EP1397417A1

EP1397417A1 - Method for synthesis of polymers with thiol functions

Info

Publication number: EP1397417A1
Application number: EP02740786A
Authority: EP
Inventors: Zofia Agnieszka Wilczewska; Mathias Destarac; Samir Zard; Chakib Kalai; Gérard Mignani; Hervé Adam
Original assignee: Rhodia Chimie SAS
Current assignee: Rhodia Chimie SAS
Priority date: 2001-05-04
Filing date: 2002-05-03
Publication date: 2004-03-17
Also published as: WO2002090424A1; KR20030081462A; US20040132961A1; US7396901B2

Abstract

The invention concerns a method for preparing polymers having at least a thiol function, comprising pyrolysis of at least a polymer having at least a function of formula (I), wherein: R1, R2, R3 and R4 are such as defined in the description.

Description

PROCESS FOR THE SYNTHESIS OF THIOL-FUNCTIONAL POLYMERS

The present invention relates to a new process for the preparation of polymers having thiol ends from polymers with controlled architecture carrying particular xanthate functions, in particular resulting from a living or controlled radical polymerization process.

Polymers having thiol ends can find numerous fields of application. Thus, in cosmetics, they can be used in the hair field (such as, in the field of perms for the hair). They can also be used to generate organized layers of polymers on noble metallic substrates, such as gold. In addition, taking into account the reactivity of the thiol functions, the polymers thus obtained allow access to other polymer compounds, in particular by nucleophilic substitution or by radical addition of these functions.

Polymers with controlled architecture can be polymers (homopolymers) or copolymers (statistics, diblocks, triblocks, grafted or star, or hyperbranched). More specifically, within the meaning of the invention, the term "polymer with controlled architecture" means a polymer based on two or more monomers having a controlled arrangement of these different monomer units constituting it.

Polymers with controlled architecture are usually prepared by living ionic polymerization. This type of polymerization has the disadvantage of only allowing the polymerization of certain types of apolar monomers, in particular styrene and butadiene, and of requiring a particularly pure reaction medium and temperatures often below ambient so as to minimize the parasitic reactions, hence severe implementation constraints.

The radical polymerization has the advantage of being easily carried out without ^" excessive ^" purity conditions being observed and at temperatures equal to or above ambient. However, up to recently, there has not been a radical polymerization process making it possible to obtain polymers with controlled architecture, in particular block copolymers. Recently, a new radical polymerization process has developed: it is called "controlled" or "living" radical polymerization (Matyjaszewski, K., Ed. Controlied Radical Polymerization; ACS Symposium Series 685; American Chemical Society : Washington, DC, 1998, and ACS Symposium Series 768, 2001). In these systems, reversible termination or transfer reactions make it possible to maintain the active ends throughout the polymerization, consequently giving access to various polymers with controlled architecture.

Controlled radical polymerization ideally has the following distinctive aspects:

1. the number of chains is fixed throughout the duration of the reaction,

2. the chains all grow at the same speed, which results in: - a linear increase in molecular weights with conversion,

- a narrower mass distribution,

3. the average molecular weight is controlled by the monomer / chain precursor molar ratio,

4. the possibility of preparing block copolymers. The controlled nature is all the more marked when the rate of reactivation of the radical chains is very high compared to the rate of chain growth (propagation). There are cases where this is not always true (ie the rate of reactivation of radical chains is less than the rate of propagation) and conditions 1 and 2 are not observed, however, it is always possible to prepare block copolymers.

