EP1448646A2

EP1448646A2 - Adhesive block ethylene copolymers, cosmetic compositions containing same, and use thereof in cosmetics

Info

Publication number: EP1448646A2
Application number: EP02803837A
Authority: EP
Inventors: Nathalie Mougin; Bertrand Lion
Original assignee: LOreal SA
Current assignee: LOreal SA
Priority date: 2001-11-29
Filing date: 2002-11-27
Publication date: 2004-08-25
Also published as: AU2002365296A8; WO2003046032A2; JP2006514701A; WO2003046032A3; AU2002365296A1

Abstract

The invention concerns a linear block ethylene copolymer comprising: at least two blocks with different glass transition temperatures (Tg); at least one of said blocks having a glass transition temperature not higher than 20 °C; said polymer having further an adhesion coefficient or tack higher than 1N. The invention also concerns a cosmetic composition containing said copolymer. The copolymer enhances hair styling power and maintenance of hair lacquer, increases adhesion of nail varnish and improves maintenance and adhesion of a make-up composition.

Description

ETHYLENIC COPOLYMERS ADHESIVE SEQUENCES,

COSMETIC COMPOSITIONS CONTAINING THEM, AND USE THEREOF

OF THESE COPOLYMERS IN COSMETICS

DESCRIPTION

The present invention relates to new polymers of specific structure of the ethylene copolymer type, adhesive blocks. The present invention also relates to a composition, in particular a cosmetic or pharmaceutical composition, in particular a hair composition, comprising said polymer of specific structure.

The invention also relates to the use of these polymers in cosmetics for the treatment of the skin, nails or hair.

The styling compositions (“hair styling”) currently the most widespread on the cosmetic market for shaping (“shaping”) and / or maintaining the hairstyle (“hairstyle”) are nebulisats (“spray”) or gels and styling gels and mousses.

These compositions contain one or more polymer resins, one of the functions of which is to create bonds between the hairs. These compounds are also called "fixatives" and are mixed with various cosmetic additives.

_Moreover,. vinyl polymers with high glass transition temperatures are known in cosmetics from document FR-A- 2,439,798 and are included in particular in styling compositions.

In the field of styling compositions, such polymers, if they provide maintenance of the hairstyle, have the disadvantage of too much friability, which does not allow good ^' hold over time of the hairstyle.

To remedy this reliable nature, the polymers are generally plasticized with plasticizing agents but the latter alter the styling properties of the polymer.

There is therefore a need for a polymer which, when included in a composition, in particular a cosmetic composition, allows this composition not to have the drawbacks, limitations, defects and disadvantages of the compositions of the prior art.

In particular, such a polymer must, in a composition for the treatment of the hair, impart more staying power while retaining a natural effect.

It must in a composition for the treatment of the nails, in two layers, ensure good adhesion of the first layer, and finally, in a composition for the treatment of the skin, it must allow the makeup to adhere to the skin, while by being comfortable, not sticky, and without pulling the skin.

The aim of the present invention is to provide a polymer which meets, inter alia, the needs, criteria and requirements mentioned above and which solves the problems of polymers of the prior art. This object and still others are achieved, in accordance with the present invention, by a linear block ethylenic copolymer comprising: at least two blocks having different glass transition temperatures (Tg);

- at least one of these sequences having a glass transition temperature less than or equal to 20 ° C; said copolymer having, in addition, an adhesion or "tack" value greater than IN.

A subject of the invention is also cosmetic compositions comprising said linear block ethylenic copolymers.

When incorporated into the ^'cosmetic compositions, the copolymers having the specific structure of the invention, allows to obtain extremely interesting properties, it was not possible to obtain with the polymers of the prior art . In general, these polymers have an adhesive character and they thus lead to compositions or systems having improved hold and adhesions.

Thus, when the copolymers according to the invention are used in compositions for the treatment of hair, such as hairsprays or shampoos, they provide more hold, while retaining a natural effect. In compositions for the treatment of nails, such as nail varnishes, they increase the adhesion of the first layer. In compositions for the treatment of the skin, namely in a wide variety of compositions of • makeup, the. copolymers according to the invention improve the adhesion to the skin, provide a comfortable feeling, do not stick to the touch, and do not pull the skin. The invention also relates to a cosmetic process for making up or caring for keratin materials comprising the application to keratin materials of a cosmetic composition according to the invention. The invention therefore also relates to the use of the copolymers according to the invention to improve the styling power and the hold of a hair spray, the use of the copolymers to improve the adhesion of a nail varnish and finally the use of the copolymers to improve the hold and the adhesion of a makeup composition.

The copolymers of the invention therefore provide a solution to the problems posed by the polymers of the prior art. The unexpected advantageous properties of the specific copolymers of the invention, which are basically linear polymers, arise, on the one hand, from this linear character and, on the other hand, from the specific nature of the sequences which constitute them.

In fact, the sequences of the copolymers of the invention are defined by specific glass transition temperatures. Nothing suggested, in the prior art, that by implementing a specifically linear copolymer, and by fixing Tg conditions defined for the sequences constituting the copolymer, it would be possible, according to the invention, to obtain a combination of excellent properties for the copolymer.

Without wishing to be bound by any theory, the advantageous properties of the copolymer according to the invention would come from the fact that the specific structure and the specific choice of the blocks which constitute it, favor the phase separation between the blocks. More precisely, the linear copolymers of the present invention are defined as being ethylenic copolymers. This means that the monomers from which the blocks or blocks constituting this copolymer are derived are monomers with an ethylenic type carbon-carbon unsaturated double bond.

Furthermore, specifically, the copolymer according to the invention is a linear copolymer. This means that the invention does not intend to cover copolymers having a non-linear structure, for example branched, star, grafted, or the like. The linear nature of the copolymers of the invention is important for imparting the advantageous properties described above to the compositions containing it. Advantageously, the copolymer according to the invention is a film-forming polymer, that is to say that it is suitable on its own, or in the presence of an auxiliary film-forming agent, at the temperature ranging from 20 ° C. to 30 ° C. , to form a continuous film (seen with the naked eye) and adhering to a keratinous support. According to the invention, the copolymer comprises at least two blocks or blocks which have different glass transition temperatures (Tg), and, in addition, at least one of these blocks or blocks of the copolymer has a glass transition temperature less than or equal at 20 ° C.

The glass transition temperature Tg being an essential parameter for defining the sequences of the copolymer of the invention and, consequently, the copolymer of the invention, it is important to indicate that the glass transition temperatures of the sequences of the copolymers used in the present invention are measured by differential enthalpy analysis (DSC, “Differential Scanning Calorimetry”, in English) for the dry polymer, at a heating rate of 10 ° C./minute.

The copolymers according to the invention are also defined by a specific mechanical criterion, which is "adhesion" or "tack". According to the invention, the copolymers have an adhesion or tack which is generally greater than IN, preferably greater than 2N, more preferably greater than 3N.

