FR3039765A1 - COSMETIC PROCESS FOR TREATING KERATINIC MATERIALS - Google Patents

Abstract

The invention relates to a cosmetic process for treating keratin materials comprising: (i) the application to the keratin materials of a composition comprising a polymer (I): in which R 'independently represents H or an acetyl group or a group - CO-L-SH, the polymer containing at least one group R '= -CO-L-SH, L being a divalent hydrocarbon group comprising from 1 to 20 carbon atoms n varies from 5 to 2000. Application for the treatment of odors human body, to fight against the formation of scalp dandruff, to give hair the softness and / or ease of combing hair.

Description

The present invention relates to a process for treating keratin materials, using a composition comprising a chitosan polymer grafted with a group comprising a thiol function.

In the cosmetic field, chitosan is a film-forming polymer commonly used in particular in hair shaping products. Chitosan is also disclosed in CA-A-2232422 as an anti-dandruff active. Chitosan is also used in deodorant products to reduce or prevent the formation of unpleasant body odors, and more particularly axillary odors as described in particular in US-A-20030133891.

There is therefore still a real need to develop active compounds which have a satisfactory cosmetic activity and which are easy to formulate in compositions intended to reduce perspiration and / or odors, in particular in humans, and more particularly to fight against body odors, and more specifically axillary odors.

The object of the present invention is to provide a cosmetic product comprising a chitosan-based polymer with improved cosmetic properties. In particular, the object of the invention is to optimize the cosmetic properties of chitosan, in particular the deodorant, anti-dandruff, softness and hair removal properties.

As shown by the comparative examples illustrating the present invention, the inventors have found that topical application to keratin materials of a chitosan polymer having thiol functional groups, forms a film.

This film has deodorant properties, anti-dandruff, gives the hair the softness and facilitates their combing. These cosmetic properties are more efficient than those obtained with unmodified chitosan.

The resulting film has good water resistance.

More specifically, the subject of the present invention is a cosmetic process for treating keratin materials, comprising the topical application to the keratin materials of a composition, in particular a cosmetic composition, comprising, in a physiologically acceptable medium, a chitosan polymer whose amino groups are grafted thiol groups of formula (I) as defined below.

The grafted chitosan polymer used in the process according to the invention is a polymer of formula (I):

(I) wherein R 'is independently H or an acetyl group (CH3C (O) -) or a group -CO-L-SH, the polymer containing at least one group R' = -CO-L-SH, L being a divalent hydrocarbon group comprising from 1 to 20 carbon atoms, preferably from 2 to 10 carbon atoms, linear, branched or cyclic, saturated or unsaturated, and capable of being interrupted by one or more non-adjacent heteroatoms chosen from oxygen, sulfur or -NH-, -CO-, -CONH-, -COO-, -O-CO-N (Ra) - groups, in particular -O-CO-NH-, -N (Rb) -CO-N (Rc) -, in particular -NH-CO-NH-, said divalent group possibly being substituted for one or more groups selected from hydroxyl groups, amine -N (Ra) (Rb) (Rc), thiol, carboxylic acid , -C? 2Ra, amide -N (Ra) CO- (Rb), cyano, acyl (C 1 -C 4) amino, ureido -N (Ra) -CO- N (Ra) (Rb) esters with Ra, Rb, , Rc independently denoting a hydrogen atom or a linear or branched C- | -Cq alkyl radical, of p linear reference; n varies from 5 to 2000.

Thus, the grafted chitosan (I) can also be represented according to formula (Ia):

wherein the grafted chitosan comprises free amino-bearing units, N-acetylated amino-bearing units and amino-group-grafted moieties of a -CO-L-SH group; b is from 0 to 0.5, preferably from 0.05 to 0.30, and more preferably from 0.1 to 0.30; c is from 0.001 to 0.5, preferably from 0.01 to 0.3, and more preferably from 0.01 to 0.2; anda + b + c = 1 L and n having the meanings previously described.

For example, when a = 0.5, b = 0.3 and c = 0.2, this means that 50% of the amino groups are free (unsubstituted), 30% of the amino groups are acetylated and 20% of the amino groups are grafted with the -CO-L-SH group corresponding to the chitosan polymer of formula:

Preferably, the grafted chitosan has a degree of grafting (molar rate) in groups (-CO-L-SH) ranging from 0.1 to 50%, preferably ranging from 1 to 30%, and more preferably ranging from 1 to 20%. %.

Preferably, L is a linear, branched or cyclic, saturated or unsaturated C 1 -C 20 hydrocarbon-based divalent C 1 -C 20 hydrocarbon radical, which may be interrupted by one or more non-adjacent heteroatoms. selected from oxygen or one or more non-adjacent groups selected from -NH-, -CO-, -O-CO-, -NH-CO-.

Advantageously, the grafted chitosan (I) has a degree of acetylation (-CO-CH 3) ranging from 0 to 50% (especially from 0.1 to 50%), preferably ranging from 5 to 30%, and more preferably ranging from from 10 to 30%.

Advantageously, n varies from 5 to 1700, preferably from 5 to 280, more preferably from 15 to 165.

Preferably, L denotes a divalent radical chosen from:

* representing the bond with the thiol group; ** representing the bond with the C (O) NH group of chitosan;

Preferably, L denotes the divalent radical

The compounds (I) can be obtained according to a first method of preparation (Scheme 1) by the reaction of a chitosan with a thiolactone (A): the primary amine group of chitosan reacting with the thiolactone function forms an amide compound (I ). This reaction is especially known with homocysteine thiolactone in the publication "Synthesis and characterization of chitosan-homocysteine thiolactone as a mucoadhesive polymer", K. Juntapram et al., Carbohydrate Polymers; 87 (2012) 2399-2408.

(I)

Diagram 1

The reaction can be carried out in an aprotic or protic solvent. Preferably the reaction is carried out in water at a pH of between 4 and 9 and preferably between 5 and 7. The reaction can be carried out at a temperature of between 5 and 80 ° C. Preferably the reaction is carried out at room temperature (25 ° C).

The compounds (I) can also be prepared according to a second method of preparation (scheme 2) by the reaction of a chitosan with a thiolated carboxylic acid (B) to form the amide compound (I). Such a reaction between an amine and a carboxylic acid is known to those skilled in the art and described in publications such as "Catalytic amide formation from non-activated carboxylic acids and amines" Chem. Soc. Rev., 2014, 43, 2714-2742; "Evolution of amide bond formation" ARKIVOC 2010 (viii) 189-250; "Amide bond formation: beyond the myth of coupling reagents" Chem. Soc. Rev., 2009, 38, 606-631.

According to a first alternative of this method of preparation, it is possible to use in place of the compound B a thiolated activated carboxylic acid B '. The reaction is a reaction between a primary amine (that of chitosan) and an activated carboxylic acid (B ') to form an amide. This reaction is known to those skilled in the art and described in numerous journals such as March's Advanced Organic Chemistry: Reactions, Mechanisms, and Structure, 7th Edition (ISBN: 978-0-470-46259-1).

According to a second alternative of this method of preparation, it is possible to use in place of compound B a carboxylic acid (activated or not activated) comprising a protected thiol group (B "), in a first step, the amine group of chitosan reacts with the carboxylic acid to form an amide. then, in a second step, the protected thiol group is released by a deprotection reaction. This deprotection reaction is described in numerous articles such as March's Advanced Organic Chemistry: Reactions, Mechanisms, and Structure, 7th Edition (ISBN: 978-0-470-46259-1), Protecting groups, J. Chem. Soc., Perkin Trans. 1, 1999, 1589-1615 and Protecting groups, J. Chem. Soc., Perkin Trans. 1, 1998, 4005.

Figure 2

The reaction between chitosan and the compound (B) or (B ') or (B ") can be done directly in an aprotic or protic solvent. Preferably the reaction is carried out in water at a pH between 4 and 9 and preferably between 5 and 7. The reaction is carried out at a temperature of between 5 and 80 ° C. Preferably the reaction is carried out at room temperature (25 ° C). The subject of the invention is also a composition comprising, in a physiologically acceptable medium, a grafted chitosan (I) or (la) as defined above and a cosmetic additive chosen from emulsifiers, preservatives, perfumes, thickeners, oils, waxes, film-forming polymers, dyestuffs.

The composition used according to the invention is generally suitable for topical application to keratin materials, in particular on the skin and hair, and therefore generally comprises a physiologically acceptable medium, ie a medium that is compatible with the skin and / or its integuments. It is preferably a cosmetically acceptable medium, that is to say which has a pleasant color, odor and feel and that does not generate unacceptable discomfort (tingling, tightness, redness), likely to divert the consumer from using this composition.

The grafted chitosan (I) or (la) may be present in the composition used according to the invention in a content ranging from 0.1 to 10% by weight, relative to the total weight of the composition, preferably ranging from 0, 5% to 10% by weight, and preferably ranging from 1 to 8% by weight, and more preferably ranging from 1% to 6% by weight.

The composition according to the invention may be in any of the galenical forms conventionally used for topical application and in particular in the form of dispersions of the lotion or aqueous gel type, emulsions of liquid or semi-liquid consistency of the milk type, obtained by dispersion. a fatty phase in an aqueous phase (O / W) or conversely (W / O), or suspensions or emulsions of soft, semi-solid or solid consistency of the cream or gel type, or multiple emulsions (E / H / E or H / E / H), microemulsions, vesicular dispersions of ionic and / or nonionic type, or wax / aqueous phase dispersions. These compositions are prepared according to the usual methods.

According to a preferred embodiment of the invention, the composition is in the form of an O / W emulsion or an aqueous gel.

Advantageously, the composition used according to the invention comprises water, especially in a content ranging from 10 to 99% by weight, relative to the total weight of the composition, and preferably ranging from 50 to 99% by weight.

According to a first embodiment of the process for treating keratin materials, the process comprises the following steps: topical application to keratin materials of a composition, in particular a cosmetic composition, comprising the grafted chitosan (I), optionally leaving for a time of between 5 seconds and 10 minutes; optionally followed by a step of rinsing the keratin materials, for example with water.

According to a second embodiment of the method for treating keratin materials, the method comprising: topically applying to the keratin materials at least one reducing agent (II), preferably a reducing agent (II), or a composition, in particular a cosmetic composition, the container (composition A), while leaving for a duration ranging from 1 minute to one hour; the application to the treated keratin materials of a composition, in particular a cosmetic composition, comprising at least one grafted chitosan polymer (I) (composition B), the reducing agent (II) being distinct from the grafted chitosan (I)

According to a third embodiment of the process for the treatment of keratin materials, the method comprising: the topical application to keratin materials of a composition, in particular a cosmetic composition, comprising at least one grafted chitosan polymer (I) and at least one reducing agent (II), preferably a reducing agent (II), the reducing agent (II) being distinct from the grafted chitosan (I) leaving for a period ranging from 1 minute to one hour. The subject of the invention is also a kit comprising a first composition (composition B), in particular a cosmetic composition, comprising at least one grafted chitosan (I) as defined above and a second composition (composition A), in particular a cosmetic composition, comprising at least one reducing agent as defined above, the first and second compositions being each packaged in a separate package. The packaging assembly of the compositions is in a known manner any packaging adapted to store the cosmetic compositions (bottles, tube, spray bottle, aerosol bottle in particular).