Recently, methods of living radical polymerization by reversible transfer by addition-fragmentation have been developed. This particular type of polymerization constitutes one of the most suitable technologies for synthesizing block copolymers by the radical route. In this context, the xanthates RSC = SOR 'have been used as transfer agents in patent applications WO 98/58974, WO 00/75207 and WO 01/042312 of the Rhodia Chimie company to synthesize polymers with controlled architecture. A process for the preparation by radical polymerization under thermal activation of hybrid silicone and organic copolymers has also been described in French patent application FR 00 09722 filed by the applicant on July 25, 2000. These hybrid copolymers are prepared from a silicone precursor having reactive functions, in particular of the xanthate type, of at least one ethylenically unsaturated organic monomer and of a radical polymerization initiator. It has also been described in French patent application No. 01 05144 filed by the applicant on April 13, 2001 a process for the preparation of star-shaped polymers which comprises a step of radical polymerization of a composition comprising: at least one crosslinking monomer, a source of free radicals and at least one first generation polymer. This first generation polymer is itself obtained by a process comprising a radical polymerization step reacting at least one crosslinking monomer, a source of free radicals and at least one transfer agent, in particular the xanthates of formula RSC = SOR ', as described in patent applications WO 98/58974, WO 00/75207 and WO 01/042312.

However, despite the advantages provided by these living radical polymerization processes, the polymers thus prepared have reactive ends, such as in particular xanthate functions, which are fragile because they are hydrolysable in basic medium. They are therefore capable of releasing sulfur by-products, of low molecular weight, smelly, and / or toxic for the environment and human beings.

In the following description, the term polymer is used to describe homopolymers or copolymers, unless otherwise indicated.

In addition, the term “block polymer” is understood to mean a copolymer comprising at least two successive sequences of blocks of monomer units of different chemical constitutions. The blocks can consist of a homopolymer or a polymer obtained from a mixture of ethylenically unsaturated monomers. In this case, the block can be a random copolymer. The block copolymer can comprise two blocks each made up of random copolymers. In this case, the ethylenically unsaturated monomers are such that the blocks obtained are of different natures. By different natures is meant blocks made up of monomers of different types, but also blocks made up of monomers of the same type but in different quantities.

An object of the present invention is to propose a simple implementation process, but effective, making it possible to remove the xanthatic functions carried by polymers, generally obtained by radical polymerization.

Another object of the invention is to propose a new access route to polymers with thiol functions. These aims and others which will appear on reading the description are achieved by the present invention which relates to a process for the preparation of polymers having at least one thiol function, which comprises the pyrolysis of at least one polymer having at least one function of formula (1) below:

(1)

formula (1) in which R1, R2, R3 and R4, identical or different, represent a group chosen from the hydrogen atom, alkyl, acyl, aryl, aralkyl, alkene or alkyne, cycloalkyl or heterocycloalkyl, saturated or no, aromatic, or a polymer chain, R1 and R4 or R1 and R2 which can form together a cycloalkyl or a heterocycloalkyl.

The pyrolysis temperature used in the process according to the invention depends to a large extent on the chemical nature of the radicals R1, R2, R3 and R4. This pyrolysis temperature is chosen so that there is transformation of the function of formula (1) presented by the polymers used into a thiol function and of producing carbonyl sulfide, of formula COS, and an olefinic compound. of formula (2) below: R1 R2 = R3R4. Thus, it is within the capacity of those skilled in the art to define the polymerization conditions so that the pyrolysis reaction does not take place during this polymerization. To give an order of magnitude, the pyrolysis temperature is generally between 20 and 200 ° C, preferably between 100 and 180 ° C, more particularly between 130 and 160 ° C. The pyrolysis according to the invention is generally carried out at atmospheric pressure.

The pyrolysis according to the invention is generally carried out on a polymer which is in solution, in emulsion (in the form of latex), solid or in the molten state. Thus, when it is used on a polymer which is in solution, the solvent is preferably a solvent having a boiling point greater than or equal to the pyrolysis temperature. Mention may in particular be made of water, an organic solvent, such as in particular 1, 2-dichlorobenzene.

The optionally substituted alkyl, acyl, aryl, aralkyl or alkyne groups generally have 1 to 20 carbon atoms, preferably 1 to 12, and more preferably 1 to 9 carbon atoms. They can be linear or branched. They can also be substituted by oxygen atoms, in the form in particular of esters, sulfur or nitrogen atoms.