This “adhesion” or “tack”, defined by Fmax, is measured by the following test. Fmax is the maximum tensile force, measured using an extensometer, necessary to take off the respective surfaces, an area of 0.95 cm ² , two rigid glass supports (A) and (B) , inert, non-absorbent, placed opposite each other. Said surfaces have been previously coated with a composition comprising copolymer to be tested, according to the invention, this coating composition has a dry matter concentration of 10% (C) (in grams per 100 grams of composition), and the surfaces of the supports are coated at a rate of 4 / C mg / cm ² .

The surfaces are then dried for 48 hours at 22 ° C, at a relative humidity of 50%, then subjected for 20 seconds to a compression of 3

Newtons and, finally, subjected for 60 seconds to a traction, at a speed of 10 mm / minute.

Each block of the copolymer, according to the invention, comes from one type of monomer or from several different types of monomers.

This means that each block can consist of a homopolymer or a copolymer; this copolymer constituting the sequence can in turn be statistical or alternated.

According to the invention, the copolymer comprises at least two sequences having ^• glass transition temperatures (Tg). Advantageously, the difference in glass transition temperatures between these two sequences, having different glass transition temperatures, is generally 40 to 120 ° C, preferably 40 to 110 ° C and more preferably 40 ° C. at 100 ° C.

The number average mass of the copolymer is generally from 10,000 to 500,000, preferably from 50,000 to 200,000.

Advantageously, the proportion of the Tg sequence less than or equal to 20 ° C. is from 99% to 40% of the polymer, preferably 95 to 55% and more preferably 90 to 50%.

Advantageously, the Tg sequence less than or equal to 20 ° C has a Tg temperature from 20 to -100 ° C, preferably from 20 to -95 ° C, more preferably from 20 to -90 ° C.

The block whose glass transition temperature is less than or equal to 20 ° C., which is a homopolymer or a copolymer, is preferably derived in whole or in part from one or more monomers, which are such that homopolymers prepared from these monomers have glass transition temperatures, less than or equal to 20 ° C.

More preferably, the block, the glass transition temperature of which is less than or equal to 20 ° C., is a homopolymer, constituted by a single type of monomer (whose Tg of the corresponding homopolymer is less than 20 ° C.).

The monomers whose homopolymers have glass transition temperatures less than or equal to 20 ° C. and from which is or are preferably derived the sequence (s) of Tg <20 ° C. of the copolymer of the invention are, preferably chosen from the following monomers: - ethylenic hydrocarbons of 2 to 10 C, such as ethylene, isoprene, and butadiene;

- the acrylates of formula CH ₂ = CHCOORi, Ri representing an alkyl group of 1 to 12 C linear or branched with the exception of the tert-butyl group, in which there are (are) optionally intercalated one or more heteroatoms chosen from 0 , N, S, said an alkyl group which may also be optionally substituted with one or more substituents chosen from hydroxyl groups and halogen atoms (Cl, Br, I and F); - examples of Ri groups are methyl, ethyl, propyl, butyl, isobutyl, hexyl, ethylhexyl, octyl, lauryl, isooctyl, isodecyl, hydroxyethyl, hydroxypropyl, methoxyethyl, ethoxyethyl and methoxypropyl, • another example of Ri for acrylates are the C1 to Cι alkyl groups ₂ - POE (polyoxyethylene), with repetition of the oxyethylene unit from 5 to 30 times, for example POE methoxy, ie the groups Ri = R "- (OC ₂ H) _n -, with R" = Cχ-Cι ₂ alkyl, and n = 5 to 30,

• Ri can also denote a polyoxyethylene group comprising from 5 to 30 ethylene oxide units;

- methacrylates of formula:

R ₂ representing an alkyl group. from 3 to 12 C linear or branched, in which there are (are) optionally intercalated one or more heteroatoms chosen from 0, N and S, said alkyl group being able, in addition, to be optionally substituted by one or more substituents chosen from hydroxyl groups and halogen atoms (Cl, Br, I, F); examples of R groups are hexyl, ethylhexyl, octyl, lauryl, isooctyl, isodecyl, dodecyl, methoxyethyl, methoxypropyl, ethoxyethyl, POE (polyoxyethylene with repetition of the oxyethylene unit 5 to 30 times) and alkyl (Ci to C ₃₀ ) - POE (with repetition of the oxyethylene unit of 5 30 times);

The vinyl esters of formula:

R ₃ -CO-0-CH = CH ₂

where R ₃ represents a linear or branched 2 to 12 C alkyl group; examples of such vinyl esters are: vinyl propionate, vinyl butyrate, vinyl ethylhexanoate, vinyl neononanoate, and vinyl neododecanoate;

- Vinyl ethers and alkyl of 1 to 12 C, such as vinyl ether and methyl, and vinyl ether ethyl;

- N-alkyl (1 to 12 C) acrylamides, such as N-octylacrylamide.

The monomers, which are particularly preferred, are: n-butyl acrylate, ethylhexyl acrylate, isobutyl acrylate, methoxyethyl acrylate, ethoxyethyl (meth) acrylate, (meth) acrylate of n-hexyl.

The glass transition temperature sequence less than or equal to 20 ° C may, in addition to the monomers indicated above, and whose glass transition temperature Tg of the corresponding homopolymer is less than or equal to 20 ° C, include one or more several other different monomers called additional monomers.

This or these additional monomers are, of course, chosen so that the Tg of the sequence is less than ^'or equal to 20 ° C.

Thus, an adequate Tg sequence, less than or equal to 20 ° C, may be formed from a copolymer consisting of a first monomer whose Tg of the corresponding homopolymer is in the range of more than 20 ° C to 200 ° C, and preferably more than 20 ° C to 120 ° C, and a second monomer whose Tg of the corresponding homopolymer is in the range of 20 ° C to -100 ° C.

For example, it is possible to combine in the copolymer forming the block a monomer of Tg (of the corresponding homopolymer) equal to 100 ° C., at a rate of 35% by weight of the total weight of monomers, and a monomer of Tg equal to - 70 ° C, 65% by weight, and the resulting sequence will have a Tg of -30 ° C. These additional monomers which therefore have a

Tg of the equivalent homopolymer, greater than 20 ° C. are chosen in particular from acrylates, methacrylates, meth (acrylamide), vinyl and allylic compounds, etc. The additional monomers (from Tg of

1 corresponding homopolymer> 20 ° C) are preferably chosen from the following monomers:

- vinyl compounds of formula:

CH ₂ = CH-R ₄ , where R ₄ is a hydroxyl group; a group

NH C CH ₃ , an O C CH ₃ group _;

O O

a C ₃ -C ₅ cycloalkyl group; a C ₆ -C ₂ aryl group; a C ₇ -C ₃₀ aralkyl group (C ₁ -C ₄ alkyl group); a 4 to 12-membered heterocyclic group containing one or more heratomas selected from O, N, and S; a heterocyclylalkyl group (C1-C6 alkyl) such as a furfuryl group; said cycloalkyl, aryl, aralkyl, heterocyclic or heterocyclylalkyl groups which may be optionally substituted by one or more substituents chosen from hydroxyl groups, halogen atoms, and alkyl groups of 1 to 4 C ^• linear or branched in which is found (nt) optionally intercalated one or more heteroatoms chosen from 0, N, S and P, and said alkyl groups which may, in addition, be optionally substituted by one or more substituents chosen from hydroxyl groups and halogen atoms (Cl, Br, I and F).

