone, methyl ethyl ketone, butanone; protic polar solvents, preferably methanol, isopropyl alcohol (IPA), t-butanol (t-BuOH), apolar solvents, preferably toluene, hexane, xylene, water , and their mixtures.

Preferably, the solvent or mixture of solvents used will be chosen for its ability to disperse the nanoparticles reacted and / or swell the fibers reacted in accordance with the conventional conditions for carrying out a "click chemistry" reaction.

The process being carried out in a heterogeneous phase, in the end, the recovery of the functionalized fibers is easy and is carried out by simple separation, in particular by filtration, optionally followed by final evaporation of the residual solvent, to dry the fibers, if necessary. The copper catalyst can also be easily removed by washing. The polysaccharide fibers on the surface of which are covalently grafted by "click chemistry", nanoparticles, are particularly stable in aqueous medium at a pH between 6 and 10. Depending on the grafted nanoparticles, and the possible presence of active principle contained in these nanoparticles, they may have desired properties in various textile applications, such as a pleasant feel or appearance, optical properties, such as coloration, fluorescence or ability to protect against UV, electromagnetic properties , coding properties, vectorization properties of bacteriostatic agents or other active molecules, or any other properties that might be interesting to bring on polysaccharide fibers, especially on a tissue of such fibers. The following examples illustrate the invention but are not limiting in nature.

Examples A) Functionalization of cotton: The cotton used is standard commercial hydrophilic cotton, it is washed with water and a 50/50 water / isopropanol mixture before reaction. After drying in the open air, 250 mg of cotton (OH equivalent: 1.852 moles of OH per 100 g) are dispersed in 20 ml of isopropanol (i-PrOH). After stirring for 10 minutes, 5 ml of an aqueous solution of sodium hydroxide with 6.5% sodium hydroxide solution (0.325 g NaOH) are added dropwise. Everything is left like this for one hour, at room temperature. 1 ml of propargyl bromide is then added dropwise. The reaction is carried out for 24 hours at 60 ° C.

Once the reaction is complete, the medium is neutralized with a 0.05% aqueous solution of acetic acid (pH = 7) and the grafted cotton is filtered on sintered No. 3. Different washes are then carried out with an i-PrOH: H 2 O = 50:50 mixture and then with distilled water. The final product is dried in an oven at 60 ° C. Functionalized cotton with -C ° CH functions is characterized by InfraRed: vibration of -CCN groups at 2119 cm-1 and at 604 cm-1

81) Preparation of Amino Nanoparticles Incorporating FITC Fluorescent Agent (FITC @ SiOx-NHz) into Their Core A fluorescent agent solution is prepared by direct dissolution of FITC (fluorescein isiothiocyanate) in APTES (aminopropyltriethoxysilane) stirring at room temperature so as to have an APTES / FITC molar ratio = 20. A water-in-oil quaternary microemulsion is prepared by mixing: 2.27 mm Triton X-100 (surfactant), 2.31 ml n hexanol (cosurfactant) of 9.61 ml of cyclohexane (oil) and 0.61 ml of water at pH 5.5. After 5 minutes, 0.040 ml of the solution containing the previously obtained fluorescent agent is added to the microemulsion. Then, 0.020 ml of APTES and 0.289 ml of TEOS (tetraethoxysilane) are added. After 30 minutes, the polymerization reaction of the silica is completed by adding 0.173 ml of NH 4 OH and the reaction mixture is stirred for 24 hours. Surface functionalization is obtained by adding 0.200 ml of TEOS and after 30 minutes of 0.100 ml of APTES. The microemulsion is broken by addition of ethanol, followed by vortexing and repeated centrifugation. The average size measured by dynamic light scattering (Malvern Zetasizer apparatus) of FITC @ SiOx-NHz nanoparticles obtained is 80 nm.