Such a kit makes it possible to implement the process for treating keratin materials according to the invention. The reducing agent may be selected from thiolated reducing agents and non-thiolated reducing agents.

A thiolated reducing agent refers to a compound comprising one or more thiol groups (SH). This thiol may be a monothiol or a polythiol as described below.

By polythiol compound is meant an entire compound carrying two or more thiol groups SH. It may be a non-polymeric organic molecule carrying two or more thiol groups, or a polymer carrying two or more thiol groups.

The thiol compound used according to the invention must not contain vinyl (C = C) (nonaromatic) or acetylenic (CEC) functions. The polythiol compound may be aromatic, or heteroaromatic, or contain an aromatic radical.

The thiol compound used according to the invention may also contain one or more heteroatoms chosen from O, N, S and / or one or more functions selected from the ester, ketone, amide, urea, isocyanurate and

Preferably, the polythiol compound according to the invention may also contain one or more heteroatoms chosen from O, N, S and / or one or more functions chosen from the ester and ketone functions,

The thiol compound according to the invention denotes a non-polymeric organic compound and can be represented by the formula (IIa) W (SH) n (IIa) in which n denotes an integer greater than or equal to 1, preferably between 1 and 10 preferably between 1 and 4 (limits included). and W denotes a monovalent (n = 1) or multivalent (at least divalent) radical (n> 1) C2-C80 linear or branched or (hetero) cyclic, saturated, an aromatic radical, a heteroaromatic cyclic radical, W moreover contain one or more heteroatoms such as O, N, S, Si and / or one or more functional groups selected from carboxylic acid, esters, ketones, amides, ureas, isocyanurates, preferably esters, ketones, carboxylic acids) and / or substituted by one or more linear or branched C1-C10 alkyl, hydroxyl, amino, (C1-C6) alkyl amino, carboxylic acid, carboxylate, linear or branched C1-C10 alkoxy groups, it being understood that when the radical W is substituted, the Thiol functions may be carried by the substituent (s): and their salts such as those formed from acid or base.

As salts of the compound of formula (IIa) (when it comprises a quaternizable nitrogen atom), mention may be made of: a) the salts obtained by adding the compound (IIa) with a mineral acid, especially chosen from hydrochloric acids, boric, hydrobromic, hydroiodic, sulfuric, nitric, carbonic, phosphoric, triflic, tetrafluoroboric; b) or the salts obtained by adding the compound (IIa) with an organic acid, especially chosen from acetic acid, propionic acid, succinic acid, fumaric acid, lactic acid, glycolic acid, citric acid, gluconic acid, salicylic acid, tartaric acid, terephthalic acid, methylsulfonic acid, ethylsulfonic acid and benzene acid. sulfonic acid, toluene sulfonic acid, methoxysulfinic acid, ethoxysulfinic acid, toluene oxysulphinic acid, phenoxysulfinic acid.

Mention may also be made of the salts obtained by adding the compound of formula (IIa) (when it comprises an acid group) with a mineral base, such as sodium hydroxide, potassium hydroxide, calcium hydroxide or ammonium hydroxide. magnesium hydroxide, lithium hydroxide, and sodium, potassium or calcium carbonates or hydrogencarbonates; or with an organic base such as a primary, secondary or tertiary alkylamine, for example triethylamine or butylamine. This primary, secondary or tertiary alkylamine may comprise one or more nitrogen and / or oxygen atoms and may therefore comprise, for example, one or more alcohol functions; there may be mentioned amino-2-methyl-2-propanol, ethanolamine, triethanolamine, dimethylamino-2-propanol, 2-amino-2- (hydroxymethyl) -1,3-propanediol. Mention may also be made of lysine or 3- (dimethylamino) propylamine.

Advantageously, the salts of the compounds of formula (IIa) (when it comprises an acid group) may be chosen from alkali or alkaline earth salts such as sodium, potassium, calcium, magnesium; ammonium salts.

Advantageously, the salts of the compounds of formula (IIa) (when it comprises a quaternizable nitrogen atom) may be chosen from halides such as chloride, bromide; citrate, acetate, succinate, phosphate, lactate, tatrate.

By cyclic radical is meant a saturated monocyclic radical, hydrocarbon or heterocyclic, a saturated or aromatic polycyclic radical for example biphenyl or condensed rings such as for example the naphthyl radical.

The molar mass of the compounds of formula (IIa) is generally between 70 and 1500 g / mol and preferably between 70 and 500 g / mol.

According to a first embodiment, the thiol compound of formula (IIa) is a monothiol: n = 1 and W is a monovalent radical.

Preferably, according to this first embodiment, W denotes a monovalent radical, linear or branched C2-C20 saturated, or aromatic, W may further contain one or more heteroatoms such as O, N, S, Si, and / or a or more functions selected from carboxylic acid, ester, amide, and / or substituted by one or more linear or branched C1-C4 alkyl, hydroxyl, amino, (C1-C6) alkylamino, carboxylic acid, carboxylate, alkoxy C1-C4 linear or branched, it being understood that when the radical W is substituted, the thiol functions may be borne by the substituent (s).

According to this embodiment, the monothiol compound may be chosen for example from thioglycolic acid, thiolactic acid, thiomalic acid, 2-mercaptopropionic acid, 3-mercaptopropionic acid, thiosalicylic acid, thioglycolic acid, thioproprionic acid, glutathione, cysteine, N-acetyl cysteine, homocysteine, mercaptosuccinic acid, and their C1-C4 alcohol esters; cysteamine, N-acetyl cysteamine; thioglycerol, 2-mercaptoethanol, 1-mercapto-2-propanol, 3-mercapto-1-propanol, 2- (trimethylsilyl) ethanethiol, (3-mercaptopropyl) triethoxysilane. the compounds of formula HS- (CH 2) n -NH- (CH 2) m -NH 2, n and m being integers ranging from 1 to 4, ortho-aminothiophenol, meta-aminothiophenol, para-aminothiophenol.

Preferably, according to this embodiment, the thiol (IIa) is chosen from cysteine, cysteamine, thioglycolic acid and (3-mercaptopropyl) triethoxysilane.

According to a second embodiment, the thiol compound of formula (IIa) is such that n = 2 (dithiol) and W denotes a divalent linear or branched C2-C20 hydrocarbon saturated radical, preferably C2-C12.

According to this embodiment, the polythiol compound of the invention denotes, for example, 1,2-ethanedithiol, 1,2-propanedithiol, 1,3-propanedithiol, 1,4-butanedithiol, 1,6 hexanedithiol, 1,7-heptanedithiol, 1,8-octanedithiol, 1,9-nonanedithiol, 1,10-decanedithiol, 1,12-dodecanedithiol, 2,2-dimethyl-1,3-propanedithiol, 3-methyl-1,5-pentanedithiol, 2-methyl-1,8-octanedithiol,

According to a third embodiment, the thiol unit compound of formula (IIa) is such that n = 3 and W denotes a linear or branched, preferably C2-C12 linear or branched C3-C20 saturated hydrocarbon trivalent radical.

According to this embodiment, the thiol unit compound may be chosen for example from 1,1,1-tris (mercaptomethyl) ethane, 2-ethyl-2-mercaptomethyl-1,3-propanedithiol, 1,2, 3-propanetrithiol.

According to a fourth embodiment, the thiol unit compound of formula (IIa) is such that n = 2 or 3 and W denotes a linear or branched, preferably linear or branched C2-C12 saturated divalent or trivalent hydrocarbon radical C3-C20 , said radical containing one or more non-adjacent heteroatom (s) selected from O, S.

According to this embodiment, the thiol unit compound may be chosen for example from C 2 -C 12 bis-mercaptoalkyl ethers and sulphides, such as bis (2-mercaptoethyl) ether, bis (2-mercaptoethyl) sulphide, bis (2-mercaptoethyl) ether, (2-mercaptoethylthio-3-mercaptopropane) sulfide o (C 1 -C 5) alkanes bis (2-mercapto (C 1 -C 3) alkylthio) or mercaptoalkanes (C 1 -C 5) bis (2-mercapto (C 1 -C 3) alkylthio) ) such as for example bis (2-mercaptoethylthio) methane, 1,2-bis (2-mercaptoethylthio) ethane, 1,3-bis (2-mercaptoethylthio) propane, 1,2-bis (2-mercaptoethylthio) propanethiol, 1,2-bis (2-mercaptoethyl) thio-3-mercaptopropane, 1,2,3-tris (2-mercaptoethylthio) propane

Preferably, according to this embodiment, the compound (IIa) is chosen from 1,2-bis (2-mercaptoethylthio) propanethiol, 1,2,3-tris (2-mercaptoethylthio) propane, tetrakis (2 -mercaptoethylthiomethyl) methane.

According to a fifth embodiment, the thiol unit compound of formula (IIa) is such that n denotes an integer greater than or equal to 2 and W denotes a linear or branched C3-C20 saturated hydrocarbon saturated (at least divalent) radical of preferably C2-C12 linear or branched, said radical containing at least one ester function.

According to this embodiment, the thiol unit compound may be chosen for example from polyol esters (glycols, triols, tetraols, pentaols, hexaols) and from C1-C6 mercaptocarboxylic acid such as ethylene glycol bis (2). -mercaptoacetate), ethylene glycol bis (3-mercaptopropionate), ethylene glycol bis (thioglycolate), trimethylolpropane tris (thioglycolate), trimethylolpropane tris (beta-mercaptopropionate), pentaerythritol tetrakis (thioglycolate), pentaerythritol tetrakis ( .beta.-mercaptopropionate), dipentaerylthritol hexakis (.beta.-mercaptoproprionate), trimethylolpropane tris (2-mercaptoacetate), trimethylolpropane tris (3-mercaptopropionate), pentaerythritol tetrakis (2-mercaptoacetate), pentaerythritol tetrakis (3-mercaptopropionate) -mercaptopropionate), pentaerythritol tetrakis (3-mercaptobutanate), dipentaerythritol hex-3-mercaptopropionate,

Preferably, according to this embodiment, the thiol unit compound is chosen from trimethylolpropane tris (2-mercaptoacetate), trimethylolpropane tris (3-mercaptopropionate), pentaerythritol tetrakis (2-mercaptoacetate), pentaerythritol tetrakis (3- mercaptopropionate), pentaerythritol tetrakis (3-mercaptobutanate), dipentaerythritol hex-3-mercaptopropionate.

In a particularly preferred manner, the thiol-patterned compound is pentaerythritol tetraki s (3- m e r pto p ro p i o n ate).

According to a sixth embodiment, the thiol unit compound of formula (I) is such that n = 4 and W denotes a C4-C20, preferably C8-C14, branched saturated hydrocarbon radical, which is interrupted by one or more sulfur atoms. non-adjacent,

According to this embodiment, the thiol unit compound may be chosen for example from tetrakis (2-mercaptoethylthiomethyl) methane, bis (2-mercaptoethylthio-3-mercaptopropane) sulfide.