Examples of vinyl monomers are vinylcyclohexane, styrene and vinyl acetate. - The acrylates of formula: CH ₂ = CH-COOR5, where R ₅ is a tert-butyl group, a C ₃ to C ₅ cycloalkyl group; a C20 to C20 aryl group; a C 1 -C ₃₀ aralkyl group (C ₁ -C ₄ alkyl group); a 4 to 12 membered heterocyclic group containing one or more heteroatoms chosen from O, N, and S; a heterocyclylalkyl group (alkyl of C, to C _4), such as a furfuryl group; said cycloalkyl, aryl, aralkyl, heterocyclic or heterocyclylalkyl groups which may be optionally substituted by one or more substituents chosen from hydroxyl groups, halogen atoms, and linear or branched alkyl groups of 1 to 4 C in which is found (nt ) optionally intercalated one or more heteroatoms chosen from 0, N, S and P, said alkyl groups being able, in addition, to be optionally substituted by one or more substituents chosen from hydroxyl groups and halogen atoms (Cl, Br, I and F).

Examples of acrylate monomers are t-butylcyclohexyl, tert-butyl, t-butylbenzyl, furfuryl and isobornyl acrylates; - Methacrylates of formula:

CH ₂ = C (CH ₃ ) -COOR ₆ , where R ₆ is an alkyl group from 1 to 4C, linear or branched, such as a methyl, ethyl, propyl or isobutyl group, said alkyl group possibly being optionally substituted by one or more substituents chosen from hydroxyl groups and halogen atoms (Cl, Br, I and F); a C ₃ -C ₅ cycloalkyl group; a C ₂ o C aryl group; a C ₇ -C ₃₀ aralkyl group (C ₁ -C ₄ alkyl group); a 4 to 12-membered heterocyclic group containing one or more heteroatoms chosen from 0, N, and S; a heterocyclylalkyl group (1-4 C alkyl), such as a furfuryl group; said cycloalkyl, aryl, aralkyl, or heterocyclic groups or heterocyclylalkyl possibly being substituted by one or more substituents chosen from hydroxyl groups, halogen atoms, and alkyl groups of 1 to 4 C linear or branched in which is (are) optionally intercalated (s) one or more heteroatoms chosen • from 0, N, S and P, said alkyl groups possibly also being optionally substituted by one or more substituents chosen from hydroxyl groups and halogen atoms (Cl, Br, I and F).

Examples of methacrylate monomers are methyl, ethyl, n-butyl, isobutyl, t-butylcyclohexyl, t-butylbenzyl, methoxyethyl methoxypropyl and isobornyl methacrylates; - The (meth) acrylamides of formula:

where R and Rs, which are identical or different, each represent a hydrogen atom or an alkyl group of 1 to 12 linear or branched carbon atoms, such as an n-butyl, t-butyl, isopropyl, isohexyl, isooctyl, or isononyl group , and R 'denotes H or methyl.

Examples of (meth) acrylamide monomers are N-butylacrylamide, N-t-butylacrylamide,

N-isopropylacrylamide, N, N-dimethylacrylamide and

N, N-dibutylacrylamide. The preferred monomers from all those mentioned above are chosen from furfuryl acrylates, isobornyl acrylates, tert-butyl tert-butylcyclohexyl, tert-butylbenzyl, methyl, n-butyl, ethyl, isobutyl methacrylates, styrene, vinyl acetate and vinylcyclolexane.

Examples of these additional, particularly preferred, monomers are methyl methacrylate, styrene, (meth) acrylic acid, isobornyl and furfuryl acrylates. This or these additional monomers are generally present in an amount less than or equal to 50% by weight, preferably less than or equal to 45% by weight and, more preferably, less than or equal to 40% by weight of the total weight of the block. of Tg less than or equal to 20 ° C.

Advantageously, the copolymer according to the invention comprises at least one hydrophilic block which comprises hydrophilic monomers.

The hydrophilic sequence can be defined as being a water-soluble or water-dispersible sequence.

The polymer forming the block is water-soluble if it is soluble in water, at a rate of at least 5% by weight, at 25 ° C. The polymer forming the block is water-dispersible, if it forms at a concentration of 5%, at 25 ° C, a stable suspension of fine particles, generally spherical. The average size of the particles constituting said dispersion is less than 1 μm and, more generally, varies between 5 and 400 nm, preferably from 10 to 250 nm. These particle sizes are measured by light scattering.

The hydrophilic block is preferably a block whose glass transition temperature is greater than 20 ° C., but it can also be the block whose glass transition temperature is less than or equal to 20 ° C.

It is known that hydrophilic monomers whose homopolymers have a glass transition temperature below 20 ° C are not common.

Therefore, the hydrophilic block, in the case where it is the Tg block less than or equal to 20 ° C., is advantageously a copolymer. This hydrophilic block therefore therefore comprises one or more hydrophilic monomer (s) whose corresponding homopolymers have glass transition temperatures above 20 ° C. and one or more other non-hydrophilic monomer (s), chosen in particular from those whose homopolymers have Tg less than or equal to 20 ° C.

The proportion of the various hydrophilic and non-hydrophilic monomers being preferably chosen so that the whole of the block constituted by a copolymer has a Tg greater than 20 ° C.

When the hydrophilic block has a glass transition temperature above 20 ° C, it generally comprises from 70 to 100%, and preferably from 80 to 100%, of hydrophilic monomers of which the Tg of the corresponding homopolymers is greater than 20 ° C.

When the hydrophilic block has a glass transition temperature less than or equal to 20 ° C., it generally comprises from 10% to less than 70%, preferably from 20% to 65% of hydrophilic monomers whose Tg of the corresponding homopolymers are higher at 20 ° C.

Examples of hydrophilic monomers whose Tg of the corresponding homopolymer is greater than 20 ° C include cationic monomers, anionic monomers and nonionic monomers:

Examples of cationic monomers are:

- 2-vinylpyridine;

- 4-vinylpiridine;

- dimethylaminoethyl methacrylate

(MADAME) diethylaminoethyl methacrylate (DEAMEA)

- dimethylaminopropylacrylamide; and the salts thereof, whether they are salts of mineral acids, such as sulfuric acid or hydrochloric acid, or salts of organic acid.

These organic acids may have one or more carboxylic, sulfonic, or phosphonic groups. They can be linear, branched or cyclic aliphatic acids or even aromatic acids. These acids may also contain one or more heteroatoms chosen from O and N, for example in the form of hydroxyl groups. One example ^'of alkyl acid is acetic acid CH ₃ COOH.

An example of a polyacid is terephthalic acid. Examples of hydroxy acids are citric acid and tartaric acid.

Examples of anionic monomers are: acrylic acid, methacrylic acid, crotonic acid, maleic anhydride, itaconic acid, fumaric acid, maleic acid; styrenesulfonic acid, acrylamidopropanesulfonic acid, vinylbenzoic acid, vinylphosphoric acid and the salts thereof.

