Method for free radical reduction of dithiocarbonylated or dithiophosphorylated functions borne by a polymer

METHOD FOR RADICALALLY REDUCING DITHIOCARBONYL OR DITHIOPHOSPHORYLATED FUNCTIONS CARRIED BY A POLYMER

The present invention relates to a process for the radical reduction of dithiocarbonyl or dithiophosphorylated functional groups carried by a polymer resulting from a living radical polymerization, giving in particular access to polymers with a controlled architecture, and in particular to block copolymers, not exhibiting such dithiocarbonyl or dithiophosphorylated functions.

In the present description, in the absence of contrary indications, the term "polymer" will be used to designate, in the broad sense, both homopolymers and copolymers. The polymers can correspond to polymers (homopolymers) or copolymers (statistics, diblocks, triblocks, grafted or star, or hyperbranched)

More specifically, within the meaning of the invention, the term "polymer architecture controlled" a polymer based on two or more monomers having a controlled arrangement of these different monomer units constituting it.

By "block polymer" (or "block copolymer") is meant to designate, according to the invention, a copolymer comprising at least two successive sequences (blocks) of monomeric units of different chemical constitutions. Each of the blocks present may consist of a homopolymer or a copolymer obtained from a mixture of ethylenically unsaturated monomers. In the second case, the block can in particular be a random copolymer. Block copolymers within the meaning of the invention may thus comprise two blocks each consisting of random copolymers. In this case, the ethylenically unsaturated monomers are such that the blocks obtained are of different natures. By "blocks of different natures" is meant either blocks made up of monomers of different types, either blocks made of monomers of the same type but in different amounts. Controlled architecture polymers, such as block polymers, are usually prepared by ionic polymerization. This type of polymerization, however, has the disadvantage of only allowing the polymerization of certain types of apolar monomers, such as styrene and butadiene. In addition, the ionic polymerization generally requires severe implementation stresses, and in particular a reaction medium that is particularly free of impurities and temperatures that are often used below ambient, so as to minimize the appearance of parasitic reactions. . Such constraints do not exist in the case of radical polymerization, which also has the advantage of being able to be implemented in the context of the polymerization of other types of monomers. As a result, radical polymerization was quickly considered in the context of the preparation of controlled-architecture polymers of the type of block copolymers.

However, in a conventional radical polymerization reaction, the growing macroradicals generally have non-selective reactivity and the chains generally terminate irreversibly by coupling or disproportionation. Consequently, in radical polymerization, it is generally very difficult to control the structure of the chains produced and it is in particular extremely difficult to produce end-functionalized polymers, which limits, in the most general case, the possibilities of to obtain block copolymers.

In order to overcome this type of difficulty, particular radical polymerization processes have recently been developed in which the growing polymer chains as well as the chains produced in fine are functionalized by terminal groups that can be reactivated in the form of free radicals. through termination reactions or reversible transfers. This type of specific radical polymerization is generally referred to as "controlled" or "living" radical polymerization. These denominations come from the fact that the presence of the reactivatable terminal groups described above induces the existence of equilibria between functionalized species (so-called "dormant" species) and active species (free radicals), this makes it possible both to control the growth of the polymer chains (obtaining tight mass distributions and control of the average molecular weight, in particular by adjusting the monomer / precursor molar ratio of active chains) and to obtain functionalized polymers, so-called "living", that is to say capable of being implemented as reactivatable species in subsequent radical polymerization reactions, which proves particularly interesting in the context of the preparation of block copolymers. For further details on this subject, reference may be made to K. atyjaszewski, Ed. Controlled Radical Polymerization, ACS Symposium Series 685, American Chemical Society Washington, DC, 1998 and ACS Symposium Series 768, 2001.

Live (or controlled) radical polymerization ideally has the following distinctive aspects:

1. a fixed number of chains throughout the duration of the reaction; 2. a very narrow growth rate around a mean value, for all the growing polymer chains, and advantageously an identical growth rate for all the chains, which results in:

an increase in the molecular masses with the conversion, advantageously in a linear manner; and

- a narrow mass distribution;

3. a possibility of controlling the average molecular weight by the mole ratio monomer / chain precursor; In this context, in particular, we have developed multiple methods of controlled polymerizations (living), known as "reversible chain transfer", implementing mechanisms of addition-fragmentation. This particular synthesis of polymer is carried out by carrying out a radical polymerization in the presence of reversible transfer agents and a source of free radicals, generally thermally initiated, which leads to the production of functionalized polymers. This type of polymerization is one of the most appropriate technologies for synthesizing radical block copolymers.