According to a seventh embodiment, the thiol unit compound of formula (IIa) is such that n = 2 and W denotes a cyclic divalent hydrocarbon radical optionally containing one or more non-adjacent sulfur atoms, optionally substituted by one or more alkyl radicals. C1-C10 linear or branched.

According to this embodiment, the thiol unit compound may be chosen for example from 1,4-cyclohexane dithiol, 1,4-bis (mercaptomethyl) cyclohexane, 1,1-cyclohexane dithiol, 1,2-cyclohexane dithiol, 1,1-bis (mercaptomethyl) cyclohexane, 2,5-dimercapto-1,4-dithiane.

According to an eighth embodiment, the thiol unit compound of formula (IIa) is such that n = 3 and W denotes a cyclic radical of substituted isocyanurate type.

According to this embodiment, the thiol unit compound may be chosen for example from the polythiols of the isocyanurate class described in US Pat. Nos. 3,676,440 and US20110230585, such as tris ((mercaptopropionyloxy) ethyl) isocyanurate.

According to this embodiment, the thiol-patterned compound refers to the tris ((mercaptopropionyloxy) -ethyl) isocyanurate.

According to a ninth embodiment, the thiol unit compound of formula (IIa) is such that n = 2 or 3 or 4 and W denotes an aromatic radical optionally substituted with one or more identical or different radicals of C1-C10 alkyl type, C1-C10 alkoxy, it being understood that when the radical W is substituted, the thiol functions may be borne by the substituent (s).

According to this embodiment, the thiol unit compound may be chosen, for example, from 1,2-dimercaptobenzene, 1,3-dimercaptobenzene, 1,4-dimercaptobenzene, 1,2-bis (mercaptomethyl) benzene, , 3-bis (mercaptomethyl) benzene, 1,4-bis (mercaptomethyl) benzene, 1,2-bis (2-mercaptoethyl) benzene, 1,3-bis (2-mercaptoethyl) benzene, 1,4 bis (2-mercaptoethyl) benzene, 1,2-bis (2-mercaptoethyleneoxy) benzene, 1,3-bis (2-mercaptoethyleneoxy) benzene, 1,4-bis (2-mercaptoethyleneoxy) benzene, , 2,3-trimercaptobenzene, 1,2,4-trimercaptobenzene, 1,3,5-trimercaptobenzene, 1,2,3-tris (mercaptomethyl) benzene, 1,2,4-tris (mercaptomethyl) benzene 1,3,5-tris (mercaptomethyl) benzene, 1,2,3-tris (2-mercaptoethyl) benzene, 1,2,4-tris (2-mercaptoethyl) benzene, 1,3,5-tris tris (2-mercaptoethyl) benzene, 1,2,3-tris (2-mercaptoethyleneoxy) benzene, 1,2,4-tris (2-mercaptoethyleneoxy) benzene, 1,3,5-tris (2- mercaptoethyleneoxy) benzene, 1,2,3,4-tetramercaptobenzene, 1 2,3,5-tetramercaptobenzene, 1,2,4,5-tetramercaptobenzene, 1,2,3,4-tetrakis (mercaptomethyl) benzene, 1,2,3,5-tetrakis (mercaptomethyl) benzene, 1,2,4,5-tetrakis (mercaptomethyl) benzene, 1,2,3,4-tetrakis (2-mercaptoethyl) benzene, 1,2,3,5-tetrakis (2-mercaptoethyl) benzene, 1,2,4,5-tetrakis (2-mercaptoethyl) benzene, 1,2,3,4-tetrakis (2-mercaptoethyleneoxy) benzene, 1,2,3,5-tetrakis (2-mercaptoethyleneoxy) benzene, 1,2,4,5-tetrakis (2-mercaptoethyleneoxy) benzene, 2,2'-dimercaptobiphenyl, 4,4'-dimercaptobiphenyl, 4,4'-dimercaptobibenzyl, 2,5-toluenedithiol, 3 , 4-toluenedithiol, 1,4-naphthalenedithiol, 1,5-naphthalenedithiol, 2,6-naphthalenedithiol, 2,7-naphthalenedithiol, 2,4-dimethylbenzene-1,3-dithiol, 4,5 1,3-bis (2-mercaptoethylthio) benzene, 1,4-bis (2-mercaptoethylthio) benzene, 1,2-bis (2-dimethylbenzene-1,3-dithiol, 9,10-anthracenedimethanethiol, 1,3-bis (2-mercaptoethylthio) benzene) -mercaptoethylthiomethyl) benzene, 1,3-bis (2-mercaptoethylthiomethyl) benzene, 1,4-bis (2-mercaptoethylthiomethyl) benzene, 1,2,3-tris (2-mercaptoethylthio) benzene, 1,2,4-tris (2-mercaptoethylthio) benzene, 1,3,5-tris (2-mercaptoethylthio) benzene, 1,2,3,4-tetrakis (2-mercaptoethylthio) benzene, 1,2,3,5-tetrakis (2-mercaptoethylthio) benzene, 1,2,4,5- Tetrakis (2-mercaptoethylthio) benzene, 3,4-thiophenedithiol.

According to this embodiment, the compound (IIa) is chosen from 1,2,3-trimercaptobenzene, 1,2,4-trimercaptobenzene, 1,3,5-trimercaptobenzene, 1,2,3-tris ( mercaptomethyl) benzene, 1,2,4-tris (mercaptomethyl) benzene, 1,3,5-tris (mercaptomethyl) benzene, 1,2,3-tris (2-mercaptoethyl) benzene, 1,2, 4-tris (2-mercaptoethyl) benzene, 1,3,5-tris (2-mercaptoethyl) benzene, 1,2,3-tris (2-mercaptoethyleneoxy) benzene, 1,2,4-tris (2-mercaptoethyl) benzene, -mercaptoethyleneoxy) benzene, 1,3,5-tris (2-mercaptoethyleneoxy) benzene, 1,2,3,4-tetramercaptobenzene, 1,2,3,5-tetramercaptobenzene, 1,2,4,5 tetramercaptobenzene, 1,2,3,4-tetrakis (mercaptomethyl) benzene, 1,2,3,5-tetrakis (mercaptomethyl) benzene, 1,2,4,5-tetrakis (mercaptomethyl) benzene, 1,2,3,5-tetrakis (mercaptomethyl) benzene, , 4-Tetrakis (2-mercaptoethyl) benzene, 1,2,3,5-tetrakis (2-mercaptoethyl) benzene, 1,2,4,5-tetrakis (2-mercaptoethyl) benzene, 1,2, 3,4-Tetrakis (2-mercaptoethyleneoxy) benzene, 1,2,3,5-tetrakis (2-mercaptoethyleneoxy) benzene, 1 2,4,5-Tetrakis (2-mercaptoethyleneoxy) benzene, 1,2,3-tris (2-mercaptoethylthio) benzene, 1,2,4-tris (2-mercaptoethylthio) benzene, 1.3.5- tris (2-mercaptoethylthio) benzene, 1,2,3,4-tetrakis (2-mercaptoethylthio) benzene, 1,2,3,5-tetrakis (2-mercaptoethylthio) benzene, 1,2,4,5 Tetrakis (2-mercaptoethylthio) benzene, 3,4-thiophenedithiol.

According to a tenth embodiment, the thiol unit compound of formula (IIa) is such that n = 2 or 3 or 4 and W denotes a fatty acid triglyceride or an optionally substituted vegetable oil, it being understood that when the radical W is substituted, thiol functions may be carried by the substituent (s).

According to this embodiment, the thiol unit compound may be chosen for example from: triglycerides of fatty acids or vegetable oils modified with thiol groups by chemical reaction, for example thiolated soybean oils and soybean oils and thiolated products in particular polymercaptan® products from Chevron Phillips such as polymercaptan 358 (mercaptanized soybean oil) and polymercaptan 407 (mercapto hydroxy soybean oil)

Polymercaptan 358

According to an eleventh embodiment, the thiol unit compound of formula (IIa) is such that n = 2 and W denotes a C2-C0 saturated hydrocarbon divalent radical, substituted with one or more hydroxyl groups.

According to this embodiment, the thiol unit compound may be chosen for example from dithiothreitol, 2,3-dimercapto-1-propanol.

According to a twelfth embodiment, the thiol unit compound of formula (IIa) is such that n = 2 and W denotes a divalent hydrocarbon radical saturated with C2-Cq, substituted by one or more carboxylic acid or carboxylate group (ester group in C2-C5).

According to this embodiment, the thiol unit compound of formula (I) may be meso-2,3-dimercaptosuccinic acid and its C 1 -C 4 alcohol esters.

According to this first variant, the compounds of formula (IIa) for which n denotes an integer ranging from 1 to 4 (inclusive) will be preferred.

Preferably, according to this variant, the compounds of formula (IIa) are chosen from the compounds of the first embodiment, such as, in particular, thioglycolic acid, thiolactic acid, thiomalic acid, 2-mercaptopropionic acid, 3-mercaptopropionic acid, thiosalicylic acid, thiopropionic acid, glutathione, cysteine, N-acetyl cysteine, homocysteine, mercaptosuccinic acid, and their C1-C4 alcohol esters; cysteamine, N-acetyl cysteamine; thioglycerol, 2-mercaptoethanol, 1-mercapto-2-propanol, 3-mercapto-1-propanol and their C1-C4 esters, 2- (trimethylsilyl) ethanethiol, (3-mercaptopropyl) triethoxysilane; the compounds of formula HS- (CH 2) n -NH- (CH 2) m -NH 2, n and m being integers ranging from 1 to 4, ortho-aminothiophenol, meta-aminothiophenol, para-aminothiophenol. ; or among the compounds of the fifth embodiment such as in particular trimethylolpropane tris (2-mercaptoacetate), trimethylolpropane tris (3-mercaptopropionate), pentaerythritol tetrakis (2-mercaptoacetate), pentaerythritol tetrakis (3-mercaptopropionate), pentaerythritol tetrakis (3-mercaptobutanate), dipentaerythritol hex-3-mercaptopropionate, and more particularly pentaerythritol tetrakis (3-mercaptopropionate); or among the compounds of the eleventh embodiment, such as, in particular, dithiothreitol.

Particularly preferably, according to this variant, the compounds of formula (IIa) denote cysteine, thioglycolic acid, (3-mercaptopropyl) triethoxysilane, pentaerythritol tetrakis (3-mercaptopropionate), dithiothreitol.

According to a second variant, the thiolated reductant implemented according to the invention denotes a polymeric compound and can be represented by the formula (Mb) POL (SH) n (Mb) in which n denotes an integer greater than or equal to 5, preferably between 5 and 5000, preferably between 5 and 1000. and POL denotes a multivalent polymeric radical (at least pentavalent) carbon or silicone, POL may also contain one or more heteroatoms such as O, N, S, and / or one or more functions selected from ester, ketone, amide, urea and carbamate functions, and / or be substituted with one or more linear or branched C1-C10 linear or branched C1-C10 alkyl groups, it being understood that when POL is substituted, the thiol functions can be carried by the substituent (s), provided that POL does not designate a chitosan.