B2) Preparation of Amine Nanoparticles Incorporating Into Their Silver Heart (Named Ag @ SiOx-NH2) A quaternary microemulsion w / o is prepared by mixing 2.10 ml of Triton X-100 (surfactant), 2.14 ml n-hexanol (co-surfactant), 8.91 ml of cyclohexane (oil). The aqueous phase consists of a mixture of 0.595 ml of 16.7 mM AgNO 3, 0.595 ml of 32.8 mM of sodium 2-mercaptoethanesulphonate (MES) and 0.198 ml of 412 mM NaBH 4 in order to synthesize the silver nanoparticles. . After 5 min, 0.020 ml of APTES and 0.289 ml of TEOS are added. After 30 min, the polymerization reaction of the silica is completed by the addition of 0.173 ml of NH 4 OH and the reaction mixture is agitated for 24 h. Since the colloidal stability, a protection ("Shell") is synthesized by adding 3 ml of TEOS and after 30 min, 0.6 ml of APTES. The microemulsion is broken by adding ethanol to the microemulsion, followed by vortexing and centrifuged several times. The average size measured by dynamic light scattering (Malvern Zetasizer apparatus) of Ag @ SiOx - NH2 nanoparticles is 50 nm.

C) Functionalization of nanoparticles: The nanoparticles (env 60 mg) prepared in paragraph B1) or B2) carrying amine functions are suspended in dichloromethane. Then 10 μl of triethylamine and 40 μl of 2-bromopropionic acid chloride are added. The reaction mixture is stirred at ambient temperature for 12 hours, then the nanoparticles are precipitated in ethanol. They are recovered by centrifugation at 10,000 rpm for 15 to 20 minutes. Several wash cycles are then performed to remove excess reagents and by-products. The nanoparticles are kept in precipitated, but wet form, to facilitate redispersion. Then, 25 mg of brominated nanoparticles are dispersed in 2 ml of DMF and a spatula tip of NaN3 (about 20 mg) is added. The reaction mixture is stirred at 80 ° C for 24 hours. The nanoparticles obtained are purified by washing with a 0.05% NaHCO3 solution (pH 8), followed by 3 washes with water. Between each wash, the nanoparticles are recovered by centrifugation at 10,000 rpm for 20 minutes.

The nanoparticles obtained are then redispersed, by vortexing, in 2 ml of DMF. After the last wash, the nanoparticles are dispersed in 1 ml of DMF, transferred to an ependorf, and then precipitated at 10,000 rpm for 20 minutes. About 20 mg of nanoparticles carrying N3 functions are recovered.

The brominated FITC @ SiOx nanoparticles have the characteristic IR peaks of the amide group -NH-CO- at 1656 cm -1 and the brominated group at 564 cm -1. The spectrum of the azide-functional particles shows the characteristic peaks of amide groups by -NH-CO- the peak at 1656 cm-1 and by -NH-CO- the peak at 1571 cm-1; and the azide group -N3 the peak at 2036 cm-1. Similarly, the Ag @ SiOx-N3 azide nanoparticles exhibit the characteristic peaks of the amide groups: at 1656 cm -1 and at 1536 cm -1, as well as the signal of azide groups -N3 at 2046 cm-1.

Dl) Click chemistry reaction in organic medium 24 mg of functionalized cotton obtained in paragraph A is suspended in 5 ml of DMSO at 80 ° C. The reaction mixture is stirred for 30 minutes before adding 8 mg of Cul and the nanoparticles obtained in paragraph C) (approximately 20 mg) suspended in 0.5 ml of DMSO. The assembly containing the reaction mixture is then covered with aluminum foil to protect the azide from light and the stirring is maintained at 80 ° C for 24 hours. After 24 hours, after stopping the heating, the reaction mixture is allowed to return to ambient temperature. Then, the cotton and the reaction mixture are poured into 40 ml of ethanol. The magnetic stirring is maintained for 15 minutes then the whole is filtered on sintered. Two further ethanol washes, then a dichloromethane wash and finally a water wash are performed. The product obtained is then dried in an oven at 65 ° C. The single figure represents a scanning electron microscopy photograph of functionalized fibers in organic medium with Ag @ SiOx-N3 azide nanoparticles.