The neutralizer can be an inorganic base, such as LiOH, NaOH, KOH, Ca (OH) ₂ , NH ₄ OH, an organic base, for example a primary, secondary or tertiary ingredient, such as a primary alkylamine such as

1-amino-2-methyl-2-propanol, secondary or tertiary.

Examples of nonionic monomers are: - hydroxyalkyl (meth) acrylates in which the alkyl group has from 2 to 4 C atoms, in particular hydroxyethyl (meth) acrylate, vinyllactam.es, (meth ) acrylamides, (meth) acrylamides of N-Cι-C ₄ alkyl, such as isobutyl acrylamide; and polysaccharide (meth) acrylates such as sucrose acrylate.

It should be noted that even if the copolymer comprises a hydrophilic block, the overall copolymer is not necessarily hydrophilic. The linear, block ethylene copolymers according to the invention are chosen from: - bis-sequenced copolymers;

- triblock copolymers;

- polysequenced copolymers having more than three blocks. In the case of polyblock copolymers

(multiblocks), in which one or two blocks

(sequences) meet the criterion of Tg less than or equal to 20 ° C. The other blocks or sequences then have a Tg greater than 20 ° C and less than 200 ° C. For example, the copolymers can comprise two blocks having a Tg ≤20 ° C and one or two blocks having a Tg> 20 ° C.

The copolymers according to the invention can be prepared by anionic polymerization. Preferably, however, the copolymers according to the invention are in a first mode obtained by controlled radical polymerization, but they can also, according to a second mode, be obtained by conventional radical polymerization.

First mode

The block or block copolymers according to the invention are preferably obtained by controlled radical polymerization, described in particular in "New Method of Polymer Synthesis", Blackie Académie & Professional, London, 1995, volume 2, page 1.

Controlled radical polymerization makes it possible to reduce deactivation reactions of the growing radical species, in particular the termination step, reactions which, in conventional radical polymerization, interrupt the growth of the polymer chain in an irreversible and uncontrolled manner. In order to reduce the probability of termination reactions, it has been proposed to transiently and reversibly block the growing radical species, by forming active species called "dormant" in the form of a low dissociation energy bond.

Thus, the polymerization can be carried out according to the atom transfer technique, or by reaction with a nitroxide, or alternatively according to the "reversible addition-fragmentation chain tr ans fer" technique.

^'A technique of atom-transfer radical-polymerization, also known under the abbreviation ATRP, consists in blocking the radical species growing in the form of C-halide type bond (in the presence of metal / ligand complex). This type of polymerization results in a control of the mass of the polymers formed and in a low polydispersity index.

In general, radical polymerization by atom transfer is carried out by polymerization of one or more polymerizable monomers by the radical route, in the presence of: an initiator having at least one transferable halogen atom,; - a compound comprising a transition metal capable of participating in a step of reduction with the initiator and a polymeric chain - "dormant"; and

- a ligand which can be chosen from compounds comprising a nitrogen (N), oxygen (O), phosphorus (P) or sulfur (S) atom, capable of coordinating by a σ bond to said compound comprising a transition metal, the formation of direct bonds between said compound comprising a transition metal and the polymer being formed being avoided.

The halogen atom is preferably a chlorine or bromine atom.

This process is in particular described in application WO 97/18247 and in the article by Matyjasezwski et al. published in JACS, 117, page 5614 (1995).

The radical polymerization technique by reaction with a nitroxide consists in blocking the growing radical species in the form of a bond of the C-0 NR ₁ R ₂ , R ₁ and R _{2 type which} may be, independently of one another, an alkyl radical having from 2 to 30 carbon atoms or forming both, with the nitrogen atom, a ring having from 4 to 20 carbon atoms, such as for example a 2,2,6 ring , 6-tetramethylpiperidinyl. This polymerization technique is notably described in the articles

"Synthesis of nitroxy-functionalized polybutadiene by anionic polymerization using a nitroxy-functionalized terminator", published in Macromole cul es 1997, volume 30, pages 4238 - 4242, and "Macromolecular engineering via, living free radical polymerizations" published in Macromol. Chem. Phys. 1998, vol. 199, pages 923 - 935, or even in application WO-A-99/03894.

The RAFT polymerization technique (reversiJle addition-fragmentation chain transfer) consists in blocking the growing radical species in the form of a C-S type bond. Dithio compounds such as thiobenzoates, dithiocarbamates or xanthan disulphides are used for this. This technique is notably described in application WO-A-98/58974 and in the article "A more versatile route to block copolymers and other polymers of complex architecture by living radical polymerization: the RAFT process", published in Macromolecules, 1999, volume 32, pages 2071 - 2074.

Second mode

The block or block polymers according to the invention can also be obtained using the conventional radical polymerization technique by carrying out the casting of the monomers in a sequenced manner. In this case, only control of the nature of the sequences is possible (no control of the masses). It involves first polymerizing an Ml monomer in a polymerization reactor; to follow, by kinetics, its consumption over time, then when Ml is consumed at around 95%, then to introduce a new monomer M2 into the polymerization reactor. A block structure polymer of the M1-M2 type is thus easily obtained.

The invention also relates to cosmetic or pharmaceutical compositions comprising the copolymer of specific structure, as described above.

Generally, these compositions contain from 0.1 to 60% by weight, preferably from 0.5 to 50% by weight, and more preferably from 1 to 40% by weight of the copolymer according to the invention.

These cosmetic compositions according to the invention comprise, in addition to said polymers, a physiologically acceptable medium, that is to say a medium compatible with keratin materials, such as the skin, hair, eyelashes, eyebrows and nails. .

In general, it must be considered that the whole of the composition is physiologically acceptable. Said medium, physiologically acceptable, generally comprises an appropriate solvent, physiologically acceptable, in which the copolymer, according to the invention, is in dissolved or dispersed form. The composition can thus comprise, as solvent forming a hydrophilic phase, water or a mixture of water and organic solvent (s) hydrophilic (s) such as alcohols and in particular linear or branched lower monoalcohols having 2 to 5 carbon atoms such as ethanol, isopropanol or n-propanol, and polyols such as glycerin, diglycerin, propylene glycol, sorbitol, pentethylene glycol, and polyethylene glycols. The hydrophilic phase can also contain C ₂ ethers and hydrophilic C ₂ -C aldehydes. The water or the mixture of water and hydrophilic organic solvents may be present in the composition according to the invention in a content ranging from 0% to 99% (in particular 0.1% to 99%) by weight, relative to the total weight of the composition, and preferably from 10% to 80% by weight.