The molar mass of the compounds of formula (Mb) is generally between 500 and 400000 g / mol, preferably between 500 and 150 000 g / mol. POL may denote a multivalent radical of the homopolymer or copolymer type; POL can denote a polymeric radical of star, comb, brush or dendritic type

The POL radical may be of natural origin (such as polysaccharides, peptides) or synthetic (such as acrylic polymers, polyesters, polyglycols).

The thiol functions (-SH) may be terminal and / or pendant groups.

According to a first embodiment, the thiolated compound of formula (Mb) is such that POL denotes a polymeric hydrocarbon radical.

Examples include the polymers described in the following articles: Polymers containing groups of biological activity, CG Overberger et al., Polytechnic Institute of Brooklyn, http://pac.iupac.org/publications/pac/pdf/1962/pdf/ 0402x0521 .pdf and Mercaptan-containing Polymers, Advances in Polymer Science Volume 15, 1974, pp 61-90.

In particular, mention may be made of thiol-containing compounds of formula (Mb) such as poly (vinylmercaptan), poly (4-mercaptostyrene), poly (vinylbenzylmercaptan), poly (4-mercaptostyrene) -co-poly (methylmethacrylate) and also polymers containing the amide functions in the polymer such as poly (hexamethylene adipamide thiolated).

The compounds of formula (Mb) also denote proteins and peptides with thiol units, for example the structures represented in the following table:

The thiolated compounds of formula (II) also denote compounds of formula (Mb) such that POL denotes a so-called dendrimer radical, branched or hyperbranched polymer and the thiol groups are terminal. Examples that may be mentioned are the polymers described in the article Proqress in Orqanic Coatings, Volume 63, Issue 1, July 2008, Pages 100-109.

As an example of synthesis of such polymers, mention may be made of the synthesis described in this article, in which the Boltorn H40 polymer is converted into the thiolated polymer of formula (II) according to the scheme below:

The structure of the thiolated polymer (Mb) obtained is given below:

The thiol unit compound of formula (Mb) may also denote a hyperbranched or dendritic polymer modified with thiol functions as described in application FR 2761691.

Polymers of polypropylene ether glycol bis (beta-mercaptopropionate) type are also usable. They are prepared from polypropylene ether glycol (e.g., Pluracol P201, Wyandotte Chemical Corp.) and beta-mercaptopropionic acid by esterification reaction and known to those skilled in the art.

Certain thiol-patterned polymers of formula (Mb) are also commercially available such as THIOCURE® products from Bruno Brock, THIOCURE® ETTMP 1300 (Ethoxylated-Trimethylolpropan Tri-3-Mercaptopropionate (CAS # 345352-19-4) and THIOCURE® ETTMP 700 (Ethoxylated-Trimethylolpropan Tri-3-

Mercaptopropionate (CAS # 345352-19-4);

According to a second embodiment, the compound of formula (Mb) is such that POL denotes a silicone polymer radical.

Among the polythiol inorganic polymers mention may be made of polythiol silicones

The polythiol silicones are in particular polydimethylsiloxane comprising two or more thiol groups such as, for example, the products SMS-022, SMS 042 and SMS 992 sold by Gelest Inc.

Preferably, the thiolated reductant is chosen from the thiol compounds of formula (IIa) with n = 1 and W denotes a saturated linear or branched C2-C20 monovalent radical, an aromatic radical, W which may also contain one or more heteroatoms such as O, N, S, Si, and / or one or more functional groups selected from carboxylic acid, ester, amide, and / or substituted by one or more linear or branched C1-C4 alkyl, hydroxyl, amino, ( C1-C6 alkyl) amino, carboxylic acid, carboxylate, linear or branched C1-C4 alkoxy, it being understood that when the radical W is substituted, the thiol functions may be borne by the substituent (s).

In particular, the monothiol compound is chosen from thioglycolic acid, thiolactic acid, thiomalic acid, 2-mercaptopropionic acid, 3-mercaptopropionic acid, thiosalicylic acid, thiopropionic acid and glutathione. cysteine, N-acetyl cysteine, homocysteine, mercaptosuccinic acid, and their C1-C4 alcohol esters; cysteamine, N-acetylcysteamine,, thioglycerol, 2-mercaptoethanol, 1-mercapto-2-propanol, 3-mercapto-1-propanol and their C 1 -C 4 esters, 2- (trimethylsilyl) ethanethiol, (3-mercaptopropyl) triethoxysilane. the compounds of formula HS- (CH 2) n -NH- (CH 2) m -NH 2, n and m being integers ranging from 1 to 4, ortho-aminothiophenol, meta-aminothiophenol, para-aminothiophenol.

In a particularly preferred manner, the thiol (II) is chosen from cysteine, cysteamine, thioglycolic acid and its salts, (3-mercaptopropyl) triethoxysilane.

Preferably, the thiol is chosen from: cysteine, cysteamine, thioglycolic acid and its salts, (3-mercaptopropyl) triethoxysilane, dithiothreitol, pentaerhytritol tetra (3-methylcarboxylic acid).

"Non-thiolated reducing agent" herein means a reducing agent without any thiol group. The non-thiolated reducing agent may preferably be selected from the group consisting of sulfites, bisulfites, sulfinates, phosphines, sugars, reductones and hydrides. More preferably, the unthiolated reducing agent may be selected from ammonium sulfites and bisulfites as well as metal sulfites and bisulfites, more preferably alkali metal or alkaline earth metal sulfites and bisulfites, and more preferably sulphites and sodium bisulfites.

As sulfinates, there may be mentioned sulfinic acid salts and benzenesulfinic acid salts such as sodium salts thereof. The sulfinic acid derivatives described in FR-A-2814948 can also be used. A preferred sulfinate compound is 2-hydroxy-2-sulfinatoacetic acid, the disodium salt. As phosphines, we can mention monophosphine and diphosphines, as described in document FR-A-2870119. According to one particular embodiment of the present invention, the phosphine (s) may be chosen from the compounds of formula (I) below:

wherein: - L is a linker (linking agent) which represents a covalent bond or a divalent hydrocarbon radical optionally comprising one or more heteroatoms selected from an oxygen atom, a sulfur atom, an atom nitrogen and a silicon atom; m is an integer equal to 0 or 1; q is an integer equal to 1 or 2; p is an integer equal to 0 or 1; R31, R32 and R33, which may be identical or different, represent: a hydrogen atom; a halogen atom; a hydroxyl radical; a carboxyl radical; a monovalent hydrocarbon-based radical optionally comprising one or more heteroatoms selected from a sulfur atom, an oxygen atom, a nitrogen atom, a phosphorus atom and a silicon atom, optionally substituted with one or more radicals chosen from: a halogen atom, a hydroxyl radical, an alkoxy radical, a haloalkyl radical, an amino radical, a carboxyl radical, an alkoxycarbonyl radical, an amido radical, an alkylaminocarbonyl radical or a radical; acylamino, a mono- or di (alkyl) amino radical, a mono- or di (hydroxyalkyl) amino radical, an N-aryl-N-alkylamino radical, an aromatic or heteroaromatic ring, which is unsubstituted or substituted with a radical or a plurality of radicals chosen from a halogen atom, a hydroxyl radical, an alkoxy radical and a mono- or di (alkyl) amino radical, a cyano radical, a radical which increases the solubility of phosphine in water, such as sulphonate radicals sulphonates, phosphonates or carboxylates, a substituted or unsubstituted aromatic or nonaromatic heterocyclic radical; a substituted or unsubstituted aryl radical; a substituted or unsubstituted arylalkyl radical; an arylalkyloxy radical; a substituted or unsubstituted aromatic or nonaromatic heterocyclic radical; a silyl radical; it being understood that: - when q = 1, m = 0 and p = 1; when q = 2, m = 1 and p = 0 or 1, with: when p = 0, the linker L is attached to the phosphorus atom; and when p = 1, linker L is attached to one of R31, R32 or R33, and acid addition salts thereof.

In all the above definitions, when a radical is substituted, the substituents are selected from halo, hydroxyl, alkyl, haloalkyl, alkoxy, amino, mono- or dialkylamino, mono- or dihydroxyalkylamino, and a carboxyl. For example, the p-methoxyphenyl radical is a substituted aryl radical.

Preferably, the radicals R31, R32 and R33 do not simultaneously represent a hydrogen atom.

Advantageously, but optionally, at least one of the radicals R 31, R 32 and R 33 denotes, as hydrocarbon-based radical, an optionally substituted alkyl radical.

According to a particular embodiment of the invention, R31, R32 and R33 are chosen from a hydrogen atom; an alkyl radical; a cycloalkyl radical optionally substituted with one or more alkyl radicals; an alkoxy radical; an alkoxyalkyl radical; a haloalkyl radical; a cyanoalkyl radical; a hydroxyalkyl radical; a carboxyalkyl radical; a halogen atom; a hydroxyl radical; a carboxyl radical; an alkenyl radical; a mono- or dialkylamino radical; an N-aryl-N-alkylaminoalkyl radical; an aryl radical optionally substituted with one or more radicals chosen from an alkyl radical, an alkoxy radical, a mono- or dialkylamino radical, a mono- or dialkylaminoalkyl radical, a haloalkyl radical, a hydroxyl radical, a carboxyl radical, a halogen atom, and an aryl radical substituted with a mono- or dialkylaminoalkyl radical; an arylalkyl radical; an arylalkyloxy radical; a pyrrolidino radical; a furyl radical; a morpholino radical; a thienyl radical; a pyridyl radical; a trialkylsilyl radical; and an alkyl radical substituted with a pyrrolidino radical, a furyl radical, a morpholino radical or a thienyl radical. For example, R31, R32 and R33 may be selected from a hydrogen atom; a methyl radical; an ethyl radical; a propyl radical; an isopropyl radical; an n-butyl radical; an isobutyl radical; a tert-butyl radical; an octyl radical; a cyclohexyl radical; a cyclopentyl radical; a methoxy radical; an ethoxy radical; a methoxypropyl radical; a chloroethyl radical; a cyanoethyl radical; a hydroxymethyl radical; a hydroxypropyl radical; a carboxyethyl radical; a chlorine atom; a hydroxyl radical; a carboxyl radical; a trifluoromethyl radical; a chloromethyl radical; an allyl radical; a vinyl radical; a dimethylamino radical; a diethylamino radical; a di (isopropyl) amino radical; a phenyl radical; an o-tolyl radical; an m-tolyl radical; a p-tolyl radical; a dimethylphenyl radical; a trimethylphenyl radical; an o-methoxyphenyl radical; an m-methoxyphenyl radical; a p-methoxyphenyl radical; a dimethoxyphenyl radical; a trimethoxyphenyl radical; an o- (dimethylamino) phenyl radical; an m- (dimethylamino) phenyl radical; a p- (dimethylamino) phenyl radical; a di (tert-butyl) phenyl radical; a tri (tert-butyl) phenyl radical; a trifluoromethylphenyl radical; a bis (trifluoromethyl) phenyl radical; an o-fluorophenyl radical; an m-fluorophenyl radical; a p-fluorophenyl radical; an o-chlorophenyl radical; an m-chlorophenyl radical; a p-chlorophenyl radical; an o-hydroxyphenyl radical; an m-hydroxyphenyl radical; a p-hydroxyphenyl radical; a 4- (diethylaminomethyl) phenyl radical; a 3,5-dimethyl-4-methoxyphenyl radical; a 2-methylbiphenyl radical; a benzyl radical; a benzyloxy radical; a naphthyl radical; a morpholino radical; a morpholinomethyl radical; a pyrrolidino radical; a furyl radical; a pyridyl radical; a thienyl radical; a trimethylsilyl radical; a 2- (4-diethylaminomethylphenyl) phenyl radical; a 5-methyl-2-isopropylcyclohexyl radical; an N-methyl-N-phenylaminomethyl radical; and a carboxyphenyl radical.