For more information concerning this type of reversible addition-fragmentation transfer polymerizations, reference may be made, for example, to the patent applications WO 98/01478 or WO 99/35178, which describe the use of reversible transfer agents of the following type. dithioesters of RS (C = S) R 'type for the synthesis of copolymers with controlled architecture. The use of RS-type dithiocarbamate transfer agents (C = S) NR'R "to carry out the control of radical polymerizations has also been described in patent applications WO 99/35177 or WO 99/31144. regarding this type of reversible transfer polymerization, a process for the preparation by radical polymerization under thermal activation of hybrid silicone / organic copolymers has also been described in the French patent application FR 00/09722 filed by the Applicant on July 25, 2000. These hybrid copolymers consist of a silicone skeleton and carriers of organic groups, they are prepared from a silicone precursor, at least one organic ethylenically unsaturated monomer and a radical polymerization initiator. In the context of the living radical polymerization by thermal initiation, the xanthates of general formula RSC (= S) OR ', described for example in patent applications WO 98/58974, WO 00/75207 and WO 01/042312 are agents particularly interesting reversible transfer, which make it possible to control the radical polymerization of a large number of monomers such as styrene monomers, acrylic monomers, acrylamide monomers, vinyl ester monomers and diene monomers. Whatever the exact mode of implementation of a living radical polymerization reaction, the polymer chains obtained at the end of such a reaction are most often functionalized at the end of the chain. This functionalization generally confers on them an actual "living" character, that is to say that they can act as reactivatable species in subsequent polymerization reactions, which proves particularly advantageous for the synthesis of architectural polymers. controlled, and in particular of block copolymers. However, as a rule, the reactivable functions present at the end of chains on the polymers obtained at the end of a living radical polymerization are also fragile, and they are for example often hydrolysable in basic medium. These hydrolysis reactions are likely to release by-products of low molecular weight, malodorous and / or toxic to the environment and to the human being, such as, for example, carbonyl sulphide in the case of polymers having reactivatable functions. xanthate type.

One of the aims of the present invention is to provide a method for removing the reactive functions carried by certain polymers resulting from a living polymerization reaction.

The object of the invention is also to propose a process for the preparation of polymers having the advantages presented by the polymers resulting from a living radical polymerization reaction, namely, in particular, a well-controlled average molecular weight Mn and a distribution tightened masses, but not having functions reactivable at the end of chains likely to lead to the aforementioned drawbacks. These objects, and others which will become apparent from the description, are achieved by the present invention, which relates to a process for preparing a polymer, which comprises a step of contacting:

(A) at least one living organic polymer having at the end of the chain at least one reactivatable dithiocarbonyl or dithiophosphorylated function; (B) at least one source of free radicals; and

(C) at least one organic compound carrying a labile hydrogen atom.

This step makes it possible more particularly to carry out a substitution of the dithiocarbony or dithiophosphorylated function present on said living organic polymer with a hydrogen atom.

For the purposes of the present description, the term "living organic polymer" means any polymer within the meaning of the invention, at least partially based on organic monomer units, and capable of being obtained by a living radical polymerization process. .

The living organic polymers which are used in the process of the invention may advantageously be copolymers with a controlled architecture, and may thus be, for example, block copolymers. Whatever their exact structure, these living organic polymers specifically have, at the end of the chain, at least one reactivatable function dithiocarbonylee or dithiophosphorylated, ie a function respectively of type -S (C = S) -R or -S (P = S) -R, where R denotes any organic group.

Thus, the reactivatable dithiocarbonyl or dithiophosphorylated function present at the chain end on the polymer (A) used in the process of the invention may advantageously be a -S (C = S) -R or -S (P = S) -R, where R is:

(i) an alkyl, haloalkyl, perfluoroalkyl, alkenyl or alkynyl, acyl, aryl, arylalkyl, arylalkenyl or arylalkynyl group, or a carbon ring or a heterocycle, or a polymer chain;

(ii) a radical -OR^atin which R^at denotes a group chosen from:

an alkyl, haloalkyl, perfluoroalkyl, alkenyl, alkynyl, acyl, aryl, arylalkyl, arylalkenyl or arylalkynyl group, or a carbon ring or a heterocycle, or a polymer chain;

- a group -CR^bR^cPO (OR^d)(GOLD^e), in which :

- R and R^c each independently of one another represents a hydrogen atom, a halogen atom, a perfluoroalkyl group, a carbon ring or a heterocycle, or a group -NO₂, -NCO, -CN, or a group chosen from groupings of the -R type^f, -SO₃R^f, -GOLD^f, -SR^f, -NR^fR^g, -OOCR^f, -CONR^fR⁹, or -SO₃R^f, in which R^f and R⁹ independently denote an alkyl, alkenyl, alkynyl, aryl, aryl, arylalkyl, arylalkenyl or arylalkynyl group; or R^b and R^c form together with the carbon to which it is attached, a C = O or C = S group, or a hydrocarbon ring or a heterocycle; and

- R^d and R^e each represent, independently of one another, a radical corresponding to one of the definitions given above for the group R^f ; or R^d and R^e together form a hydrocarbon chain containing from 2 to 4 carbon atoms, optionally interrupted by a -O-, -S-, or -NR group^h- where R^h meets one of the definitions given above for the group R^f ;

(iii) a grouping -NR'R^j, where: - R 'and R^J independently of one another represent a radical selected from an alkyl, haloalkyl, alkenyl, alkynyl, acyl, ester, aryl, arylalkyl, arylalkenyl, arylalkynyl, or a carbon ring; or - R 'and R^j together form a hydrocarbon chain comprising from 2 to 4 carbon atoms, optionally interrupted by a group -O-, -S-, or -NR^H- where R^H meets one of the definitions given above for the group R^f, said hydrocarbon-based chain advantageously forming a 5-membered ring with the nitrogen to which R 'and R are attached^j, the radicals R 'and R^j preferably inducing an electroattractant effect or a delocalization effect with respect to the electron density of the nitrogen atom to which they are bonded. Throughout the present description, it is meant to cover, by the term "alkyl" group, a linear or branched, saturated hydrocarbon radical which may optionally include one or more saturated aliphatic ring (s). Within the meaning of the invention, the alkyl groups can have up to 25 carbon atoms, and they preferably contain from 1 to 12 carbon atoms, and preferably from 1 to 6 carbon atoms.