The composition may also comprise a fatty phase, in particular consisting of fatty substances liquid at room temperature (25 ° C. in general) and / or fatty substances solid at ambient temperature such as waxes, pasty fatty substances, gums and their mixtures. . These fatty substances can be of animal, vegetable, mineral or synthetic origin. This fatty phase can, in addition, contain lipophilic organic solvents. As fatty substances liquid at room temperature, often called oils, which can be used in the invention, there may be mentioned: hydrocarbon oils of animal origin such as perhydrosqualene; vegetable hydrocarbon oils such as liquid triglycerides of fatty acids of 4 to 10 carbon atoms such as triglycerides of heptanoic or octanoic acids, or even sunflower, corn, soybean, grape seed, sesame oils, apricot, macadamia, castor, avocado, caprylic / capric acid triglycerides, jojoba oil, shea butter; the linear or branched hydrocarbons, of mineral or synthetic origin such as paraffin oils and their derivatives, petrolatum, polydecenes, hydrogenated polyisobutene such as parlameam; synthetic esters and ethers, in particular of fatty acids such as, for example, Purcellin oil, isopropyl myristate, ethyl-2-hexyl pal itate, octyl-2-dodecyl stearate, 1 ' octyl-2- dodecyl erucate, isostearyl isostearate; hydroxyl esters such as isostearyl lactate, octylhydroxystearate, octyldodecyl hydroxystearate, diisostearylmalate, triisocetyl citrate, heptanoates, octanoates, decanoates of fatty alcohols; polyol esters such as propylene glycol dioctanoate, neopentylglycol diheptanoate, diethylene glycol diisononanoate; and pentaerythritol esters; fatty alcohols having from 12 to 26 carbon atoms such as octyldodecanol, 2-butyloctanol, 2-hexyldecanol, 2-undecylpentadecanol, oleic alcohol; partially hydrocarbon and / or silicone fluorinated oils; silicone oils such as polymethylsiloxanes (PDMS), volatile or not, linear or cyclic, liquid or pasty at room temperature such as cyclomethicones, diethicones, optionally comprising a phenyl group, such as phenyl trimethicones, phenyltrimethylsiloxydiphenyl siloxanes, diphenylmethyldimethyl-trisoxides , diphenyl dimethicones, phenyl dimethicones, polyethylphenyl siloxanes; their mixtures. These oils can be present in a content ranging from 0.01 to 90%, and better still from 0.1 to 85% by weight, relative to the total weight of the composition. The composition according to the invention can also comprise one or more organic solvents, cosmetically acceptable (tolerance, toxicology and touch acceptable).

These solvents can generally be present in a content ranging from 0 to 90%, preferably from 0.1 to 90%, more preferably from 10 to

90% by weight, relative to the total weight of the composition, and better still from 30 to 90%.

As solvents which can be used in the composition of the invention, there may be mentioned the esters of acetic acid such as methyl, ethyl, butyl, amyl, 2-methoxy-ethyl acetate, 'isopropyl; ketones such as methyl ethyl ketone, methyl isobutyl ketone; hydrocarbons such as toluene, xylene, hexane, heptane; aldehydes having 5 to 10 carbon atoms; ethers having at least 3 carbon atoms; and their mixtures.

The waxes can be hydrocarbon, fluorinated and / or silicone and be of vegetable, mineral, animal and / or synthetic origin. In particular, the waxes have a melting point above 25 ° C and better still above 45 ° C.

As wax which can be used in the composition of the invention, mention may be made of beeswax, Carnauba or Candellila wax, paraffin, microcrystalline waxes, ceresin or ozokerite; synthetic waxes such as polyethylene waxes or from Fischer Tropsch, silicone waxes such as alkyl or alkoxy-dimethicone having from 16 to 45 carbon atoms.

The gums are generally high molecular weight polydimethylsiloxanes (PDMS) or cellulose gums or polysaccharides and the pasty bodies are generally hydrocarbon compounds such as lanolines and their derivatives or PDMS. The nature and quantity of the solid bodies depend on the mechanical properties and the desired textures. As an indication, the composition may contain from 0 to 50% by weight of waxes, relative to the total weight of the composition and better still from 1 to 30% by weight.

The polymer can be combined with one or more auxiliary film-forming agents. Such a filification agent can be chosen from all of the compounds known to a person skilled in the art as being capable of fulfilling the desired function, and in particular can be chosen from plasticizing agents and coalescing agents.

The composition according to the invention may also comprise one or more coloring materials chosen from water-soluble dyes, and pulverulent coloring materials such as pigments, nacres and flakes well known to those skilled in the art. The coloring matters can be present, in the composition, in a content ranging from 0.01% to 50% by weight, relative to the weight of the composition, preferably from 0.01% to 30% by weight. The term “pigments” should be understood to mean particles of any shape, white or colored, mineral or organic, insoluble in the physiological medium, intended to color the composition. By nacres, it is necessary to understand particles of any iridescent shape, in particular produced by certain molluscs in their shell or else synthesized.

The pigments can be white or colored, mineral and / or organic. Among the mineral pigments, mention may be made of titanium dioxide, optionally surface-treated, zirconium or cerium oxides, as well as oxides of zinc, iron (black, yellow or red) or chromium, violet of manganese, ultramarine blue, chromium hydrate and ferric blue, metallic powders such as aluminum powder, copper powder.

Among the organic pigments, there may be mentioned carbon black, pigments of the D & C type, and lakes based on cochineal carmine, barium, strontium, calcium, aluminum.

The pearlescent pigments can be chosen from white pearlescent pigments such as mica coated with titanium or bismuth oxychloride, colored pearlescent pigments such as titanium mica coated with iron oxides, mica titanium coated with in particular blue ferric or chromium oxide, titanium mica coated with an organic pigment of the aforementioned type as well as pearlescent pigments based on bismuth oxychloride. The water-soluble dyes are, for example, beet juice, methylene blue.

The composition according to the invention may also further comprise one or more fillers, in particular in a content ranging from 0.01% to 50% by weight, relative to the total weight of the composition, preferably ranging from 0.01% at 30% by weight. By fillers, it is necessary to understand particles of any shape, colorless or white, mineral or synthetic, insoluble in the medium of the composition regardless of the temperature at which the composition is produced. These fillers are used in particular to modify the rheology or the texture of the composition.

The fillers can "be mineral or organic in any form, platelet, spherical or oblong, whatever • the crystallographic form (for example sheet, cubic, hexagonal, orthorombic, etc.). Mention may be made of talc, mica, silica, kaolin, polyamide (Nylon®) (Orgasol® from Atochem), poly-β-alanine and polyethylene powders, powders of tetrafluoroethylene polymers (Teflon®) ), lauroyl-lysine, starch, boron nitride, polymeric hollow microspheres such as those of polyvinylidene chloride / acrylonitrile such as Expancel® (Nobel

Industry), acrylic acid copolymers (Polytrap® from Dow Corning) and silicone resin microbeads (Tospearls® from Toshiba, for example), elastomeric polyorganosiloxane particles, precipitated calcium carbonate, carbonate and

Magnesium hydro-carbonate, hydroxyapatite, hollow silica microspheres (Silica Beads® from Maprecos), glass or ceramic microcapsules, metallic soaps derived from organic carboxylic acids having 8 to 22 carbon atoms, preferably 12 to 18 carbon atoms, for example zinc, magnesium or lithium stearate, zinc laurate, magnesium myristate.

The composition according to the invention may also contain ingredients commonly used in cosmetics, such as vitamins, thickeners, trace elements, softeners, sequestrants, perfumes, alkalizing or acidifying agents, preservatives, sun filters , surfactants, antioxidants, hair loss agents, dandruff agents, propellants, or mixtures thereof.