Phosphines which can be used in the context of the invention can optionally be salified with strong mineral acids, for example HCl, HBr, H 2 SO 4 or HBF 4, or organic acids, for example acetic acid, lactic acid, tartaric acid, citric acid or succinic acid.

According to a particular embodiment of the invention, the phosphine (s) which is (are) usable in the context of the invention is (are) chosen from monophosphines. For example, when the phosphine (s) is (are) of the formula (I), q is then preferably equal to 1.

Examples of monophosphines that may be mentioned include tri (hydroxymethyl) phosphine; tri (hydroxypropyl) phosphine; bis (hydroxymethyl) (phenyl) phosphine; allyldiphenylphosphine; benzyldiphenylphosphine; bis (3,4,5-trimethoxyphenyl) chlorophosphine; bis (3,4,5-trimethoxyphenyl) phosphine; benzyloxy (diisopropylamino) methylphosphine; bis (diisopropylamino) chlorophosphine; bis (2-cyanoethyl) phosphine; bis (3,5-di-tert-butylphenyl) chlorophosphine; bis (3,5-di-tert-butyl-phenyl) phosphine; bis (diethylamino) methylphosphine; bis (diethylamino) chlorophosphine; bis (diethylamino) phenylphosphine; bis (3,5-dimethyl-4-methoxyphenyl) chlorophosphine; bis (3,5-dimethyl-4-methoxyphenyl) phosphine; bis (3,5-dimethylphenyl) chlorophosphine; bis (3,5-dimethylphenyl) diethylaminophosphine; bis (3,5-dimethylphenyl) phosphine; bis (3,5-ditrifluoromethylphenyl) chlorophosphine; bis (3,5-ditrifluoromethylphenyl) phosphine; bis (4-fluorophenyl) chlorophosphine; bis (2-furyl) chlorophosphine; bis (2-furyl) phosphine; bis (hydroxymethyl) phenylphosphine; bis (4-methoxyphenyl) phenylphosphine; bis (3,5-dimethylphenyl) phosphine; bis (3,5-di-tert-butylphenyl) chlorophosphine; bis (3,5-di-tert-butylphenyl) phosphine; bis (3,5-ditrifluoromethylphenyl) chlorophosphine; bis (3,5-ditrifluoromethylphenyl) phosphine; bis (4-fluorophenyl) chlorophosphine; bis (4-methoxyphenyl) chlorophosphine; bis (4-methoxyphenyl) phenylphosphine; bis (4-methylphenyl) chlorophosphine; bis (4-methylphenyl) phosphine; bis (4-trifluoromethylphenyl) chlorophosphine; bis (4-trifluoromethylphenyl) phosphine; bis (diethylamino) methylphosphine; bis (diethylamino) phenylphosphine; bis (hydroxymethyl) phenylphosphine; bis (o-tolyl) chlorophosphine; bis (o-tolyl) phosphine; bis (pyrrolidino) methylphosphine; butyldichlorophosphine; butyldiphenylphosphine; tert-butyldiphenylphosphine; cyclohexyl (diethylamino) chlorophosphine; cyclohexyl (dimethylamino) chlorophosphine; cyclohexyldichlorophosphine; cyclohexyldiphenylphosphine; 2-chloroethyldiphenylphosphine; 2- (dicyclohexylphosphino) biphenyl; 2-dicyclohexylphosphino-2 '- (N, N-dimethylamino) biphenyl; diethyl-aminodiethylphosphine; diméthylaminodichlorophosphine; (4-dimethylaminophenyl) diphenylphosphine; N - [(diphenyl-phosphinyl) methyl] -N-methylaniline; o-diphenylphosphinobenzoic acid; 2-methoxy (dichlorophosphino) benzene; 4-methoxyphenyl (diethylamino) chlorophosphine; 4-methoxyphenyl (dimethylamino) chlorophosphine; (2-methoxyphenyl) methylphenylphosphine; 2-methoxyphosphinobenzene; (5-methyl-2-isopropylcyclohexyl) diphenylphosphine; triphenylphosphine; diallylphenylphosphine; dibenzylphosphine; dibutylphenylphosphine; dibutylphosphine; dicyclohexylchlorophosphine; dicyclohexylphenylphosphine; dicyclohexylphosphine; diethylchlorophosphine; diethylphenylphosphine; diethylphosphine; diisobutylphosphine; diisopropylchlorophosphine; diisopropylphosphine; dimethyl (phenyl) phosphine; dimethyl (trimethylsilyl) phosphine; dimethylchlorophosphine; diphenyl (o-tolyl) phosphine; diphenyl (p-tolyl) phosphine; diphenyl (trimethylsilyl) phosphine; diphenylchlorophosphine; diphenylphosphine; diphenylpropylphosphine; diphenylvinylphosphine; di-tert-butylchlorophosphine; di-tert-butylhydroxyphosphine; di-tert-butylmethylphosphine; di-tert-butylphenylphosphine; di-tert-butylphosphine; divinylphenylphosphine; ethyl-dichlorophosphine; the ethyldiphenylphosphine; isopropyl-dichlorophosphine; methoxydiethoxyphosphine; methyl-dichlorophosphine; methyldiphenylphosphine; methyl-phenylchlorophosphine; phenylphosphine; propyldichlorophosphine; tert-butylbis (trimethylsilyl) phosphine; tert-butyldichlorophosphine; tert-butyldiethylphosphine; tert-butyldiphenylphosphine; tert-butylphosphine; tri (m-tolyl) phosphine; tri (o-tolyl) phosphine; tri (p-tolyl) phosphine; tricyclohexylphosphine; tricyclopentylphosphine; triethylphosphine; triisobutylphosphine; triisopropylphosphine; trimethylphosphine; tri-n-butylphosphine; tri-n-octylphosphine; tripropylphosphine; tris (1-naphthyl) phosphine; tris (2,4,6-trimethylphenyl) phosphine; tris (2,6-dimethoxyphenyl) phosphine; tris (2-carboxyethyl) phosphine; tris (2-cyanoethyl) phosphine; tris (2-furyl) phosphine; tris (2-methoxyphenyl) phosphine; tris (2-thienyl) phosphine; tris (3,5-dimethyl-4-methoxy) phosphine; tris (3-chlorophenyl) phosphine; tris (3-fluoro-phenyl) phosphine; tris (3-methoxyphenyl) phosphine; tris (3-methoxypropyl) phosphine; tris (4-chlorophenyl) phosphine; tris (4-fluorophenyl) phosphine; tris (4-methoxyphenyl) phosphine; tris (4-morpholino) phosphine; tris (hydroxymethyl) phosphine; tris (trimethylsilyl) phosphine; tris [3,5-bis (trifluoromethyl) phenyl] phosphine; tri-tert-butylphosphine; 2-cyanoethyldiphenylphosphine; 2-dicyclohexylphosphino-2'-methylbiphenyl; bis (2,4,6-trimethylphenyl) phosphine; and 2- (di-tert-butyl-phosphino) biphenyl.

Preferably, the monophosphines are chosen from trihydroxymethylphosphine; trihydroxypropylphosphine; and bis (hydroxymethyl) phenylphosphine.

According to another particular embodiment of the invention, the phosphine (s) which is (are) usable in the context of the invention are (are) diphosphines. When the phosphine (s) is (are) of the formula (I), q is then preferably equal to 2.

Preferably, p is 0 and the linker L is a covalent bond or a divalent radical which is selected from a binaphthylene radical; a methylene radical; an ethylene radical; a propylene radical; a butylene radical; a pentylene radical; a hexylene radical; a phenylene radical; a meta-dimethylenebenzene radical; an N-methyl-N'-methylhydrazo radical; a vinylene radical; and a diethyleneoxy radical.

As examples of diphosphines which are useful in the context of the invention, there may be mentioned 2,2'-bis (dicyclohexylphosphino) -1,1'-binaphthyl; 2,2'-bis [bis (3,5-dimethylphenylphosphino)] - 1,1 '-binaphthyl; 1,4-bis [bis (3,5-dimethylphenyl) phosphino] butane; 1,2-bis [bis (3,5-dimethylphenyl) phosphino] ethane; bis [bis (3,5-dimethylphenyl) phosphino] methane; 1,5-bis [bis (3,5-dimethylphenyl) phosphino] pentane; 1,3-bis [bis (3,5-dimethylphenyl) phosphino] propane; 2,2'-bis [bis (3,5-ditrifluoromethylphenyl) phosphino] -1,1'-binaphthyl; 1,4-bis [bis (3,5-ditrifluoromethylphenyl) phosphino] butane; 1,2-bis [bis (3,5-ditrifluoromethylphenyl) phosphino] ethane; bis [bis (3,5-trifluoromethylphenyl) phosphino] methane; 1,5-bis- [bis (3,5-ditrifluoromethylphenyl) phosphino] pentane; 1,3-bis [bis (3,5-ditrifluoromethylphenyl) phosphino] propane; 1,2-bis (di-tert-butylphosphino) benzene; 1,4-bis (di-tert-butylphosphino) butane; 1,2-bis (di-tert-butylphosphino) ethane; 1,3-bis (di-tert-butylphosphinomethyl) benzene; 1,3-bis (di-tert-butylphosphino) propane; 1,2-bis (dichlorophosphino) benzene; 1,3-bis (dichlorophosphino) benzene; 1,4-bis (dichlorophosphino) benzene; 1,4-bis (dichlorophosphino) butane; 1,2-bis (dichlorophosphino) -1,2-dimethylhydrazine; 1,2-bis (dichlorophosphino) ethane; bis (dichlorophosphino) methane; 1,3-bis (dichlorophosphino) propane; 1,2-bis (dicyclohexyl-phosphino) benzene; 2,2'-bis (dicyclohexylphosphino) -1,1'-binaphthyl; 1,4-bis (dicyclohexylphosphino) butane; (2R, 3R) bis (dicyclohexylphosphino) butane; (2S, 3S) -bis (dicyclohexylphosphino) butane; 1,2-bis (dicyclohexylphosphino) ethane; bis (dicyclohexylphosphino) methane; 1,3-bis (dicyclohexylphosphino) propane; bis [2- (4-diethylaminomethylphenyl) phenylphosphino] ethyl ether; 1,2-bis (diethylphosphino) ethane; 1,2-bis (dimethyl-phosphino) benzene; 1,4-bis (dimethylphosphino) butane; 1,2-bis (dimethylphosphino) ethane; bis (dimethylphosphino) methane; 1,3-bis (dimethylphosphino) propane; 1,2-bis (diphenylphosphino) benzene; 1,3-bis (diphenylphosphino) benzene; 1,4-bis (diphenylphosphino) benzene; 2,2'-bis (diphenylphosphino) -1,1'-binaphthyl; 1,4-bis (di-phenylphosphino) butane; 1,2-bis (diphenylphosphino) ethane; cis-1,2-bis (diphenylphosphino) ethylene; trans-1,2-bis (diphenylphosphino) ethylene; bis (2-diphenylphosphino) ethyl ether; 1,6-bis (diphenylphosphino) hexane; bis (diphenylphosphino) methane; 1,5-bis (diphenylphosphino) pentane; 1,3-bis (diphenylphosphino) propane; 1,2-bis (ditrifluoromethylphosphino) ethane; 1,2-bis [(2-methoxyphenyl) phenylphosphino] ethane; 1,2-bis (phenylphosphino) ethane; 1,3-bis (phenylphosphino) propane; bis-2 - [(phenyl) (3-pyridyl) phosphinoethyl] ether; 1,2-bis (phosphino) benzene; 1,2-bis (phosphino) ethane; bis (phosphino) methane; 1,2-bis (trifluoromethyl) phosphino) ethane; bis (di-tert-butylphosphino) pentane; and tetraphenylbiphosphine.