In particular, an alkyl group may also designate, within the meaning of the invention, a cycloalkyl group, that is to say a cyclic saturated hydrocarbon radical, preferably having from 3 to 10 carbon atoms.

For the purposes of the invention, an "alkoxy" group refers to an -Oalk radical, where Alk denotes an alkyl group as defined above.

For the purposes of the invention, the term "haloalkyl" group is understood to mean an alkyl radical as defined above and substituted by at least one halogen atom, where the term "halogen atom" designates here, as in the case of the description, a fluorine, chlorine, bromine or iodine atom, preferably a fluorine or chlorine atom, and preferably a fluorine atom. The "haloalkyl" groups of the invention can thus be, for example, "perfluoroalkyl" groups, that is to say, within the meaning of the invention, groups corresponding to the formula -CH₂C_notF_{2n +}where n represents an integer ranging from 1 to 20. Moreover, an "alkenyl" group, in the sense used in the present description, denotes a linear or branched unsaturated hydrocarbon radical having at least one C double bond. = C. The alkenyl groups of the invention can have up to 25 carbon atoms and preferably comprise from 2 to 12 carbon atoms, and preferably from 2 to 6 carbon atoms.

Similarly, the term "alkynyl" group means an unsaturated hydrocarbon radical, linear or branched and having at least one C tripleC triple bond. The alkynyl groups of the invention generally have from 2 to 25 carbon atoms, and they preferably comprise from 2 to 15 carbon atoms, and preferably from 2 to 6 carbon atoms.

For the purposes of the invention, an "acyl" group denotes a group of formula -C (= O) -B, where B denotes a linear or branched, saturated or unsaturated hydrocarbon-based chain containing from 1 to 25 carbon atoms. carbon atoms, and which may in particular be an alkyl, alkenyl or alkynyl group as defined above.

By "ester" group within the meaning of the invention is meant a -C (= O) -OB group, where B denotes a linear or branched, saturated or unsaturated hydrocarbon-based chain containing from 1 to 25 carbon atoms, and which may in particular be an alkyl, alkenyl or alkynyl group as defined above.

For the purposes of the invention, a "carbon-based ring" radical denotes a saturated, unsaturated or aromatic cyclic group, in particular of cycloalkyl, cycloalkenyl or cycloalkynyl type, which is optionally substituted and which has from 3 to 20 carbon atoms. A "heterocycle" type radical refers to such a carbon ring interrupted by at least one heteroatom selected for example from N, O or S.

For the purposes of the invention, an "aryl" group refers to a mono- or polycyclic aromatic group generally having from 5 to 20 carbon atoms, and preferably from 6 to 10 carbon atoms. Thus, it can for example be a phenyl group, or else 1- or 2-naphthyl. According to one particular variant, an "aryl" group within the meaning of the invention can integrate one or more heteroatoms such as sulfur, oxygen, or nitrogen. In this particular case, the "aryl" group within the meaning of the invention denotes a mono- or polycyclic heteroaromatic group.

The "arylalkyl", "aralkenyl" and "aralkynyl" groups within the meaning of the invention are respectively alkyl, alkenyl and alkynyl chains substituted by an aryl group as defined above. In other words, the "arylalkyl", "aralkenyl" and "aralkynyl" groups within the meaning of the invention are respectively groups of the Ar-Ra-type, in which Ar- represents an aryl group and where the groups of type -Ra- represent an alkylene, alkenylene or alkynylene chain respectively.

The various radicals may optionally be interrupted by one or more heteroatoms chosen in particular from O, S, and N, Si, or by groups - (C = O) -, - (C = S) -, -SO₂-, -SO-, or secondary or tertiary amines, and they may be substituted by any type of groups not likely to interfere with the polymerization reaction or lead to parasitic reactions between the compounds in the presence, and especially by one or several identical or different groups chosen from a halogen atom, a silyl group, a group -OH, alkoxy, -SH, thioalkoxy, -NH₂, mono- or di-alkylamino, -CN, -COOH, ester, amine, or perfluoroalkyl, said substituents possibly being interrupted by heteroatoms. It is skilled in the art to choose the nature of the different groups and substituents present in the compounds used to avoid any unwanted side reaction.

Preferably, the living organic polymer (A) used in the process of the invention is a polymer resulting from a process using a living radical polymerization using dithioester-type addition-fragmentation reversible transfer agents. xanthate, dithiocarbamate, thioether-thione, trithiocarbonate or dithiophosphoroester, and which has at least one end of its chain a reactivatable part dithiocarbonylee or dithiophosphorylée from these reversible transfer agents.