Of course, a person skilled in the art will take care to choose this or these optional additional compounds, and / or their quantity, in such a way that the advantageous properties of the corresponding composition according to the invention are not, or not substantially, affected by the 'proposed addition. The composition according to the invention can be in particular in the form of a suspension, dispersion, solution, gel, emulsion, in particular oil-in-water (O / W) or water-in-oil (W / O) emulsion ), or multiple (W / O / W or polyol / O / W or O / W / O), in the form of a cream, paste, foam, vesicle dispersion, in particular of ionic lipids or not, of two-phase or multiphase lotion, _spray,. powder, dough, in particular flexible dough (in particular dough having a dynamic viscosity at 25 ° C of the order of 0.1 to 40 Pa.s under a shear speed of 200 s ^-1 , after 10 minutes of measurement in cone / plane geometry). The composition can be anhydrous, for example it can be an anhydrous paste.

Those skilled in the art will be able to choose the appropriate dosage form, as well as its method of preparation, on the basis of his general knowledge, taking into account on the one hand the nature of the constituents used, in particular their solubility in the support, and on the other hand of the application envisaged for the composition. The composition according to the invention can be a makeup composition such as products for the complexion (foundations), blushes or eye shadows, products for the lips, concealer products, blushes, mascaras, eyeliners, eyebrow makeup products, lip pencils or eyes, nail products, such as nail polish, body makeup products, products of ^'make-up hair (mascara or hair spray). The composition according to the invention can also be a hair product, in particular for maintaining the hairstyle or shaping the hair. The hair compositions are preferably shampoos, gels, styling lotions, brushing lotions, fixing and styling compositions such as lacquers or spray.

Lotions can be packaged in various forms, in particular in vaporizers, pump-dispensers or in aerosol containers in order to ensure application of the composition in vaporized form or in the form of foam. Such forms of packaging are indicated, for example when it is desired to obtain a spray, a foam for fixing or treating the hair.

The invention will now be described with reference to the following examples, given by way of illustration and not limitation.

Examples:

Example 1:

Preparation of a difunctional polymerization initiator

A difunctional initiator is prepared according to the following reaction scheme:

THF / triethylamine

HO- (CH ₂ ) ₄ -OH + 2C (CH ₃ ) ₂ (Br) -C (= 0) Br

(CH ₃ ) ₂ BrC-C (= 0) -0- (CH ₂ ) ₄ -0-C (= 0) -C (CH ₃ ) ₂ Br

For this, 18 g (0.2 mole) of

1, 4-butanediol with 100 g of tetrahydrofuran and let the mixture equilibrate for 10 minutes at room temperature. 40.4 g (0.4 moles) of triethylamine are then added slowly over a period of 30 minutes, so that the temperature of the solution does not increase suddenly. 92 g (0.4 mole) of 2-bromoisobutyryl bromide are then added very slowly, over a period of 3 hours, and while cooling to 5 ° C. During this addition, a progressive yellowing of the reaction solution is observed. Stirring is continued overnight at 25 ° C, then the temperature is allowed to gradually rise to room temperature.

The reaction solution is concentrated by evaporation of the THF and the residue is precipitated in water. The aqueous phase is then extracted three times with ethyl ether, then the ethereal phase is dried over magnesium sulfate.

After evaporation of the ether, 63 g of bis (1,4-bromoisobutyrate n-butyl) are thus obtained, which corresponds to a yield of 80%.

Example 2:

Preparation of a poly triblock copolymer (methyl acrylate-butyl b-acrylate-methyl b-acrylate)

Step I: Polymerization of n-butyl acrylate, Tg = -50 ° C 1.43E-03 mol, i.e. 5.54E-01 g of difunctional initiator prepared in Example 1, 2.86E, are mixed in a hermetic reactor comprising a nitrogen inlet and protected from oxygen. -03 mole or 4.10E-01 g of CuBr, 7.81E-01 mole or 100 g of butyl acrylate, and 2.86E-03 mole or 4.95E-01 g of N, N, N ', N '', N '' -pentamethyldiethylenetriamine.

The mixture is heated, under a nitrogen atmosphere, to a temperature of 90 ° C., the nitrogen supply is cut off and this temperature is maintained for 7 h 30 hours, whereby a solution of the polymer is obtained.

This solution of the polymer is passed over a bed of neutral alumina, then the clear solution is precipitated in 5 volumes of a methanol / water mixture (80/20).

Step II: Polymerization of methyl acrylate, Tg = + 10 ° C

1.3 lE-04 mol, or 10.5 g of the preceding macroinitiator, is mixed in a hermetic reactor comprising a nitrogen inlet and protected from oxygen: 2. butyl polyacrylate, 2.62E-04 mol or 2.59E-02 g of CuBr, 8.40 ml of diphenyl diether solvent; 2.62E-04 mole or 4.53E-02 g of N, N, N ', N'',N''-pentamethyldiethylenetriamine, and 3.93E-02 mole or 3.39 g ^' of methyl acrylate monomer.

It is reacted for 4 hours at 90 ° C., then the mixture is allowed to cool to room temperature.

The solution is dissolved in approximately 100 ml of dichloromethane. This solution of the polymer is passed over a bed of neutral alumina, then the clear solution is precipitated in 5 volumes of a methanol / water mixture (80/20). 6 g of polymer in the form of a paste are thus obtained, which corresponds to a yield of 43% by weight.

The paste is washed with heptane while hot to remove any residual monomers therefrom.

The average molar mass by weight and number is determined by liquid chromatography by gel permeation (solvent THF, calibration curve established with linear polystyrene standards). The number-average molar mass (M _n ) is equal to 88,000 g / mole, the weight-average molar mass (M _p ) is equal to 102,000 g / mole.

The copolymer has two glass transition temperatures T _g , the first equal to -47 ° C attributable to the poly (butyl acrylate) block, and the second equal to 10 ° C attributable to the poly (methyl acrylate) blocks.

The “tack” value of this polymer measured by the method described above is 3.5 N.

Example 3:

Preparation of a lacquer

An aerosol is prepared with 100 g of a 9% by weight solution of the copolymer prepared in Example 2 in ethanol and 75 g of dimethylether playing the role of propellant.

The composition is sprayed on locks of brown hair with a length of 18 cm and the hold of the hairstyle and the flexible appearance of the locks are evaluated on a panel of -5 people, using a rating scale ranging from 0 (bad) to 5 (excellent).

The notes obtained are 4 for the holding of the hairstyle and 4 for the flexible aspect of the locks.

Example 4:

Preparation of a "basecoat" for nail polish

The copolymer is dissolved in ethyl acetate: the polymer content of the solution obtained is 25% by weight. The copolymer solution of Example 2 is applied to a nail. After drying for 10 min. , a classic solvent nail polish is applied.

The resistance of the varnish and the impact resistance are improved.

Claims

1. Linear block ethylenic copolymer, comprising: - at least two blocks having different glass transition temperatures (Tg);

- at least one of these sequences having a glass transition temperature less than or equal to 20 ° C; said polymer having, in addition, an adhesion or "tack" value greater than IN.