According to a particular embodiment of the invention, the phosphine (s) which is (are) usable in the context of the invention is (are) soluble in a cosmetically acceptable medium. . Preferably, the phosphine (s) which is (are) usable in the context of the invention is (are) soluble in water.

In the context of the present invention, the term "water-soluble" means any phosphine whose solubility in water is greater than 0.01% by weight at 20 ° C. Preferably, the phosphine is trihydroxymethylphosphine.

As sugars, we can mention ribose, glucose, maltose, galactose, lactose, and xylose.

As reductones, we can mention ascorbic acid and erythorbic acid. As hydrides, we may mention boron hydrides such as sodium borohydride, lithium hydride and phosphorous hydride. Hydride precursors, and in particular boron hydrides such as diborane, tetraborane, pentaborane, decaborane and dodecaborane, may be used.

Preferred non-thiol reducing agents are selected from sulfites, bisulfites and phosphines. The reducing agent may be present in the composition (in particular the composition A) used according to the invention in a content ranging from 0.1 to 50% by weight, relative to the total weight of the composition, in particular from 0.1 to 10% by weight, and preferably ranging from 1 to 10% by weight.

The reducing agent or the composition containing it applied to the keratin materials is advantageously left for a period ranging from 1 minutes to one hour, preferably ranging from 3 to 30 minutes, and preferably ranging from 5 to 15 minutes.

After the step of applying the reducing agent to the keratin materials, a rinsing step may be carried out with water, optionally mixed with a surfactant. Surfactants known and adapted for cleaning keratin materials can be used. The rinsing step is advantageously carried out when the reducing agent (II), in particular a thiol of formula (II) (in particular for a monothiol (IIa) with n = 1), is applied to the keratin materials.

Then, it is possible to carry out a step of removing excess water from the surface of treated keratin materials, for example using a towel or an absorbent paper.

Next, the step of applying a composition, in particular a cosmetic composition, comprising the grafted chitosan (I) is then carried out.

According to a first variant of the method according to the invention, the method comprises the following steps (in the indicated order):

Topical application to keratinous materials of a composition comprising a reducing agent (II), and preferably a thiolated reducing agent of formula (II), leaving for a period ranging from 1 minute to 1 hour; optionally, a rinsing step is carried out with water or a mixture of water and surfactant, if necessary a step is performed to remove the excess water at the surface of the keratin materials;

Then application on treated keratin materials of a composition comprising the grafted chitosan (I).

Advantageously, the process is carried out with the rinsing step.

According to a second variant embodiment of the method according to the invention, the method comprises the following steps (in the indicated order):

Topical application to keratinous materials of a composition comprising a reducing agent (II), preferably a thiolated reducing agent of formula (II) and a grafted chitosan (I), allowing to be left for a duration ranging from 1 minute to 1 hour ; Optionally, a rinsing step is carried out with water or a mixture of water and surfactant

Optionally, a step is performed to remove the excess water at the surface of the keratin materials.

Advantageously, the process is carried out with a rinsing step.

The method according to the invention may comprise a step of applying a composition comprising a chemical oxidizing agent (composition C), this step being carried out after the step of applying the grafted chitosan (I).

The term "chemical oxidizing agent" means an oxidizing agent different from the oxygen in the air. Preferably, the composition of the invention contains one or more chemical oxidizing agents.

The chemical oxidizing agents are, for example, hydrogen peroxide, urea peroxide, alkali metal bromates, persalts such as perborates and persulfates. Hydrogen peroxide is particularly preferred.

More particularly, the chemical oxidizing agent (s) is (are) chosen from hydrogen peroxide, urea peroxide, alkali metal peroxides, such as sodium peroxide, alkali metal bromates, peroxygenated salts such as, for example, persulfates, perborates, peracids and their precursors and alkali or alkaline earth metal percarbonates. Iodate salts The chemical oxidizing agent is advantageously hydrogen peroxide. The chemical oxidizing agent may be present in a content ranging from 0.1 to 50% by weight, and even more preferably from 0.5 to 20% by weight, better still from 1 to 15% by weight relative to the weight of the composition. The subject of the invention is also a cosmetic process for treating human body odors, in particular axillary odors and possibly human perspiration, comprising the topical application to the skin of a composition, in particular a cosmetic composition, comprising, in a physiologically acceptable medium, a chitosan polymer whose amino groups are grafted with thiol-functional groups of formula (I) as defined above.

The method implemented according to the invention makes it possible to mask, absorb, improve and / or reduce the unpleasant odor resulting from the decomposition of human sweat.

Advantageously, for the process according to the invention, 0.01 to 0.5 g of cosmetic composition comprising the grafted chitosan polymer, in particular 0.05 to 0.1 g of composition, can be applied to the skin. cm2 of skin. The application of the cosmetic composition used according to the invention is carried out according to the usual techniques, for example by application (in particular of creams, gels, serums, lotions) to the skin to be treated, in particular the skin of the skin. underarms or feet. The subject of the invention is also a cosmetic process for combating the formation of scalp dandruff, in particular those caused by yeasts of the genus Malassezia, characterized in that it comprises the application, on the scalp, of a composition, in particular a cosmetic composition, comprising a chitosan polymer whose amino groups are grafted with thiol-functional groups of formula (I) as defined previously. The subject of the invention is also the use of a chitosan polymer whose amino groups are grafted with thiol-functional groups of formula (I) as defined previously as anti-dandruff agent. The subject of the invention is also a method for the cosmetic treatment of hair comprising the topical application to the hair of a composition, in particular a cosmetic composition, comprising a chitosan polymer whose amino groups are grafted with thiol-functional groups of formula (I ) as defined above. The treatment method may be a method of imparting to the hair the softness and / or ease of combing the hair. The invention will now be described with reference to the following examples given for illustrative and non-limiting. In the compositions, the contents are expressed in percent by weight.

Synthesis Example 1 (Polymer 1): Chitosan Functionalized at 8% Thiol Group

with a = 0.52; b = 0.30; c = 0.08 n being such as non-grafted chitosan with a molecular weight Mn = 28 000 Daltons

In a flask, 25 g of chitosan (Zenvivo® Protect from Clariant with a degree of acetylation (% mol) = 30% and a molecular weight Mn = 28 kDa) were solubilized in 400 ml of water containing 25 g of Lactic acid. Then a solution of 12.5 g of homocysteine tiolactone hydrochloride in 100 ml of water and then 20 g of pyridine was added.

After 48 hours stirring at room temperature (25 ° C), 20 g of sodium bicarbonate was added slowly. The reaction medium was stirred at ambient temperature (25 ° C.) for 18 hours. The reaction mixture was then introduced into a dialysis tube (Spectra / Por Dialysis Membrane MWCO 3500, NFW 54mm, Diam 34mm, Vol / length 9.3ml / cm, Spectrumlabs.com ref 132725) and dialyzed in 2 liters of water. for 3 days, replacing the water 2 times a day. The aqueous solution was lyophilized to give a yellow fibrous solid product.

23 g of a solid product (powder) of beige color were thus obtained.

Elemental analyzes and 1H NMR in deuterated water confirm a grafting rate of 8%.

Example 1

Demonstration of the film-forming property of the polymer 1A) 300 μl of a 1% by weight aqueous solution of polymer 1 at pH 4 (spontaneous) were applied to a glass plate and to a Bioskin® artificial skin support. Plate 20 - reference K278 from the company Maprecos.

Then allowed to air dry for 15 minutes.

After drying, it was found that a homogeneous film was formed on the surface of the glass plate and the equivalent skin support.

Thus, the polymer 1 is a film-forming polymer. B) 10 ml of 0.9M aqueous NaCl solution were applied to the film deposited on the artificial skin support using a pipette at a distance of 5 cm from the surface of the film. It was allowed to air dry for 15 minutes. After drying, it was found that the appearance of the film is not modified in contact with the saline solution: the film therefore has good persistence with water. C) The film deposited on the artificial skin support obtained in A) was applied to 100 μl of an aqueous solution of hydrogen peroxide at 4% by weight. It was allowed to dry for 15 minutes at room temperature. Then 10 ml of 0.9 M aqueous NaCl solution was applied to the film with a pipette at a distance of 5 cm from the surface of the film. It was allowed to air dry for 15 minutes. After drying, it was found that the appearance of the film is not modified in contact with the saline solution: the film therefore has good persistence with water.

Examples 2 to 4 comparatives:

Demonstration of the deodorant effect of the polymer used according to the invention

The following compositions were prepared:

Composition 1: water

Composition 2: 5% by weight aqueous solution of MA of chitosan Zenvivo Protect from Clariant

Composition 3: aqueous solution at 5% by weight MA of polymer 1 Preparation of the substrate.

The pieces of human stratum corneum are glued on Scotch (reference 1526886 of the company Office Depot) ensuring that the outer surface of the stratum corneum is not in contact directly on the tape. The substrates are then cut into a size band about 2 cm long and 1 cm wide and used with the scotch in the lower part and the outer surface of the horny stratum in the upper part.

The outer surface of the stratum corneum was cleaned with a wipe impregnated with ethanol.

Application of the compositions:

Examples 1 to 3:

100 μl of each of compositions 1 to 3 were respectively applied to the surface of the stratum corneum and allowed to stand for 10 minutes and then rinsed with 13 ml of 0.9 M NaCl aqueous solution and then the surface was wiped with a absorbent paper.

The treated stratum corneum strips were cut into small pieces about 3 mm x 3 mm in size and placed in a plastic bottle. 100 μl of human sweat was added, closed and shaken the vial. The vial was then placed in an incubator for 24 hours (37 ° C, 5% CO2).

The sweat odor felt by opening each vial (examples 1 to 3) was then evaluated with a panel of 5 people.