The living organic polymers (A) used in the process of the invention may for example be polymers resulting from a controlled radical polymerization process carried out by contacting 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. More specifically, the living organic polymers used in the process of the invention may 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 the steps being a controlled radical polymerization carried out by contacting one or more ethylenically unsaturated monomer (s) with at least one source of free radicals and at least one reversible transfer agent of the aforementioned type, and the following (N-1) steps being controlled radical polymerizations carried out by contacting one or more ethylenically monomer (s). unsaturated (s) different from those of the previous step, at least one source of free radicals and the living polymer composition from the previous step. Thus, the living organic polymers (A) used in the process of the invention may advantageously be polymers resulting from a copolymerization process chosen, for example, from the processes described in patent applications WO 98/01478 and WO 99/35178. , which use reversible transfer agents of the dithioester or dithiocarbamate type, or from the methods of patent applications WO 98/58974, WO 00/75207 and WO 01/042312 implementing reversible transfer agents of xanthate type. It may also be derived polymers obtained according to one of the methods described in patent applications WO 99/35177 or WO 99/31144, which use reversible transfer agents of the dithiocarbamate type, or else according to the process described in US Pat. patent application FR 2794464, which uses thioether-thione reversible transfer agents.

According to a particular embodiment of the invention, the living organic polymers (A) used in the process of the invention may also be derived from the process using the reversible transfer agents of the dithiophosphoroester type of the type which has been used. described in the French patent application No. 00/09952 filed July 28, 2000 by the Applicant, that is to say according to a method comprises at least one step of radical polymerization of a composition containing: - at least one ethylenically unsaturated monomer

- a source of free radicals, and

at least one dithiophosphoroester compound of general formula (F):

SIIR₂- P- S- Ri

I

.R_{3 (}F)

in which :

- R- represents:

•. an alkyl, acyl, aryl, aralkyl, alkene or alkyne group, preferably an alkyl group, advantageously substituted

•. a carbon ring or a heterocycle, saturated or unsaturated, aromatic and optionally substituted,

•. a polymer chain, for example resulting from a radical or ionic polymerization or from a polycondensation,

- R₂ and R₃, identical or different, represent: •. a hydrogen atom, •. -SR₄ , where R₄ has any of the meanings given above <img file="WO02090397A1_D0001.tif" />

•. an optionally substituted alkyl, acyl, aryl, aralkyl or alkyne radical; a carbon ring or heterocycle, saturated or unsaturated, aromatic, optionally substituted; or R₂ and R₃ together represent the atoms necessary to form a carbon ring or heterocycle, saturated or unsaturated, aromatic, optionally substituted; and p is from 2 to 10, the groups Ri, R₂ and R₃which may be substituted, preferably with optionally substituted phenyl groups, optionally substituted aromatic groups, saturated or unsaturated carbon rings, saturated or unsaturated heterocycles, or alkoxycarbonyl or aryloxycarbonyl (-COOR), carboxy (-COOH) groups, acyloxy (-O2CR), carbamoyl (-CONR2), cyano (-CN), alkylcarbonyl, alkylarylcarbonyl, arylcarbonyl, arylalkylcarbonyl, phthalimido, maleimido, succinimido, amidino, guanidimo, hydroxy (-OH), amino (-NR2), halogen, perfluoroalkyl C_notF₂not₊ι, allyl, epoxy, alkoxy (-OR), S-alkyl, S-aryl, groups having a hydrophilic or ionic nature such as the alkaline salts of carboxylic acids, the alkaline salts of sulfonic acid, the poly chains ( alkylene oxide) (poly (ethylene oxide) or poly (propylene oxide) type), cationic substituents (quaternary ammonium salts), R representing an alkyl or aryl group, or a polymer chain.

The optionally substituted alkyl, acyl, aryl, aralkyl or alkyne groups present in the dithiophosphoroesters of formula (F) generally have from 1 to 20, advantageously from 1 to 12, and more preferably from 1 to 9 carbon atoms. They can be linear or branched. They can also be substituted by oxygen atoms, in particular esters, sulfur or nitrogen atoms. Among the alkyl radicals that may be envisaged, there may be mentioned especially the methyl, ethyl, propyl, butyl, pentyl, isopropyl, tert-butyl, pentyl, hexyl, octyl, decyl or dodecyl radical.

Among the aryl radicals, there may be mentioned the phenyl radical, optionally substituted in particular by a nitro or hydroxyl function.

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

According to this specific embodiment, the dithiophosphoroester of formula (F) can advantageously be a compound in which the group R 1 is chosen from the following groups:

<img file="WO02090397A1_D0002.tif" />

- CH (CH3) (CO2Et)

- CH (CH3) (C₆H₅) - CH (C02Et) 2

- C (CH3) (CO₂And) (O-C6H5)

- C (CH₃) 2 (C6H₅)

- C (CH3) 2CN or

<img file="WO02090397A1_D0003.tif" />

where the symbol "Et" represents an ethyl group and the symbol "Ph" represents a phenyl group. Whatever their exact structure, the dithiophosphoroesters of formula (F) are easily accessible. They can thus be obtained in particular by reaction between P₄S₁₀, K₂CO₃ and a halogenated derivative according to a method described for example by Nizamov et al. in Phosphorous Sulfur and Silicon, vol. 132, 85-100 (1998). Another way of accessing compounds of formula (F) is to react an alkali metal salt of a dithiophosphonic acid with a halogenated derivative. In this regard, reference can be made to Mastryukova et al (Bull Sci USSR, Sci Chem (Engl Transi), Vol 27, 1917 (1978)).