Among the alkyl radicals, mention may in particular be made of the methyl, ethyl, propyl, butyl, pentyl, isopropyl, tert-butyl, pentyl, hexyl, octyl, decyl or dodecyl radical. Methyl or ethyl radicals are preferred.

The alkyne groups are radicals generally of 2 to 10 carbon atoms, they exhibit at least one acetylenic unsaturation, such as the acetylenyl radical. The acyl group is a radical generally having from 1 to 20 carbon atoms with a carbonyl group. Among the aryl radicals, mention may in particular be made of the phenyl radical, optionally substituted in particular by a nitro or hydroxyl function.

Among the aralkyl radicals, mention may in particular be made of the benzyl or phenethyl radical, optionally substituted in particular by a nitro or hydroxyl function.

The cycloalkyl radical (C ₃ -C ₈ ) is a cyclic hydrocarbon radical, such as in particular cyclopropyl, cyclopentyl or cyclohexyl. Preferably, when R1 and R4 or R1 and R2 form a cycloalkyl, this is cyclohexyl.

The heterocycloalkyl radical is a cycloalkyl radical as defined above containing, in place of one or more carbon atoms of the ring, one or more heteroatoms chosen from N, O and S.

Among the heterocycloalkyl radicals, mention may therefore be made in particular of the piperidyl, pyrazolidinyl, piperazinyl and morpholinyl radical.

When R1, R2, R3 or R4 is a polymer chain, this polymer chain can come from a radical or ionic polymerization or from a polycondensation.

R1, R2, R3 and R4 are preferably chosen in such a way that the elimination of the olefinic compound of formula (2) produced, indicated above, in particular by evaporation or steam entrainment, is made easier. Preferably, R1, R2, R3 and R4 represent groups chosen from among: the hydrogen atom, the methyl and ethyl radicals and the cyclohexyl radical for R1 and R4 or R1 and R2.

The polymer having at least one function of formula (1) used in the process of the present invention is preferably an organic polymer, a silicone type polymer or a hybrid copolymer on the one hand formed by a silicone type polymer and on the other hand by an organic polymer.

These polymers can be obtained by radical and / or ionic polymerization. Indeed, even if it was initially a question of withdrawing reactive functions obtained during a process for the synthesis of polymers by the radical route, it turns out that the process according to the invention also applies to polymers such than silicone polymers having at least one function of formula (1). According to a particular embodiment, to present at least one end of formula (1), the polymers used in the present invention were obtained by a process, as described in one of patent applications WO 98/58974 and WO 00 / 75207 from the company Rhodia Chimie, using at least one xanthate compound of formula (2) below:

(2) in which R, R1, R2, R3 and R4, identical or different, have the meanings given for R1, R2, R3 and R4 and specified above.

Thus, the polymers used in the process of the invention may for example be polymers resulting from a controlled radical polymerization process carried out by bringing one or more ethylenically unsaturated monomer (s) into contact, at least at least one source of free radicals and at least one xanthate reversible transfer agent of formula (2). More specifically, the living organic polymers used in the process of the invention can be block polymers resulting from a copolymerization process comprising N successive stages of radical polymerizations (N being greater than or equal to 2), the first of these stages being a controlled radical polymerization carried out by bringing into contact one or more ethylenically unsaturated monomer (s), at least one source of free radicals and at least one reversible transfer agent of the aforementioned type, and the (N-1) following stages being controlled radical polymerizations carried out by bringing into contact of one or more ethylenically unsaturated monomer (s) different from those of the preceding stage, of at least one source of free radicals and the living polymer composition from the previous step.