The following results were obtained:

The results obtained show that the stratum corneum treated with the polymer 1 (Example 4) has the lowest odor of sweat perceived by the panel. Thus, the treatment of the stratum corneum with the polymer according to the invention gives a good deodorant property.

Example 5

A deodorant is prepared having the following composition: - polymer of Example 1 1g - hydroxyethyl cellulose (NATROSOL® 250 HHR CS from Ashland) 0.2 g - Preservatives qs - Water qs 100 g

The composition obtained is applied to the underarm skin. there is a decrease in odors due to perspiration.

Example 6

Demonstration of the anti-dandruff effect on reconstructed human skin The anti-dandruff activity of Polymer 1 was evaluated and compared on reconstructed human skin colonized with the strains Malasezzia restricta and Malassezia globosa.

Strains Malassezia restricta CBS 7877 and Malassezia globosa CBS 7874 were purchased from the CBS collection center and received on an agar slope. On receipt, they were subcultured on modified LeMing agar and Notman agar (LNm - reference for composition - "ATCC Medium: 2737 Leeming & Notman agar Modified MLNA media": https://www.atcc.org/~/media /8E142808FA514998A7AA819B24E60A7D.ashx) and incubated at 30 ° C.

The following compositions were prepared:

In a glass pill, 60 mg of polymer and 2 ml of 1% acetic acid in water were added. The mixture was stirred in a water bath at 60 ° C for one hour and then cooled to room temperature. The formulations were used within 2 hours after preparation.

The following compositions were thus produced:

Composition A:

Acetic acid at 1% by weight in water Composition B: 3% by weight aqueous solution of MA of chitosan Zenvivo Protect from Clariant and 1% by weight of acetic acid

Composition C: aqueous solution containing 3% by weight of Polymer 1 and 1% by weight of acetic acid

40 μl of each composition were applied and spread on EPISKIN® reconstructed human skin from Episkin (corresponding to an applied amount of 50 mg / cm 2)

After 24 hours, the Malassezia restricta and Malassezia globosa strains were applied to the reconstructed skins and cultured at 32 ° C in ambient air for 24 hours. The microorganisms were recovered and cultured on LNm agar for enumeration. The number of colonies was counted (average of 3 trials).

The lower the number of colonies, the more effective the treatment.

The following results were obtained:

IND: number of colonies too large to count

The results obtained show a significant reduction in the number of colonies with polymer 1 (composition C) compared with unmodified chitosan (composition B) and the vehicle (composition A) for both colonies of M restricta and M globosa.

Polymer 1 has good anti-dandruff efficacy on M. restricta and M. globosa. Example 7 Dandruff Lotion

An antidandruff lotion is prepared comprising the following ingredients:

- Polymer of Example 1 5 g MA - Preservatives qs - Water qs 100 g

The lotion applied to the hair and scalp helps to reduce the appearance of dandruff.

Examples 8 to 10 Comparative

The following compositions were prepared:

Composition 1A: water

Composition 1B (except the invention): aqueous solution containing 2% by weight of chitosan Zenvivo Protect from Clariant

Composition 1C (invention): aqueous solution containing 2% by weight of polymer 1

The compositions were prepared one hour before use; they have a spontaneous pH of 5. The compositions were stirred just before their use.

5.4 g of each composition were applied to a lock of discolored hair (2.7 g of hair per wick) leaving for 30 minutes. A post-treatment was then carried out by applying 5 g of aqueous solution of hydrogen peroxide (10 volume) and leaving for 5 minutes.

The treated locks were then rinsed with water and then washed with 2 g of shampoo (aqueous solution at 1% by weight of sodium lauryl sulphate) for 45 seconds and then rinsed with water and left to air-dried. for one night. This complete treatment was done twice.

The properties of softness and combing of the wicks treated by a panel of 4 people were then evaluated.

Wick A: treated with the composition 1A Wick B: treated with the composition 1B Wick C: treated with the composition 1C

The softness was evaluated by the panel of 4 people by touching the same treated and assigning the following score: 0: very rough touch (wick A treated with the composition 1 A) 5: very soft touch (untreated wick)

The combing facility was evaluated by combing the wick held with the fingers and assigning the following score: 0: wick difficult to comb (wick A treated with composition 1A) 5: wick easy to comb (untreated wick)

The following results were obtained:

Sweetness:

Combing:

The results obtained show that the polymer 1 gives the hair a good softness and ease of combing (Example 10), with results superior to those obtained with unmodified chitosan (Example 9).

Examples 11 to 13 Comparative

The same compositions 1A, 1B, 1C described in the preceding example were used.

The compositions were prepared one hour before use and were stirred just prior to use.

Composition 2 was also prepared: aqueous solution of ammonium thioglycolate (1M); spontaneous pH about 8

2.7 g of the composition 2 were applied to 3 strands of discolored hair (2.7 g of hair per wick) leaving for 5 minutes. The treated locks were then rinsed with water and then wrung out. 5.4 g of Composition 1C was applied to a strand of discolored hair (2.7 g of hair per wick) leaving for 5 minutes. The treated locks were then rinsed with water and then wrung out. A post-treatment was then carried out by applying 5 g of aqueous solution of hydrogen peroxide (10 volume) and leaving for 5 minutes.

The treated locks were then rinsed with water and then washed with 2 g of shampoo (aqueous solution at 1% by weight of sodium lauryl sulphate) for 45 seconds and then rinsed with water and left to air dry. for one night. This complete washing treatment was performed twice.

The process was repeated replacing the composition 1C on the one hand with the composition 1A and on the other hand with the composition 1B for comparison.

The properties of softness and combing of the wicks treated by a panel of 4 people were then evaluated.

Wick A ': treated with the composition 1A Wick B': treated with the composition 1B Wick C ': treated with the composition 1C

The following results were obtained:

Sweetness:

Combing:

The results obtained show that the polymer 1 gives the hair a good softness and ease of combing (Example 13), with results superior to those obtained with unmodified chitosan (Example 12).

Claims (29)