According to another conceivable embodiment, the living organic polymers (A) used in the process of the invention may also be silicone / organic hybrid copolymers obtained by a thermally activated radical polymerization preparation method of the type described in US Pat. French patent application FR 00/09722 filed by the applicant on July 25, 2000, namely hybrid silicone / organic copolymers comprising (r) χ (u) ySiO [4 (_x+ y)] / 2 in which:

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

the x groups (r), which are identical or different, each 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 being preferably methyl, ethyl, propyl, octyl and 3,3,3-trifluoropropyl,

^• a cycloalkyl radical containing between 5 and 8 cyclic 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 5 to 14 carbon atoms and an aryl part containing 6 to 12 carbon atoms, optionally substituted on the aryl part by halogens, alkyls and / or alkoxyls containing 1 to 3 atoms of carbon,

the groups (u), identical or different, each represent a grouping:

<img file="WO02090397A1_D0004.tif" />

or: - z, which may differ from one group (u) to another, represent a carbon, sulfur, oxygen, phosphorus, nitrogen and / or free valence, and preferably an atom sulfur or oxygen; - x '= 1, 2,3 or 4 depending on the valence of z,

each of the groups ri, identical or different, represents:

an optionally substituted alkyl, acyl, aryl, alkene or alkyne group, a carbon ring, saturated or unsaturated, optionally substituted and / or aromatic, and / or a heterocycle, saturated or unsaturated, optionally substituted, these groups and (hetero) rings which may be substituted by: substituted phenyl groups, substituted aromatic groups,

Or groups: alkoxycarbonyl, aryloxycarbonyl (-COOr), carboxy

(-COOH), acyloxy (-02Cr⁵), carbamoyl (-CON (r⁵) 2), cyano (-CN), alkylcarbonyl, alkylarylcarbonyl, arylcarbonyl, arylalkylcarbonyl, phthalimido, maleimido, succinimido, amidino, guanidimo, hydroxy (-

5 5

OH), amino (-N (r)₂), halogen, allyl, epoxy, alkoxy (-Or), S-alkyl,

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

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

a group of formula -C_notF_{(2n + 1)} with n between 1 and 20,

a group of formula:

<img file="WO02090397A1_D0005.tif" />

in which :

r 1, r 2, which may be identical or different, are chosen from: a halogen group, -NO 2, -SO 3 r¹⁰, -NCO, -CN, -Or¹⁰, -Sr¹⁰,

-N (R¹⁰)₂, -COOr¹⁰, -O₂Cr¹⁰, -CON (r¹⁰)₂, -NCO (r¹⁰)₂ and -C_notF₍₂not₊i) with n between 1 and 20, preferably 1 and r¹⁰ representing a hydrogen atom or an alkyl, alkenyl, alkynyl, cycloacenyl, cycloalkynyl, alkaryl, aralkyl, heteroaryl or aryl radical optionally fused to an aromatic heterocycle or not; these radicals possibly being substituted with one or more identical or different groups chosen from halogen atoms, = O, = S, -OH, alkoxy, SH, thioalkoxy, NH 2, mono or di-alkylamino, CN, COOH, ester, amide, C_notF (_{2n +}i₎ and / or optionally interrupted by one or more atoms selected from O, S, N, P;

a heterocyclic group optionally substituted with one or more groups as defined above; or r6 and r⁷ together with the carbon atom to which they are attached form a group C = O, C = S, a hydrocarbon ring or a heterocycle;

- and r ^ and r®, identical or different, represent a group as defined above for r¹⁰; or together form a C2-C4 hydrocarbon chain, optionally interrupted by a heteroatom selected from O, S and N;

- V and V, which may be identical or different, represent: H, an alkyl group or a halogen; X and X ', which may be identical or different, represent H, a halogen or a R group;⁴, GOLD⁴, O₂HORN⁴, NHCOH, OH, NH₂, NHR⁴, N (R⁴)₂, (R⁴) 2N⁺O^", NHCOR⁴, CO₂H, CO₂R⁴, CN, CONH₂, CONHR⁴ or CONR⁴₂, in which R⁴ is selected from alkyl, aryl, aralkyl, alkaryl, alkene or organosilyl groups, optionally perfluorinated and optionally substituted by one or more carboxyl, epoxy, hydroxyl, aikoxy, amino, halogen or sulfonic groups,

- r² and r³, identical or different, represent:

- a hydrogen atom

an optionally substituted alkyl, acyl, aryl, alkene or alkyne group; a carbon cycle, saturated or unsaturated, optionally substituted and / or aromatic; a heterocycle, saturated or not, possibly

Substituted, alkoxycarbonyl, aryloxycarbonyl (-COOR),

Carboxy (-COOH), acyloxy (-O2CR), carbamoyl (-CONR 2). cyano (-

CN), alkylcarbonyl, alkylarylcarbonyl, arylcarbonyl, arylalkylcarbonyl, phthalimido, maleimido, succinimido, amidino,

Guanidimo, hydroxy (-OH), amino (-NR 2). halogen, allyl, epoxy,

Alkyloxy (-OR), S-alkyl, S-aryl, hydrophilic or ionic groups such as alkali metal salts of carboxylic acids, alkali metal salts of sulfonic acid, polyalkylene oxide chains),

The cationic substituents (quaternary ammonium salts), R, which may be identical or different, representing an alkyl or aryl group, and / or a polymer chain, these radicals and (hetero) rings being able to be substituted by: substituted phenyl groups, substituted aromatic groups, or alkoxycarbonyl, aryloxycarbonyl (-COOR), carboxy (-COOH), acyloxy (-O2CR) groups,

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 alkaline salts of carboxylic acids, the alkaline salts of sulfonic acid, the polyalkoxide chains, alkylene (POE, POP), the

Cationic substituents (quaternary ammonium salts), R, identical or different, representing an alkyl or aryl group, and / or a polymer chain, - w, which may differ from one group (u) to another, represents a divalent radical chosen from -O-, -NR-, -NH-, or -S-,

- Sp, which may differ from one group (u) to another, represents an organic divalent 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&gt; 1, and when m&gt; 1 repetitive unit units of index m are identical or different.