For example, when N is equal to 2, the polymer used in the present invention can be a polymer of formula (I) below:

(L)

, with m and n, identical or different, greater than or equal to 1, preferably greater than 6, and preferably less than 500, one of the two (m or n) possibly being equal to 0, when m or n> 1 the repeating unitary patterns of index m or n respectively are different or advantageously identical,

R, R1, R2, R3 and R4, identical or different, have the meanings given above for R1, R2, R3 and R4,

- V, V, W and, identical or different, represent: H, an alkyl group or a halogen, - X, X ', Y and Y', identical or different, represent H, a halogen or a group R ₅ , OR ₅ , O2COR5, NHCOH, OH, NH2, NHR ₅ , N (R ₅ ) 2, (R ₅ ) 2N ⁺ 0-, NHCOR ₅ , CO ₂ H, CO ₂ R ₅ , CN, CONH ₂ , CONHR ₅ or CON (Rs) 2, in which R ₅ is chosen from alkyl, aryl, aralkyl, alkylaryl, alkene or organosilyl groups, optionally perfluorinated and optionally substituted by one or more carboxyl, epoxy, hydroxyl, alkoxy, amino, halogen or sulfonic groups, and

- a and b are 0 or 1.

The polymer having at least one function of formula (1) used in the present invention may correspond to a star-shaped polymer. Thus, it can be obtained by a process as described in French patent application No. 01 05144 filed by the applicant on April 13, 2001. This process comprises a step of radical polymerization of a composition comprising: at least one crosslinking monomer, a source of free radicals and at least one first generation polymer. This first generation polymer is itself obtained by a process comprising a radical polymerization step reacting at least one ethylenically unsaturated monomer, a source of free radicals and at least one xanthate compound of formula (2) as previously described.

The crosslinking monomers are chosen from organic compounds comprising at least two ethylenic unsaturations and at most 10 unsaturations and known to be radically reactive. Preferably, these monomers have two ethylenic unsaturations.

Thus, mention may in particular be made of acrylic, methacrylic, acrylamido, methacrylamido, vinyl ester, vinyl ether, diene, styrene, alpha-methyl styrene and allyl derivatives. As crosslinking monomers, N, N'-methylenebisacrylamide, divinylbenzene and ethylene glycol diacrylate are preferred. The polymer having at least one function of formula (1) used in the present invention can correspond, according to another embodiment, to silicone and organic hybrid copolymers comprising units (II):

A _x U _y SiO [4_ ( _x + y)] / 2 (II) in which:

- x is equal to 0, 1, 2 or 3, y is equal to 0, 1, 2 or 3 with 2 <(x + y) <3 and y is different from 0 for at least one of the units of the hybrid copolymer,

• the symbols A, identical or different, represent:

a linear or branched alkyl radical containing 1 to 8 carbon atoms, optionally substituted by at least one halogen, preferably fluorine, the alkyl radicals preferably being methyl, ethyl, propyl, octyl and 3,3,3-trifluoropropyl,

^• a cycloalkyl radical containing between 3 and 8 ring carbon atoms, optionally substituted, ^• an aryl radical containing between 6 and 12 carbon atoms which may be substituted, preferably phenyl or dichlorophenyl,

^• _. an aralkyl part having an alkyl part containing between 5 and 14 carbon atoms and an aryl part containing between 6 and 12 carbon atoms, optionally substituted on the aryl part by halogens, alkyls and / or alkoxyls containing 1 to 3 atoms of carbon, the symbols U, identical or different, represent (III):

(III) in which:

- R1, R2, R3 and R4, identical or different, have the meaning given above,

- V and V, identical or different, have the meanings given above,

- X and X ', identical or different, have the meanings given above,

- R ² and R ³ , identical or different, represent:

- an optionally substituted alkyl, acyl, aryl, alkene or alkyne group (i),

- a carbon (saturated or unsaturated, optionally substituted and / or aromatic) cycle (ii)

- a heterocycle (iii), saturated or not, optionally substituted, - a hydrogen atom, groups: alkoxycarbonyl,

5 ^~ aryloxycarbonyl (-COOR), carboxy (-COOH), acyloxy (-O2CR),

5 carbamoyl (-CONR 2), cyano (-CN), alkylcarbonyl, alkylarylcarbonyl, arylcarbonyl, arylalkylcarbonyl, phthalimido, maleimido, succinimido, amidino, guanidimo, hydroxy (-OH), amino (-