2. Copolymer according to claim 1, which is a film-forming copolymer.

3. Copolymer according to claim 1, whose adhesion or "tack" value is greater than 2N.

4. Copolymer according to claim 3, whose adhesion or "tack" value is greater than 3N.

5. Copolymer according to any one of claims 1 to 4, in which the difference in the glass transition temperatures (Tg) between the two blocks having different glass transition temperatures is from 40 to 120 ° C.

6. Copolymer according to claim 5, in which the difference in the glass transition temperatures (Tg) between the two blocks having different glass transition temperatures is from 40 to 110 ° C.

7. Copolymer according to claim 6, in which the difference in the glass transition temperatures (Tg) between the two blocks having different glass transition temperatures is from 40 to 100 ° C.

8. Copolymer according to any one of claims 1 to 7, whose number average mass is from 10,000 to 500,000, preferably from 50,000 to 200,000.

9. Copolymer according to any one of claims 1 to 8, in which the proportion of the block having a glass transition temperature less than or equal to 20 ° C is 99 to 40% by mass of the copolymer.

10. The copolymer according to claim 9, in which the proportion of the block having a glass transition temperature less than or equal to 20 ° C is 95 to 55%, preferably 90 to 50% by weight of the copolymer.

11. Copolymer according to any one of claims 1 to 10, whose Tg sequence less than or equal to 20 ° C has a Tg of 20 ° C to -100 ° C.

12. Copolymer according to claim 11, in which the Tg sequence less than or equal to 20 ° C has a Tg of 20 to -95 ° C, preferably of 20 to -90 ° C.

13. Copolymer according to any one of claims 1 to 12, the Tg block of which is less than or equal to 20 ° C, which is a homopolymer or a copolymer, is wholly or partly derived from one or more monomers, which are such as homopolymers prepared from these monomers have glass transition temperatures less than or equal to 20 ° C.

14. The copolymer as claimed in claim 13, in which the block whose glass transition temperature is less than or equal to 20 ° C is a homopolymer consisting of a single type of monomer with Tg <20 ° C.

15. The copolymer according to claim 13 or claim 14, in which the monomers whose homopolymers have glass transition temperatures less than or equal to 20 ° C are chosen from the following monomers:

- ethylenic hydrocarbons from 2 to 10 C, such as ethylene, isoprene, and butadiene; - the acrylates of formula CH ₂ = CHCOORi, Ri representing an alkyl group of 1 to 12 C linear or branched with the exception of the tertiobutyl group, in which there are (are) optionally intercalated one or more heteroatoms chosen from O, N , S, said alkyl group possibly being optionally substituted "with one or more substituents chosen from hydroxyl groups and halogen atoms

(Cl, Br, I and F), where Ri represents a C1 to alkyl

Cι ₂ - POE (polyoxyethylene) with repetition of the oxyethylene unit from 5 to 30 times, for example methoxy-POE, where Ri represents a polyoxyethylene group comprising from 5 to 30 ethylene oxide units;

- methacrylates of formula:

CH ₂ =

R ₂ representing a linear or branched alkyl group from 3 to 12 C, in which there are optionally intercalated one or more heteroatoms chosen from 0, N and S, said group alkyl which may also be optionally substituted with one or more substituents chosen from hydroxyl groups and halogen atoms (Cl, Br, I, F), - vinyl esters of formula:

R ₃ -CO-O-CH = CH ₂

where R ₃ represents a linear or branched 2 to 12 C alkyl group;

- Vinyl and alkyl ethers of 1 to 12 C, such as vinyl ether and methyl, and vinyl and ethyl ether.

- N-alkyl (1 to 12 C) acrylamides, such as N-octylacrylamide.

16. Copolymer according to any one of claims 13 and 15, in which the glass transition temperature sequence less than or equal to 20 ° C, comprises, in addition to the monomer or monomers whose glass transition temperatures of homopolymers prepared from these are less than or equal to 20 ° C, one or more other different monomers or additional monomers.

17. Copolymer according to claim 15, in which the said additional monomer (s) are chosen from the following monomers:

- vinyl compounds of formula:

CH ₂ = CH-R ₄ ,

where R ₄ is a hydroxyl group; a group -NH CH ₃ , an O Ç CH _{3 group}

O O

a C ₃ -C ₆ cycloalkyl group; a _& C ₂₀ aryl group; aralkyl C ₇ -C ₃ o (alkyl Ci -C _4); a 4 to 12-membered heterocyclic group containing one or more heratomas selected from O, N, and S; a heterocyclylalkyl group (C1-C6 alkyl) such as a furfuryl group; said cycloalkyl, aryl, aralkyl, heterocyclic, or heterocyclylalkyl groups which may be optionally substituted by one or more substituents chosen from hydroxyl groups, halogen atoms, and linear or branched alkyl groups of 1 to 4 C in which is found ( nt) optionally intercalated one or more heteroatoms chosen from 0, N, S and P, and said alkyl groups which may, in addition, be optionally substituted by one or more substituents chosen from hydroxyl groups and halogen atoms ( Cl, Br, I and F). - The acrylates of formula:

CH ₂ = CH-COOR ₅ , where R ₅ is a tert-butyl alkyl group; a C ₃ -C ₈ cycloalkyl group; a C ₆ -C ₂₀ aryl group; a C ₇ -C ₃₀ aralkyl group (C ₁ -C ₄ alkyl group); a 4 to 12 membered heterocyclic group containing one or more heteroatoms chosen from O, N, and S; a heterocyclylalkyl group (C1 to C1 alkyl C ₄ ), such as a furfuryl group; said cycloalkyl, aryl, aralkyl, heterocyclic or heterocyclylalkyl groups which may be optionally substituted by one or more substituents chosen from hydroxyl groups, halogen atoms, and linear or branched alkyl groups of 1 to 4 C in which is found (nt ) optionally intercalated one or more heteroatoms chosen from 0, N, S and P, said alkyl groups being able, in addition, to be optionally substituted by one or more substituents chosen from hydroxyl groups and halogen atoms (Cl, Br, I and F);

- The methacrylates of formula: CH ₂ = C (CH ₃ ) -COOR ₆ , where R ₆ is an alkyl group of 1 to 4C, linear or branched, such as a methyl, ethyl, propyl or isobutyl group, said alkyl group may also be optionally substituted by one or more substituents chosen from hydroxyl groups and halogen atoms (Cl, Br, I and F); a C ₃ -C ₅ cycloalkyl group; a C ₂ o aryl group; u C ₃₀ -C ₃₀ aralkyl group (C ₄ -C ₄ alkyl group); a 4 to 12-membered heterocyclic group containing one or more heteroatoms chosen from 0, N, and S; a heterocyclylalkyl group (1-4 C alkyl), such as a furfuryl group; said cycloalkyl, aryl, aralkyl, or heterocyclic or heterocyclylalkyl groups which may be optionally substituted by one or more substituents chosen from hydroxyl groups, halogen atoms, and alkyl groups of 1 to 4 C linear or branched in which there is (are) optionally intercalated (s) one or more heteroatoms chosen from O, N, S and P, said alkyl groups being able, in addition, to be optionally substituted by one or more substituents chosen from hydroxyl groups and atoms halogen (Cl, Br, I and F);

- The (meth) acrylamides of formula:

where R ₇ and R _{8, which are} identical or different, each represent a hydrogen atom or an alkyl group of 1 to 12 linear or branched carbon atoms, such as an n-butyl, t-butyl, isopropyl, isohexyl, isooctyl group, or isononyl, and R 'denotes H or methyl.