These particular polymers, which are advantageously in the form of a hybrid silicone / organic copolymer consisting of a linear silicone skeleton comprising from 1 to 300 (preferably 1 to 200) units (r) χ (u) ySiO [4 (_x+ y)] / 2 and having in total from 1 to 50 u radicals, and preferably from 1 to 10 u radicals, can be obtained by a process which comprises reacting a mixture comprising - a radical polymerization initiator.

at least one ethylenically unsaturated monomer of formula CXX '(= CV - CV')_at = CH₂, and

a precursor silicone compound comprising identical or different units of formula

r_xu'ySiO [4_ (_{x +}y)] / 2 in which

r, x and y have the definitions given above, and

the radicals u ', which are identical or different, are monovalent radicals of formula:

<img file="WO02090397A1_D0006.tif" />

where r¹, x ', z, r², r³, w and Sp have the above definitions, the radicals u 'being and are preferably selected from the following radicals:

<img file="WO02090397A1_D0007.tif" />

<img file="WO02090397A1_D0008.tif" />

<img file="WO02090397A1_D0009.tif" />

where R¹ represents a group meeting the definition of the group r¹ defined above.

The precursor silicone compound used in the process for preparing hybrid copolymers can be obtained by reaction:

(i) a silicone comprising units of formula:

RχU "y SiO [4_ (χ₊y)] / 2 where the monovalent radical U "is according to the following formula:

<img file="WO02090397A1_D0010.tif" />

in which - W and Sp are of identical definitions to those given previously,

L is an electrofugal group, for example: Br^", THIS^", f, OTs^", OMs^", (C₆H₆) - (C = O) -O-, (CH₃) - (C = O) -O-, (CF₃) - (C = O) -O \

(ii) with a compound selected from those of the following general formulas:

cs-, M¹ ιι 2+

CS-, M⁺ / (X)

(R¹) x 'Z _ / (IX)

(RV-

<img file="WO02090397A1_D0011.tif" /> in which :

- M '⁺ represents K⁺, N / A⁺, NR₄⁺, or PR ⁺R being of similar definition to that given for R of formula (I),

- M "²⁺ represents an alkaline earth metal such as Ca²⁺, Ba²⁺ and Sr^{2 ++},

M '"represents Zn, Cd, m is 1 or 2, n is 1, 2, 3 or 4 and preferably m is 1 and n is 2.

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

<img file="WO02090397A1_D0012.tif" /> According to yet another conceivable embodiment, the living organic polymers (A) used in the process of the invention may also be so-called "star-shaped" polymers such as those obtained by a process of the type described in US Pat. the French patent application No. 01 05144 filed on April 13, 2001 by the Applicant, namely a process which comprises a step of radical polymerization of a composition containing:

- a source of free radicals, and

at least one polymer composition resulting from a living radical polymerization process and having at the end of the chain at least one reactivatable dithiocarbonyl or dithiophosphorylated function, and

at least one crosslinking monomer, said crosslinking monomer being chosen from organic compounds known to be reactive by a radical route, and comprising between two and ten ethylenic unsaturations, and preferably 2, this crosslinking monomer being advantageously chosen from acrylic derivatives, methacrylic, acrylamido, methacrylamido, vinyl ester, vinyl ether, diene, styrenic, alpha-methyl styrenic and allylic.

In a particularly preferred manner, the living organic polymers (A) used in the process of the invention are polymers resulting from a polymerization or copolymerization process comprising at least one controlled radical polymerization step using a reversible transfer agent. by addition-fragmentation selected from a xanthate, a dithiocarbamate or a dithioester. Advantageously, these are living polymers resulting from the use of transfer agents of the xanthate type.

By "source of free radicals" within the meaning of the invention is meant, broadly, any compound or mixture of compounds capable of leading to the formation of radical species under suitable conditions of implementation (thermal activation, irradiation ...), this compound or mixture of compounds being used in said conditions. Preferably, the source of free radicals (B) used in the process of the present invention is a compound or a mixture of compounds leading to the formation of free radicals under the effect of a heat treatment. Thus, it may for example be a radical polymerization initiator of the usual type. The source of free radicals (B) used in the process of the invention can thus notably be chosen from

hydrogen peroxides, such as tertiary butyl hydroperoxide, cumene hydroperoxide, t-butyl peroxyacetate, t-butylperoxybenzoate, t-butylperoxyoctoate, t-butylperoxynéodécanoate, t-butylperoxyisobutarate, lauroyl peroxide, t-amylperoxypivalte, t-butylperoxypivalate, dicumyl peroxide, benzoyl peroxide, potassium persulfate, or ammonium persulfate;