5 5

NR 2). halogen, allyl, epoxy, alkoxy (-OR),

S-alkyl, S-aryl, groups having a hydrophilic or ionic character such as the alkali salts of carboxylic acids, the alkali salts of sulfonic acid, the alkylene oxide chains (POE, POP), the cationic substituents ( quaternary ammonium salts),

5 R, identical or different, representing an alkyl or aryl group, and / or a polymer chain,

- the radicals (i), (ii) and (iii) which can be advantageously substituted by: substituted phenyl groups, substituted aromatic groups, or groups: alkoxycarbonyl, aryloxycarbonyl (-

COOR ⁵ ), carboxy (-COOH), acyloxy (-O2CR ⁵ ), carbamoyl (-

5 CONR 2) ₁ cyano (-CN), alkylcarbonyl, alkylarylcarbonyl, arylcarbonyl, arylalkylcarbonyl, phthalimido, maleimido, succinimido,

5 amidino, guanidimo, hydroxy (-OH), amino (-NR 2). halogen, allyl, epoxy, alkoxy (-OR), S-alkyl, S-aryl, groups having a hydrophilic or ionic character such as the alkali salts of carboxylic acids, the alkali salts of sulfonic acid, the polyoxide chains alkylene (POE, POP), cationic substituents (salts

5 of quaternary ammonium), R, identical or different, representing an alkyl or aryl group, and / or a polymer chain,

- W, identical or different, represent a divalent radical chosen from

-O-, -NR ₅ -, -NH-, -S-, R ₅ having the meaning given above,

- Sp, identical or different, represent a ball joint consisting of a divalent organic radical of formula - (CH ₂ ) _X - in which x 'is between 1 and 20, this radical possibly being substituted and / or containing at least one heteroatom , a = 0 or 1, m> 1, and when m> 1 the repeating unitary units of index m are identical or different, m being preferably less than 500.

These hybrid copolymers can be obtained by the process in which:

- at least one ethylenically unsaturated monomer of formula (IV):

CXX '(= CV - CV') _a = CH ₂ ,

- a precursor silicone compound comprising units, identical or different, of formula (V):

A _x U ' _y SiO [4_ (χ + y)] / 2 in which:

- A, x and y correspond to the values given above, and the monovalent radical U 'is according to the following formula (VI):

- and a radical polymerization initiator. The precursor silicone compound of general formula (V) used within the process for the preparation of these hybrid copolymers can be obtained by reaction:

(i) a silicone comprising units of formula (Vil):

R _x U "ySiO [4_ ( _{x + y} )] / 2 where the monovalent radical U" is according to the following formula (VIII):

in which :

- R ² , R ³ , W and Sp are definitions identical to those given above,

- L is an electrofuge group, for example: Br ^" , CI ^" , I ^" , OTs ^" , OMs ^" , (C ₆ H ₆ ) - (C = O) -O ^" , (CH ₃ ) - (C = O ) -O ^' , (CF ₃ ) - (C = O) -O ^' .

(ii) with a compound chosen from those of the following general formulas (IX), (X) or (XI):

in which :

^" R1, R2, R3 and R4, identical or different, have the meaning given above,

- M ' ⁺ represents K ⁺ , Na ⁺ , NR ⁺ , or PR ⁺ ' R being of definition similar to that given for R of formula (I),

- M " ²⁺ represents an alkaline earth metal such as Ca ²⁺ , Ba ²⁺ and Sr ^ ⁺⁺ , - M '"represents Zn, Cd, m is equal to 1 or 2, n is equal to 1, 2, 3 or 4 and preferably m is equal to 1 and n is equal to 2.