18. The copolymer according to claim 16 or claim 17, in which the said additional monomer (s) are present in an amount less than or equal to 50% by weight of the Tg block less than or equal to 20 ° C.

19. The copolymer according to claim 18, in which the said monomer or monomers are present in an amount less than or equal to 45% by weight, preferably less than or equal to 40% by weight of the Tg block of less than or equal to 20 ° C .

20. Copolymer according to any one of claims 16 to 19, in which the Tg block less than or equal to 20 ° C is formed of a copolymer consisting of a first monomer whose Tg of the corresponding homopolymer is in the range of more than 20 ° C to 200 ° C, preferably more than 20 ° C to 120 ° C, and a second monomer whose Tg of the corresponding homopolymer is in the range of 20 ° C to -100 ° C.

21. Copolymer according to any one of claims 1 to 20, comprising at least one hydrophilic block which comprises hydrophilic monomers.

22. The copolymer according to claim 21, in which said hydrophilic block is a glass transition temperature block higher than 20 ° C.

23. The copolymer according to claim 21, in which the hydrophilic block is the glass transition temperature block less than or equal to 20 ° C.

24. Copolymer according to claim 21, the hydrophilic block of which comprises one or more hydrophilic monomer (s) whose corresponding homopolymers have glass transition temperatures above 20 ° C and one or more other non-hydrophilic monomer (s) (s) chosen in particular from those whose homopolymers have Tg less than or equal to 20 ° C.

25. The copolymer according to claim 22 and claim 24, in which the hydrophilic block comprises from 70 to 100%, preferably from 80 to 100% of hydrophilic monomers whose Tg of the corresponding homopolymers are greater than 20 ° C.

26. The copolymer according to claim 22 and claim 23, in which the hydrophilic block comprises from 10 to less than 70%, preferably from 20 to 65%, of hydrophilic monomers whose Tg of the corresponding homopolymers are greater than 20 ° C.

27. Copolymer according to any one of claims 21 to 26, in which the hydrophilic monomers are chosen from cationic monomers, anionic monomers and nonionic monomers.

28. The copolymer according to claim 27, in which the cationic monomers are chosen from 2-vinylpyridine; 4-vinylpyridine, dimethylaminoethyl methacrylate (MADAME); diethylaminoethyl methacrylate (DEAMEA); dimethylaminopropylacrylamide; and the salts thereof.

29. Copolymer according to claim 27, in which the anionic monomers are chosen from acrylic acid, methacrylic acid, crotonic acid, maleic anhydride, itaconic acid, fumaric acid, maleic acid , sytrenesulfonic acid, acrylamidopropanesulfonic acid, vinylbenzoic acid, vinylphosphonic acid, and the salts thereof.

30. Copolymer according to claim 27, in which the nonionic monomers are chosen from:

- The hydroxyalkyl (meth) acrylates have the alkyl group a of 2 to 4 carbon atoms, in particular hydroxyethyl (meth) acrylate;

- vinyllactams; - methacrylamide and N-alkyl (Ci to C) -

(meth) acrylamides such as isobutylacrylamide; (meth) acrylates of polysaccharides such as sucrose acrylate.

31. Copolymer according to any one of claims 1 to 30, chosen from bisquenced copolymers, triblock copolymers and polyblock copolymers having more than three blocks.

32. The copolymer according to claim 31, which is a polysequence copolymer, in which one or two blocks have a Tg less than or equal to 20 ° C and the other blocks have a Tg greater than 20 ° C and less than 20 ° C.

33. Cosmetic composition comprising the copolymer according to any one of claims 1 to 32.

34. Cosmetic composition according to claim 33, containing from 0.1 to 60% by weight, preferably from 5% to 50% by weight, and more preferably from 1 to 40% by weight of the copolymer.

35. Composition according to any one of claims 33 and 34, comprising, in addition to said copolymer, a physiologically acceptable medium, in which the copolymer is in dissolved or dispersed form.

36. Composition according to any one of claims 33 to 35, wherein the physiologically acceptable medium comprises one or more suitable solvents forming a hydrophilic phase chosen from water and mixtures of water and ^'solvent (s) organic ( s) hydrophilic, such as alcohols and in particular lower monoalcohols linear or branched having from 2 to 5 carbon atoms such as ethanol, isopropanol or n-propanol, and polyols such as glycerin, diglycerin, propylene glycol, sorbitol, pentethylene glycol, and polyethylene glycols .

37. Composition according to claim 36, in which the hydrophilic phase additionally contains C ₂ ethers and hydrophilic C ₂ to C aldehydes.

38. Cosmetic composition according to any one of claims 33 to 37, in which said physiologically acceptable medium further comprises a fatty phase composed of fatty substances liquid or solid at room temperature, of animal, vegetable, mineral or synthetic origin. .

39. Composition according to any one of claims 33 to 38, further comprising one or more cosmetically acceptable organic solvents.

40. Cosmetic composition according to any one of claims 33 to 39, in which said physiologically acceptable medium further comprises one or more auxiliary film-forming agents chosen from plasticizing agents and coalescing agents.

41. Cosmetic composition according to any one of claims 33 to 40, comprising, in addition, one or more coloring matters chosen from water-soluble dyes, and pulverulent coloring matters, such as pigments, nacres and flakes.

42. A composition according to any one of claims 33 to 41, further comprising fillers.

43. Cosmetic composition according to any one of claims 33 to 42, further comprising, ^one or more ingredient (s) commonly used (s) in cosmetics, such as vitamins, thickeners, trace elements, softeners, sequestrants, perfumes, basifying or acidifying agents, preservatives, sunscreens, surfactants, antioxidants, anti-hair loss agents, dandruff agents, propellants, or mixtures thereof.

44. Cosmetic composition according to any one of claims 33 to 43, characterized in that it is in the form of a suspension, dispersion, solution, gel, emulsion, in particular oil-in-water emulsion ( O / W) or water-in-oil (W / O), or multiple (W / O / W or polyol / O / W or O / W / O), in the form of cream, paste, foam, dispersion of vesicles, in particular of lipids "ionic or not, of two-phase or multiphase lotion, of spray, of powder, of paste, in particular of flexible paste or of anhydrous paste.

45. Cosmetic composition according to any one of claims 33 to 44, characterized in that it is a hair product, such as a hairspray or a shampoo.

46. Cosmetic composition according to any one of claims 33 to 44 ', characterized by the fact that it is a makeup composition, such as a nail polish.

47. Cosmetic method for making up or caring for keratin materials comprising the application to the keratin materials of a cosmetic composition according to one of claims 33 to 46.

48. Use of the copolymer according to any one of claims 1 to 32, to improve the styling power and the hold of a hair spray.

49. Use according to any one of claims 1 to 32, for increasing the adhesion of a nail varnish.

50. Use according to any one of claims 1 to 32, for improving the hold, the adhesion, of a makeup composition.