azo compounds such as: 2-2'-azobis (isobutyronitrile), 2,2'-azobis (2-butanenitrile), 4,4'-azobis (4-pentanoic acid), 1,1'-azobis (isobutyronitrile), azobis (cyclohexane-carbonitrile), 2- (t-butylazo) -2-cyanopropane, 2,2'-azobis [2-methyl-N- (1,1) -bis (hydroxymethyl) -2-hydroxyethyl] propionamide, 2,2'-azobis (2-methyl-N-hydroxyethyl) -propionamide, 2,2'-azobis (N, N'-dimethyleneisobutyramidine) dichloride, 2,2'-azobis dichloride (2-methyl-N-hydroxyethyl) -propionamide -amidinopropane), 2,2'-azobis (N, N'-dimethyleneisobutyramide), 2,2'-azobis (2-methyl-N- [1,1-bis (hydroxymethyl) -2-hydroxyethyl] propionamide) 2,2'-azobis (2-methyl-N- [1,1-bis (hydroxymethyl) ethyl] propionamide) 2,2'-azobis [2-methyl-N- (2-hydroxyethyl) propionamide] or else 2,2'-azobis (isobutyramide) dihydrate, or

redox systems comprising combinations such as, for example:

mixtures of hydrogen peroxide, of alkyl, peresters, percarbonates and the like and of a compound chosen from an iron salt, a titanium salt, zinc formaldehyde sulphoxylate or sodium formaldehyde sulphoxylate, and sugars reducers;

- persulfates, perborates or perchlorates of alkali metals or ammonium, in combination with an alkali metal bisulfite, such as sodium metabisulphite, and reducing sugars;

alkali metal persulfates in combination with an arylphosphinic acid, such as benzene phosphonic acid and the like, and reducing sugars

Preferably, the source of free radicals (B) of the invention comprises a peroxide, advantageously chosen, where appropriate, from the compounds corresponding to one of the following formulas (I) to (IV):

R'-O-O-R "

(D.

R'-O O- R "

OO

(II)

R'- O- π- OOrr- OR "

⁰ ° (III), and

R'-O-π-O-OR "O (IV),

in which the groups R 'and R ", which may be identical or different, represent optionally substituted linear or branched alkyl, aryl or aralkyl groups, for example as examples of peroxides which are particularly suitable as sources of free radicals (B) in the process of the invention, mention may especially be made of diisobutyryl peroxide, cumyl peroxyneodecanoate, ter-amyl peroxyneodecanoate, di (2-ethylhexyl) peroxydicarbonate, tert-butyl peroxyneodecanoate, dibutyl peroxydicarbonate, dicetyl peroxydicarbonate, dimyristyl peroxydicarbonate, tert-butyl peroxyneoheptanoate, tert-amyl peroxypivalate, didecanoyl peroxide, tert-amyl peroxy-2-ethylhexanoate, tert-butyl peroxyisobutyrate, 1,4-di (tert-butylperoxycarbo) cyclohexane, tert-butyl peroxyacetate, tert-butyl peroxybenzoate, di-tert-amyl peroxide ,tert-butyl cumyl peroxide, bis-tert-butyl peroxide, dicumyl peroxide, dilauroyl peroxide or di (4-tert-butylcyclohexyl) peroxydicarbonate.

Whatever its exact nature, the source of free radicals (B) used according to the process of the invention is used under conditions allowing the production of free radicals, which is generally achieved by thermal activation; by raising the temperature of the reaction medium, generally at a temperature of the order of ambient (about 20 ° C) to 200 ° C, preferably from 40 to 180 ° C, preferably from 80 to 160 ° C.

The source of free radicals used can be introduced at once within the reaction medium, but it can also be introduced gradually, where appropriate in portions or continuously.

The amount of the source of free radicals depends on its efficiency and mode of introduction. Advantageously, the source of free radicals used is introduced in an amount such that the quantity of free radicals which it is likely to release is between 50% and 200% by mole, and preferably between 100% and 150% by mole. relative to the total molar quantity of dithiocarbonyl or dithiophosphorylated functional groups carried by all the living organic polymers present in the medium. Another characteristic of the process of the invention is the specific implementation of an organic compound (C) bearing a labile hydrogen atom.

For the purposes of the invention, the term "labile hydrogen" will mean a hydrogen bonded to the organic compound by a sigma bond of sufficiently low intensity that this bond can lead to homolytic radical rupture.

Without wishing to be bound in any way to a particular theory, it seems possible to be argued that, in the method of the invention, free radicals RL^" from the source of free radicals employed react with the dithiocarbonyl function -S (C = S) -R (or -S (P = S) -R) of the living organic polymer, to form radical species according to the following reaction scheme

(Pol) -S (C = S) -R + RL^" &lt;=&gt; (PoI)^" + RL-S (C = S) -R (where (Pol) denotes the polymer chain, the same reaction scheme could be presented with the function -S (P = S) -).

It is assumed that the organic compound carrying a labile hydrogen atom used according to the invention (denoted Org-H) acts as a hydrogen transfer agent and reacts on the radical of the (Pol) type.^" thus formed according to the reaction report:

(Pol)^" + Org-H → (Pol) H + Org^"

In any event, whatever the exact mechanism used in the process of the invention, there is obtained specifically at the end of this process a substitution of the (or) dithiocarbonyl function (s) or dithiophosphorylated (s) initially present on the living organic polymer implemented by a (or) hydrogen atom (s).