This silicone of formula (VII) can in particular be obtained from (i) of a silicone comprising units of formula (XII): R _x U "'ySiO [4_ (χ + y)] / 2 where the monovalent radical U '"is of formula (XIII): -Sp-WH and (ii) of a compound of formula:

In addition to hybrid copolymers comprising a single organic segment, the polymers used in the process according to the invention may correspond to hybrid polymers carrying organic block groups (that is to say multiblock). For this, their preparation process consists in repeating the implementation of the preparation process described above using:

- ethylenically unsaturated monomers different from the previous implementation, and

- In place of the precursor silicone compound (V), the hybrid copolymer comprising units (11) with blocks from the previous implementation. According to this process for preparing multiblock copolymers, when it is desired to obtain copolymers with homogeneous blocks and not with a composition gradient, and if all the successive polymerizations are carried out in the same reactor, it is essential that all the monomers used during one step has been consumed before the polymerization of the next step begins, therefore before the new monomers are introduced.

These hybrid copolymers have been described in French patent application FR 00 09722 filed by the applicant on July 25, 2000. As mentioned above, the polyhedron having at least one function of formula (1) can correspond, according to another embodiment, to a silicone type polymer. In this case, the silicone type polymer has the general formula (V), as described above.

The ethylenically unsaturated monomers mentioned previously are more specifically according to the invention the monomers chosen from styrene or its derivatives, butadiene, chloroprene, (meth) acrylic esters, vinyl esters, vinyl nitriles, vinyl esters and amides unsaturated carboxylic acids.

The following examples illustrate the invention without, however, limiting its scope.

EXAMPLES:

Example 1:.

- Synthesis of the sodium salt of O- (2-propyl) xanthic acid

1 equivalent of 2-propanol is added dropwise, at 0 ° C, to a solution (1 M) of 1.1 equivalent of NaH in THF. 4 equivalents of CS ₂ are added, and the reaction medium is stirred for 1 night at room temperature. The THF is then evaporated, 1 liter of petroleum ether is then added to wash the solid obtained, by filtration. The solid is then dried under vacuum. NMR Η

5.45 ppm (sext. 1 H (2)); 1.84 and 1.62 ppm (mult. 2x1 H (3)); 1.32 ppm (double 2H (1)); 0.93 ppm (trip. 3H (4))

¹³ C NMR

208.0 ppm C (5); 81.5 ppm C (2); 28.8 ppm C (3); 19.0 ppm C (1); 10.0 ppm C (4)

- Synthesis of a silicone oil (polydimethylsiloxane, DPn = 14) α, ω-bis [O- (2-propyl)] xanthate

To a solution of 10 g of α, ω-hydroxylated silicone oil (polydimethylsiloxane, DPn = 14) (1 equivalent) and 2.6 g (4 equivalents) of pyridine in ether (200 ml), is added dropwise and at room temperature, 1.9 ml (2.4 equivalents) of 2-bromo-propionyl bromide.

After stirring overnight at room temperature, 50 ml of water are added to the reaction mixture. The aqueous phase is then extracted with 2 x 100 ml of ethyl acetate. The combined organic phases are then washed successively with an aqueous NaOH solution (1 M), a 10% aqueous HCl solution, water and brine, then dried over magnesium sulfate. The solvents are then evaporated. The crude product obtained is then chromatographed on a silica column (heptane 9 / ether 1) to give 11 g of brominated silicone oil. 1 g of the brominated silicone oil is added to a solution of 0.5 g of xanthate 1 (4 eq.) Dissolved in 10 ml of CH ₃ CN. The reaction mixture is stirred overnight for 1 night at room temperature. The solvent is evaporated, ether is then added, then filtration is carried out to remove the excess xanthate salt and the sodium salt formed. On the spectrum of the crude product obtained, the bromine is completely displaced by the xanthate salt.

¹ H NMR

5.56 ppm (2H (2 ') sext.); 4.32 ppm (quad. 2H (5)); 4.06 ppm (trip. 4H (3)); 1.6 to 1.8 ppm (mult. 8H (2, 3 ')); 1.51 ppm (doub. 6H (6)); 1.30 ppm (mult. 6H (1 ')); 0.90 ppm (trip. 6H (4 ')); 0.52 ppm (mult. 4H (1)); 0.1 ppm (mult. SiMe ₃ )

³ C NMR

211.5 ppm C (5 '); 171.4 ppm C (4); 82.7 ppm C (2 '); 68.1 ppm C (3); 46.9 ppm C (5); 28.5 ppm C (3 '); 22.6 ppm C (2); 18.7, 17.0 and 9.6 ppm C (1 '), C (4') and C (6); 14.2 ppm C (1); 1.0 and 0.1 ppm (Si-CH ₃ ).