D2) Reaction of click chemistry in hydroalcoholic medium, The grafting takes place in a glass container, under an argon atmosphere. In 20 ml of a water-IprOH mixture (1/1), 105 mg of propargyl cotton are dispersed. After 30 minutes under argon, 42.5 mg (0.17 mmol) of CuSO.sub.4.5H.sub.2 O are added, then, after 15 minutes, 190 mg (1.08 mmol) of ascorbic acid and 0.043 g (1.08 mmol) are added. ) NaOH. Finally, after 30 minutes, the silica particles carrying azide functions are added (the assembly is covered with an aluminum foil to protect the azide from the light). After 24 hours, the cooled medium is neutralized with an aqueous solution of 0.05% sodium hydroxide (pH = 4 at pH = 7) and the grafted cotton is filtered on sintered No. 3. Different washes are then carried out with a mixture of iPOH: H 2 O = 50:50 and then with distilled water. The final product is dried in the oven at 60 ° C. The IR spectrum confirms the grafting on the cotton by decreasing the peak corresponding to the alkyne group (2119 cm-1), the presence of the peaks corresponding to the amide groups (1718 cm-1) and -O-Si-O- ( 1085 cm-1) silica nanoparticles functionalized with azide groups and the presence of peaks corresponding to -C = C-conjugated groups (1540 cm-1) and off-plane deformation -C = CH- (805 cm-1) of triazole rings.

E) Bacteriostatic activity The bacteriostatic activity of the grafted fibers with Ag @ SiOx nanoparticles in accordance with the invention was tested according to a quantitative counting method derived from Standard ISO 22196: 2007 (inoculum prepared in a non-nutritive medium) 1 - Principle The principle is the deposition of a suspension of bacteria, of known concentration, on a piece of the sample to be analyzed. It is left in contact for a pre-established time (24 hours).

After 24 hours, the sample is rinsed with a diluent medium, the viable bacteria are thus recovered and counted: in this way, the anti-bacterial activity of the sample is calculated. 2 - Procedure Bacterial strain used: Staphylococcus aureus ATCC 6538 P 10 (gram +) The cotton sample to be tested is placed at the bottom of a sterile bottle. A known volume (0.1 ml) of inoculum (suspension of bacteria of known concentration) is taken by pipette and then deposited on the sample. The inoculum is prepared in a non-nutritive medium for the standard ISO 22196: 2007. A polyethylene film pellet is then placed on the inoculated sample so that there is good spreading and good contact of the inoculum with the inoculum. sample tested, and also to avoid evaporation of water. The vial containing the inoculated sample is then placed in a controlled incubation chamber: Incubation temperature: 30 ° C. ± 1 ° Relative humidity: 90% * Duration of contact of the bacteria on the sample: 24 hours A After expiration of the contact time, 20 ml of diluent medium is poured into the vial and then vigorous stirring is exerted to remove the bacteria present on the sample. The viable bacteria are then counted by the method of successive dilutions. The Petri dishes are placed in an incubation chamber 30 (Incubation temperature: 30 ° C ± 1). The results are read after a minimum of 48 hours of incubation. 3 - Expression of Results With the ISO 22196: 2007 standard, the Inoculum used is developed in a non-nutritive medium, which prevents any growth of the bacterial population. Under these conditions, the logarithmic regression of the surviving bacterial population is measured. Log UT - Log AT R: anti-bacterial activity (value expressed on a scale of 0 to 5) UT: number of viable bacteria per cm3 for the control inoculum after 24 hours AT: number of viable bacteria per cm3 for the sample tested after 24 hours This test method makes it possible to define the anti-bacterial activity of a material, with an R value of 0 to 5. 0 0 means no activity 5 means a maximum activity (corresponds to a biocidal effect) Sample of cotton functionalized in a hydroalcoholic medium, and washed again with an alkaline solution of sodium hydroxide Bacteria used: Staphylococcus aureus (gram +) Inoculum: 4.106 CFU / ml (after 24 hours of contact a with bacteria): <2.103 CFU Let R? 3.3 (which corresponds at least to a bacteriostatic effect) Sample of cotton functionalized in an organic medium, and washed again with a hydroalcoholic solution: Bacteria used: Staphylococcus aureus 25 (gram +) Inoculum: 3.4.107 CFU / ml After 24 hours of contact: R = 3.4