1. Cosmetic process for the treatment of keratin materials, comprising the topical application to the keratin materials of a composition, in particular a cosmetic composition, comprising, in a physiologically acceptable medium, a chitosan polymer whose amino groups are grafted with thiol-functional groups of formula (I): (I) wherein R 'independently represents H or an acetyl group or a -CO-L-SH group, the polymer containing at least one R' = -CO-L-SH group, L being a divalent hydrocarbon group comprising from 1 20 to 20 carbon atoms, preferably 2 to 10 carbon atoms, linear, branched or cyclic, saturated or unsaturated, and may be interrupted by one or more non-adjacent heteroatoms selected from oxygen, sulfur or -NH groups; , -CO-, -CONH-, -COO-, -O-CO-N (Ra) -, in particular -O-CO-NH-, -N (Rb) -CO-N (Rc) -, in particular -NH-CO-NH-, said divalent group possibly being substituted for one or more groups selected from hydroxyl groups, amine -N (Ra) (Rb) (Rc), thiol, carboxylic acid, esters -CÜ2Ra, amide - N (Ra) CO- (Rb), cyano, acyl (C 1 -C 4) amino, ureido -N (Ra) -CO-N (Ra) (Rb) with Ra, Rb, Rc independently denoting an atom of hydrogen or a linear or branched C-1 -C alkyl radical, preferably linear; n varies from 5 to 2000. 2. Method according to the preceding claim, characterized in that the grafted chitosan (I) has a molar degree of grafting in -CO-L-SH groups ranging from 0.1 to 50%, preferably ranging from 1 to 30%, and preferably ranging from 1 to 20%. 3. Method according to one of the preceding claims, characterized in that L is a divalent hydrocarbon radical C- | -C20> preferably C- | -C- o, linear, branched or cyclic, saturated or unsaturated ( of which aromatic), which can be interrupted by one or more non-adjacent heteroatoms chosen from oxygen or by one or more non-adjacent groups chosen from -NH-, -CO-, -O-CO-, -NH-CO-. 4. Method according to one of the preceding claims, characterized in that the grafted chitosan (I) has a degree of acetylation (-CO-CH3) ranging from 0 to 50%, preferably ranging from 5 to 30%, and more preferably ranging from 10 to 30%. 5. Method according to one of the preceding claims, characterized in that n ranges from 5 to 280, preferably from 15 to 165. 6. Method according to one of the preceding claims, characterized in that the grafted chitosan polymer is of formula (la): wherein the grafted chitosan comprises units bearing a free amino group, units carrying an N-acetylated amino group, and units bearing an amino group grafted with a -CO-L-SH group; b is from 0 to 0.5, preferably from 0.05 to 0.30, and more preferably from 0.1 to 0.30; c is from 0.001 to 0.5, preferably from 0.01 to 0.3, and more preferably from 0.01 to 0.2; anda + b + c = 1 L and n having the meanings according to claim 1. 7. Method according to one of the preceding claims, characterized in that L is chosen from the following groups: * representing the bond with the thiol group; ** representing the bond with the C (O) NH group of chitosan; 8. Method according to one of the preceding claims, characterized in that L is the divalent group * representing the bond with the thiol group; ** representing the bond with the C (0) NH group of chitosan 9. Method according to one of the preceding claims, characterized in that the grafted chitosan (I) or (la) is present in the composition in a content ranging from 0.1 to 10% by weight, relative to the total weight of the composition, preferably ranging from 0.5% to 10% by weight, and preferably ranging from 1 to 8% by weight, and more preferably ranging from 1% to 6% by weight. 10. Method according to one of the preceding claims, characterized in that it comprises the following steps: the topical application to the keratin materials of a composition, in particular a cosmetic composition, comprising the grafted chitosan (I) or (la), possibly leaving for a period of between 5 seconds and 10 minutes; optionally followed by a step of rinsing the keratin materials, for example with water. 11. Method according to one of claims 1 to 9, characterized in that it comprises the following steps: the topical application to the keratin materials of at least one reducing agent (II), preferably a reducing agent (II ), or of a composition, in particular a cosmetic composition, the container (composition A), leaving for a period ranging from 1 minute to one hour; the application to the treated keratin materials of a composition, in particular a cosmetic composition, comprising at least one grafted chitosan polymer (I) or (la) (composition B), the reducing agent (II) being distinct from the grafted chitosan (I) or (the). 12. Method according to one of claims 1 to 9, characterized in that it comprises the topical application on keratin materials of a composition, including cosmetic, comprising at least one grafted chitosan polymer (I) or (la) and at least one reducing agent (II), preferably a reducing agent (II), wherein the reducing agent (II) is distinct from the grafted chitosan (I) or (la), allowing a duration of from 1 minute to one o'clock. 13. Method according to one of claims 11 or 12, characterized in that the reducing agent is chosen from: (i) non-polymeric organic thiol reducers of formula (IIa) W (SH) n (MA) in which n denotes an integer greater than or equal to 1, preferably between 1 and 10, preferably between 1 and 4 and W denotes a monovalent (n = 1) or multivalent (at least divalent) radical (n> 1) linear C2-C80 or branched or (hetero) cyclic, saturated, an aromatic radical, a heteroaromatic cyclic radical, W may also contain one or more heteroatoms such as O, N, S, Si and / or one or more functions chosen from carboxylic acid functions , esters, ketones, amides, ureas, isocyanurates, preferably esters, ketones, carboxylic acids) and / or be substituted by one or more linear or branched C1-C10 alkyl groups, hydroxyl, amino, (C1-C6) alkyl amino, acidic carboxylic acid, carboxylate, alkoxy C1-C10 linear Ires or branched, it being understood that when the radical W is substituted, the thiol functions can be borne by the substituent (s); and their salts. (ii) polymeric thiol reducers of formula (Mb): POL (SH) n (Mb) in which n denotes an integer greater than or equal to 5, preferably between 5 and 5000, preferably between 5 and 1000, and POL denotes a multivalent polymeric radical (at least pentavalent) carbon or silicone, POL may further contain one or more heteroatoms such as O, N, S, and / or one or more functions selected from the functions esters, ketones, amides, ureas, carbamates, and / or be substituted by one or more linear or branched linear or branched C1-C10 alkyl C1-C10 alkyl groups, it being understood that when POL is substituted, the thiol functions may be borne by the substituent (s) . (iii) non-thiol reducers selected from the group consisting of sulfites, bisulfites, sulfinates, phosphines, sugars, reductones and hydrides. 14. Process according to the preceding claim, characterized in that the thiolated compound (Mb) has a molar mass of between 70 and 1500 g / mol and preferably between 70 and 500 g / mol. 15. Process according to claim 13, characterized in that the thiolated reductant is chosen from: thioglycolic acid, thiolactic acid, thiomalic acid, 2-mercaptopropionic acid, 3-mercaptopropionic acid, thiosalicylic acid, thioproprionic acid, glutathione, cysteine, N-acetyl cysteine, homocysteine, mercaptosuccinic acid, and their C1-C4 alcohol esters; cysteamine, N-acetyl cysteamine; thioglycerol, 2-mercaptoethanol, 1-mercapto-2-propanol, 3-mercapto-1-propanol, 2- (trimethylsilyl) ethanethiol, (3-mercaptopropyl) triethoxysilane. the compounds of formula HS- (CH 2) n -NH- (CH 2) m -NH 2, n and m being integers from 1 to 4, ortho-aminothiophenol, meta-aminothiophenol, para-aminothiophenol; 1,2-ethanedithiol, 1,2-propanedithiol, 1,3-propanedithiol, 1,4-butanedithiol, 1,6-hexanedithiol, 1,7-heptanedithiol, 1,8-octanedithiol, 1,9-nonanedithiol, 1,10-decanedithiol, 1,12-dodecanedithiol, 2,2-dimethyl-1,3-propanedithiol, 3-methyl-1,5-pentanedithiol, 2-methyl-1 8-octanedithiol; 1,1,1-tris (mercaptomethyl) ethane, 2-ethyl-2-mercaptomethyl-1,3-propanedithiol, 1,2,3-propanetrithiol; bis (2-mercaptoethyl) ether, bis (2-mercaptoethyl) sulfide, bis- (2-mercaptoethylthio-3-mercaptopropane) sulfide; bis (2-mercaptoethylthio) methane, 1,2-bis (2-mercaptoethylthio) ethane, 1,3-bis (2-mercaptoethylthio) propane, 1,2-bis (2-mercaptoethylthio) propanethiol, 1 2-bis (2-mercaptoethyl) thio-3-mercaptopropane, 1,2,3-tris (2-mercaptoethylthio) propane; ethylene glycol bis (2-mercaptoacetate), ethylene glycol bis (3-mercaptopropionate), ethylene glycol bis (thioglycolate), trimethylolpropane tris (thioglycolate), trimethylolpropane tris (beta-mercaptopropionate), pentaerythritol tetrakis ( thioglycolate), pentaerythritol tetrakis (.beta.-mercaptopropionate), dipentaerylthritol hexakis (.beta.-mercaptoproprionate), trimethylolpropane tris (2-mercaptoacetate), trimethylolpropane tris (3-mercaptopropionate), pentaerythritol tetrakis (2-mercaptoacetate) ), pentaerythritol tetrakis (3-mercaptopropionate), pentaerythritol tetrakis (3-mercaptobutanate), dipentaerythritol hex-3-mercaptopropionate; tetrakis (2-mercaptoethylthiomethyl) methane, bis- (2-mercaptoethylthio-3-mercaptopropane) sulfide; 1,4-cyclohexane dithiol, 1,4-bis (mercaptomethyl) cyclohexane, 1,1-cyclohexane dithiol, 1,2-cyclohexane dithiol, 1,1-bis (mercaptomethyl) cyclohexane, 2,5 -dimercapto-1,4-dithiane; tris ((mercaptopropionyloxy) -ethyl) isocyanurate; 1,2-dimercaptobenzene, 1,3-dimercaptobenzene, 1,4-dimercaptobenzene, 1,2-bis (mercaptomethyl) benzene, 1,3-bis (mercaptomethyl) benzene, 1,4-bis (mercaptomethyl) ) benzene, 1,2-bis (2-mercaptoethyl) benzene, 1,3-bis (2-mercaptoethyl) benzene, 1,4-bis (2-mercaptoethyl) benzene, 1,2-bis (2) -mercaptoethyleneoxy) benzene, 1,3-bis (2-mercaptoethyleneoxy) benzene, 1,4-bis (2-mercaptoethyleneoxy) benzene, 1,2,3-trimercaptobenzene, 1,2,4-trimercaptobenzene, 1,3,5-trimercaptobenzene, 1,2,3-tris (mercaptomethyl) benzene, 1,2,4-tris (mercaptomethyl) benzene, 1,3,5-tris (mercaptomethyl) benzene, 1, 2,3-tris (2-mercaptoethyl) benzene, 1,2,4-tris (2-mercaptoethyl) benzene, 1,3,5-tris (2-mercaptoethyl) benzene, 1,2,3-tris (2-mercaptoethyleneoxy) benzene, 1,2,4-tris (2-mercaptoethyleneoxy) benzene, 1,3,5-tris (2-mercaptoethyleneoxy) benzene, 1,2,3,4-tetramercaptobenzene, , 2,3,5-tetramercaptobenzene, 1,2,4,5-tetramercaptobenzene, 1,2,3,4-tetrakis (mercaptometh yl) benzene, 1,2,3,5-tetrakis (mercaptomethyl) benzene, 1,2,4,5-tetrakis (mercaptomethyl) benzene, 1,2,3,4-tetrakis (2-mercaptoethyl) benzene , 1,2,3,5-tetrakis (2-mercaptoethyl) benzene, 1,2,4,5-tetrakis (2-mercaptoethyl) benzene, 1,2,3,4-tetrakis (2-mercaptoethyleneoxy) benzene, 1,2,3,5-tetrakis (2-mercaptoethyleneoxy) benzene, 1,2,4,5-tetrakis (2-mercaptoethyleneoxy) benzene, 2,2'-dimercaptobiphenyl, 4,4'- dimercaptobiphenyl, 4,4'-dimercaptobibenzyl, 2,5-toluenedithiol, 3,4-toluenedithiol, 1,4-naphthalenedithiol, 1,5-naphthalenedithiol, 2,6-naphthalenedithiol, 2,7- naphthalenedithiol, 2,4-dimethylbenzene-1,3-dithiol, 4,5-dimethylbenzene-1,3-dithiol, 9,10-anthracenedimethanethiol, 1,3-bis (2-mercaptoethylthio) benzene, 4-bis (2-mercaptoethylthio) benzene, 1,2-bis (2-mercaptoethylthiomethyl) benzene, 1,3-bis (2-mercaptoethylthiomethyl) benzene, 1,4-bis (2-mercaptoethylthiomethyl) benzene, 1,2,3-tris (2-mercaptoethylthio) benzene, 1,2, 4-tris (2-mercaptoethylthio) benzene, 1,3,5-tris (2-mercaptoethylthio) benzene, 1,2,3,4-tetrakis (2-mercaptoethylthio) benzene, 1,2,3,5 -tetrakis (2-mercaptoethylthio) benzene, 1,2,4,5-tetrakis (2-mercaptoethylthio) benzene, 3,4-thiophenedithiol. dithiothreitol, 2,3-dimercapto-1-propanol; meso-2,3-dimercaptosuccinic acid and its C1-C4 alcohol esters. 16. Process according to any one of claims 13, characterized in that the thiol compound is chosen from cysteine, cysteamine, thioglycolic acid and its salts, (3-mercaptopropyl) triethoxysilane, dithiothreitol and pentaerhytritol tetra. (3-mercaptopropionate). 17. A method according to any one of claims 11 to 16, characterized in that the reducing agent applied to the keratin materials is left for a period ranging from 3 to 30 minutes to one hour, preferably from 5 to 45 minutes. 18. A method according to any one of claims 11 to 16, characterized in that after the step of applying the reducer to the keratin materials is carried out a rinsing step with water, optionally mixed with a surfactant. . 19. Method according to the preceding claim, characterized in that after the rinsing step, a step is performed to remove excess water from the surface of the treated keratin materials. 20. Process according to any one of the preceding claims, characterized in that it comprises a step of applying a composition comprising a chemical oxidizing agent, this step being carried out after the step of applying the grafted chitosan (I ). 21. Method according to the preceding claim, characterized in that the chemical oxidizing agent is chosen from hydrogen peroxide, urea peroxide, alkali metal bromates, persalts such as perborates and persulfates, and preferably hydrogen peroxide. 22. Process according to any one of the preceding claims, characterized in that it is carried out on the skin to treat human body odors, in particular axillary odors and possibly human perspiration. 23. A method according to any one of claims 1 to 21, characterized in that it is performed on the scalp to fight against the formation of dandruff scalp, including those caused by yeasts of the genus Malassezia. 24. Method according to any one of claims 1 to 21, characterized in that it is performed on the hair to give the hair the softness and / or ease of combing hair. 25. A composition comprising, in a physiologically acceptable medium, a polymer (I) or (la) as defined in one of claims 1 to 8 and a cosmetic additive chosen from emulsifiers, preservatives, perfumes, thickeners, oils, waxes, film-forming polymers, dyestuffs. 26. Composition according to the preceding claim, characterized in that the polymer (I) or (la) is present in a content ranging from 0.1 to 10% by weight, relative to the total weight of the composition, preferably from 0.5% to 10% by weight, and preferably ranging from 1 to 8% by weight, and more preferably ranging from 1% to 6% by weight. 27. Composition according to one of claims 25 or 26, characterized in that it comprises a reducing agent as defined in one of claims 13 to 16. 28. Composition according to the preceding claim, characterized in that the reducing agent is present in a content ranging from 0.1 to 10% by weight, relative to the total weight of the composition, and preferably ranging from 1 to 10%. in weight. 29. Kit comprising a first composition, in particular a cosmetic composition, comprising at least one grafted chitosan (I) as defined in one of Claims 1 to 8 and a second composition, in particular a cosmetic composition, comprising at least one reducing agent as defined in one of claims 13 to 16, the first and second compositions being each packaged in a separate package.