Synthesis of PDMS oil (polydimethylsiloxane, DPn = 14) α, ω-bisthioI

0.2 g of silicone carrying the xanthate 2 function is dissolved in 1 ml of chlorobenzene, then refluxed. After 2 hours of stirring, little change is observed.

In solution in dichlorobenzene, the 0.2 g of silicone 2 are refluxed for 2 hours. The solvent is then evaporated with the elimination products, to give a crude product where the signals characteristic of the xanthate function are no longer observed by ¹ H and ¹³ C NMR.

On the other hand, ¹ H NMR is still observed, 1 signal at 3.5 ppm, which should correspond to the H (5). The chemical displacement of the corresponding carbon at ¹³ C confirms the same thing.

1 H NMR

4.09 ppm (trip doubl. 4H (3)); 3.50 ppm (mult. 2H (5)); 1.72 ppm (mult. 4H (2)); 1.50 ppm (doub. 6H (2)); 0.55 ppm (mult. 4H (1)); 0.1 ppm (mult. SiMe ₃ )

¹³ C NMR

68.0 ppm C (3); 48.2 ppm C (5); 22.7 ppm C (2); 17.0 ppm C (6); 14.1 ppm C (1); 1, 1 and 0.2 ppm (Si-CH ₃ ).

Claims

1. Process for the preparation of a polymer having at least one thiol function, which comprises the pyrolysis of at least one polymer having at least one function of formula (1) below:

(1)

2. Method according to claim 1, characterized in that the pyrolysis temperature is between 20 and 200 ° C, preferably between 100 and 180 ° C, more particularly between 130 and 160 ° C.

3. Method according to claim 1 or 2, characterized in that the pyrolysis is carried out on a polymer in solution, in emulsion or in the molten state.

4. Method according to claim 3, characterized in that the solvent is chosen from water and an organic solvent, such as in particular 1, 2-dichlorobenzene.

5. Method according to one of the preceding claims, characterized in that R1, R2, R3 and R4 represent groups chosen from: the hydrogen atom, the methyl, ethyl radical and the cyclohexyl radical for R1 and R4 or

R1 and R2.

.

6. Method according to one of the preceding claims, characterized in that the polymer having at least one function of formula (1) is a polymer organic, a silicone type polymer or a hybrid copolymer on the one hand formed by a silicone type polymer and on the other hand by an organic polymer.

7. Method according to one of the preceding claims, characterized in that the polymer having at least one function of formula (1) is a polymer of formula (I) below:

O)

, with m and n, identical or different, greater than or equal to 1, preferably greater than 6, one of the two (m or n) possibly being equal to 0, when m or n> 1 the repeating unitary patterns of index m or n respectively are different or advantageously identical, R, R1, R2, R3 and R4, identical or different, have the meanings given for R1, R2, R3 and R4 in claim 1, V, V, W and W ' , identical or different, represent: H, an alkyl group or a halogen,

X, X ', Y and Y', identical or different, represent H, a halogen or a group R ₅₎ OR ₅ , O2COR5, NHCOH, OH, NH ₂ , NHR ₅ , N (R ₅ ) 2, (R ₅ ) 2N ⁺ O-, NHCOR5, CO ₂ H, C0 ₂ R ₅ , CN, CONH ₂ , CONHR5 or CON (Rs) 2 _> in which R ₅ is chosen from alkyl, aryl, aralkyl, alkylaryl, alkene or organosilyl groups , optionally perfluorinated and optionally substituted by one or more carboxyl, epoxy, hydroxyl, alkoxy, amino, halogen or sulfonic groups, and - a and b are 0 or 1.