Claims (19)

CLAIMS1 - Polysaccharide fibers, optionally in the form of a textile or a nonwoven, on the surface of which are grafted covalently by "click chemistry", nanoparticles comprising an outer shell of polysiloxane. 2 - polysaccharide fibers according to claim 1 characterized in that the bond between the fibers and the nanoparticles is achieved by means of a connecting ball comprising a triazole or tetrazole group, in particular of formula (A) or (B) below: Wherein Z is N or CH, said ball being grafted, optionally via a spacer arm, to a silicon atom of the polysiloxane shell. 3 - polysaccharide fibers according to claim 1 or 2 characterized in that at least 1% by weight, and preferably more than 10% by weight of the nanoparticles consist of polysiloxane. 4 - polysaccharide fibers according to one of the preceding claims characterized in that the nanoparticles comprise, within them, at least one active agent. 20 5 - polysaccharide fibers according to claim 4, characterized in that the active agent is chosen from antibacterial agents, fluorescent or luminescent agents or molecules, antifoulants or antipolluting agents, magnetic agents and optical filters. 6 - polysaccharide fibers according to one of the preceding claims 25 characterized in that the nanoparticles comprise a core consisting of a metal nanoparticle 0 or metal oxide surrounded by an outer polysiloxane envelope. 7 - polysaccharide fibers according to one of the preceding claims characterized in that the nanoparticles are nanoparticles of titanium dioxide coated with polysiloxane. 8 - polysaccharide fibers according to one of the preceding claims characterized in that the nanoparticles consist of a silica core, in which is distributed an active agent, and a polysiloxane coating. 9 - polysaccharide fibers according to one of the preceding claims characterized in that the nanoparticles have a size in the range of 2 nm to 1 micron, preferably in the range of 50 to 500 nm. 10 - polysaccharide fibers according to one of the preceding claims characterized in that the polysaccharide fibers are composed of a polysaccharide selected from celluloses and their derivatives and starches and their derivatives. 11 - A method for preparing polysaccharide fibers according to one of the preceding claims wherein is reacted, according to a cycloaddition mechanism - or polysaccharide fibers carrying reactive functions -C = X with X = N or CH with nanoparticles carrying reactive functions - N3, - or polysaccharide fibers carrying reactive functions -N3 with nanoparticles carrying reactive functions -C = X with X = N or CH, so as to obtain by "click chemistry" a covalent bond between the polysaccharide fibers and the nanoparticles. 12 - Process according to claim 11 characterized in that the cycloaddition reaction is conducted in a hydroalcoholic medium. 13 - Nanoparticles comprising an outer shell of polysiloxane carrying reactive functions -N3 or -C- = X with X = N or CH. 30 14 - Nanoparticles according to claim 13 characterized in that they comprise, within them, at least one active agent. Nanoparticles according to claim 14, characterized in that the active agent is chosen from antibacterial agents, fluorescent or luminescent agents or molecules, antifouling or antipolluting agents, magnetic agents and optical filters. 16 - Nanoparticles according to claim 13, 14 or 15 characterized in that they comprise a core consisting of a metal nanoparticle 0 or metal oxide surrounded by an outer shell of polysiloxane. 17 - Nanoparticles according to claim 13, 14 or 15 characterized in that they comprise a core consisting of silica in which is distributed an active agent, surrounded by an outer shell of polysiloxane. 18 - Nanoparticles according to claim 13 characterized in that they correspond to nanoparticles of titanium dioxide coated with polysiloxane. 19 - Nanoparticles according to one of claims 13 to 18 characterized in that the reactive functions -N3 or -C = X with X = N or CH are linked directly or, indirectly via a spacer arm, to a silicon atom. Nanoparticles according to one of Claims 13 to 19, characterized in that the number of reactive functional groups represents from 0.01 to 10% of the number of silicon atoms present in the polysiloxane envelope.