The organic compound (C) carrying a labile hydrogen atom which is used according to the invention is preferably chosen from:

secondary alcohols of formula (HO) CH (R ') (R "), -mercaptans of formula R" SH, -phosphites of formula (O =) PH (-OR^lv)(-GOLD^v), silanes of formula R ^,R^ylR^vlSiH, or acetals of formula R^lxCH (OR^x)(GOLD^xl), where the R groups¹, R¹¹, R¹", R^ιv, R^v, R^vι, R^v", R^vl", R^lx, R^x and R^xι are each independently an alkyl, cycloalkyl, alkoxy, alkene, acyl, aryl, aralkyl, aralkenyl or aralkynyl radical, which radicals may be optionally substituted. Preferably, R¹, R¹¹, R¹", R^ιv, R^v, R^vι, R^v", R^V1", R^ιx, R^x and R^xι are chosen from a C1 to C8 alkyl radical and the phenyl radical.

Advantageously, this organic compound (C) bearing a labile hydrogen atom is chosen from 2-propanol, 2-butanol, 2-octanol, mercaptoethanol, diethyl phosphite, benzaldehyde dimethylacetate and dimethylphenylsilane. More particularly, this organic compound (C) is 2-propanol.

Furthermore, the organic compound (C) carrying a labile hydrogen atom used according to the invention is generally an organic compound capable of acting as a solvent for the living polymer used, which has at the end of the chain least a reactivatable dithiocarbony or dithiophosphorylated function. In this case, the amount of compound (C) used is generally between 1 and 50,000 molar equivalents, and preferably between 2 and 10,000 molar equivalents, relative to the polymer (A).

In the case where this compound is not able to perform this role, it is preferred to conduct the reaction in the presence of a co-solvent, chosen, where appropriate, in particular from water, ethanol and toluene. and tetrahyrofuran (THF). In this case, the amount of compound (C) used is most often between 1 and 200 molar equivalents, and advantageously between 20 and 100 molar equivalents, relative to the polymer (A). In the most general case, the compound (C) is used in a proportion of 1 to 50,000 molar equivalents, and preferably between 2 and 10,000 molar equivalents, relative to the polymer (A).

Moreover, in the process of the invention, the step of contacting the living polymer (A), the source of free radicals (B) and the organic compound carrying the labile hydrogen (C) is generally conducted. at a temperature sufficient to allow effective initiation of the source of free radicals, but it is also most often preferred that this temperature is less than or equal to the boiling temperature of the various reagents used, otherwise it is necessary to achieve the method of the invention under pressure, which certainly does not compromise the efficiency of the process in the general case, but is likely to translate into terms of increased implementation costs.

Thus, in the most general case, at atmospheric pressure, it is preferred that this step be carried out at a temperature of between 0.degree.

200 ° C. Preferably, this implementation temperature is greater than

20 ° C, and is advantageously less than 180 ° C. Thus, this temperature can typically be between 40 ° C and 160 ° C.

The nonlimiting examples described below illustrate the process of the invention.

EXAMPLES

Example 1

- Synthesis of a poly (acrylic acid) finished O-ethyl xanthate:

In a two-necked flask surmounted by a condenser, 7 g of acrylic acid are introduced,

28 g of ethanol, 2.02 g of S-ethylpropionyl O-ethyl xanthate and 0.48 g of azobisisobutyronitrile. The mixture is heated at 70 ° C for 4 hours. The polyacrylic acid obtained has the following characteristics: Mn = 2950 g / mol, Mw / Mn = 1.19.

Mn is the average molar mass in number. It is measured by size exclusion chromatography (CES) in water, with relative calibration by polyethylene oxide.

Mw / Mn is the polymolecularity index (given by CES). Mw is the average molar mass by weight.

- Radical reduction of the acrylic polyacid finished O-ethyl xanthate:

To a sample of 20 ml of solution of the acrylic polyacid of Example 1, 27.8 g of 2-propanol are added. The mixture is then heated to 80 ° C. 0.37 g of dilauroyl peroxide are introduced every two hours for 14 hours. Then the system is kept warm for another 3 hours. At the end of the reaction, the crude reaction product is analyzed by CES in water. By UV detection at 290 nm, wavelength at which the group S (C = S) xanthate absorbs very strongly, it is found a total disappearance of the signal. This is characteristic of the total reduction of the xanthate chain end.

Also, after purification of the sample by liquid-liquid extraction (hexane / ether), the analysis of the proton and carbon-purified NMR purified acrylic acid shows the absence of the characteristic signals of the xanthate end.

Example 2

- Radical reduction of the acrylic polyacid finished O-ethyl xanthate:

To a sample of 20 ml of solution of the acrylic polyacid whose synthesis is described above, 27.8 g of 2-propanol are added. The mixture is then heated to 80 ° C. 3.7 p-di-t-butylcyclohexyl percarbonate are then introduced, and the reaction is conducted at this temperature for five hours. At the end of the reaction, the crude reaction product is analyzed by CES in water. By UV detection at 290 nm, wavelength at which the group S (C = S) xanthate absorbs very strongly, it is found a total disappearance of the signal. This is characteristic of the total reduction of the xanthate chain end. Also, after purification of the sample by liquid-liquid extraction (hexane / ether), the analysis of the purified acrylic acid by proton and carbon NMR shows the