8. Method according to one of the preceding claims 1 to 6, characterized in that the polymer is a hybrid silicone and organic copolymer comprising units (11):

AχUySiO [4_ (χ ₊ y)] / 2 (H) in which:

- x is equal to 0, 1, 2 or 3, y is equal to 0, 1, 2 or 3 with 2 <(x + y) ≤ 3 and y is different from 0 for at least one of the units of the hybrid copolymer,

• the symbols A, identical or different, represent:

^• a linear or branched alkyl radical containing 1 to 8 carbon atoms, optionally substituted with at least one halogen, preferably fluorine, the alkyl radicals preferably being methyl, ethyl, propyl, octyl and 3,3,3-trifluoropropyl,

^• a cycloalkyl radical containing between 3 and 8 ring carbon atoms, optionally substituted, - an aryl radical containing between 6 and 12 carbon atoms which may be substituted, preferably phenyl or dichlorophenyl,

^• an aralkyl part having an alkyl part containing between 5 and 14 carbon atoms and an aryl part containing between 6 and 12 carbon atoms, optionally substituted on the aryl part by halogens, alkyls and / or alkoxyls containing 1 to

3 carbon atoms,

• the symbols U, identical or different, represent (III): - (CV = CV) a - CH ₂ C (R ² R ³ ) - (C = 0) -W-Sf:

(III) in which:

- R1, R2, R3 and R4, identical or different, have the meaning given in claim 1,

- V and V, identical or different, have the meanings given in claim 6,

- X and X ", identical or different, have the meanings given in claim 6,

- R ² and R ³ , identical or different, represent:

- an optionally substituted alkyl, acyl, aryl, alkene or alkyne group (i),

- a heterocycle (iii), saturated or unsaturated, optionally substituted, a hydrogen atom, alkoxycarbonyl, aryloxycarbonyl (-COOR), carboxy (-COOH), acyloxy (-O2CR) groups,

5 carbamoyl (-CONR 2). cyano (-CN), alkylcarbonyl, alkylarylcarbonyl, arylcarbonyl, arylalkylcarbonyl, phthalimido, maleïmido, succinimido, amidino, guanidimo, hydroxy (-OH), amino (-

NR 2). halogen, allyl, epoxy, alkoxy (-OR),

S-alkyl, S-aryl, groups having a hydrophilic or ionic character such as the alkali salts of carboxylic acids, the alkali salts of sulfonic acid, the alkylene oxide chains (POE,

POP), cationic substituents (quaternary ammonium salts), 5 R, identical or different, representing an alkyl or aryl group, and / or a polymer chain,

COOR ⁵ ), carboxy (-COOH), acyloxy (-O2CR ⁵ ), carbamoyl (-

5 CONR 2). cyano (-CN), alkylcarbonyl, alkylarylcarbonyl, arylcarbonyl, arylalkylcarbonyl, phthalimido, maleïmido, succinimido,

- W, identical or different, represent a divalent radical chosen from,

-O-, -NR ₅ -, -NH-, -S-, R ₅ having the meaning given in claim 4,

- Sp, identical or different, represent a ball joint consisting of a divalent organic radical of formula - (CH ₂ ) _X - in which x 'is between 1 and 20, this radical possibly being substituted and / or containing at least one heteroatom ,

- a = O or 1,

- m> 1, and when m> 1 the repeating unitary patterns of index m are identical or different.

9. Method according to one of claims 1 to 6, characterized in that the polymer having at least one function of formula (1) is a silicone type polymer of formula (V):

AχU'ySiO [4_ ( _{χ +} y)] / 2 in which :

.- A, x and y correspond to the values given in claim 8, and the monovalent radical U 'is according to the following formula (VI):

- s. -CR ² R ³ - (C = 0) -W-Sp.

in which

- R1, R2, R3 and R4, identical or different, have the meaning given in claim 1, - R ² and R ³ , W and Sp, identical or different, have the meanings given in claim 8.

10. Method according to one of claims 1 to 6, characterized in that the polymer having at least one function of formula (1) is a star-shaped polymer.