MXPA99011605A - Method for block polymer synthesis by controlled radical polymerisation - Google Patents

Abstract

The invention concerns a method for polymerising block polymers of general formula (I) which consists in contacting:an ethylenically unsaturated monomer of formula:CYY'(=CW-CW')a=CH2;a precursor compound of general formula (II);a radical polymerisation catalyst.

Description

PROCEDURE FOR THE SYNTHESIS OF POLYMERS IN BLOCK BY POLYMERIZATION CONTROLLED BY RADICALS DESCRIPTION OF THE INVENTION The present invention relates to a novel radical polymerization process that provides access to block copolymers. The block polymers are usually prepared by ionic polymerization. This type of The polymerization has the drawback of not allowing polymerization more than of certain types of apolar monomers, particularly styrene and butadiene, and of requiring a particularly pure reaction medium and temperatures many times lower than the environment, 15 to minimize parasitic reactions. , of the strain (s) of severe application (s). Radical polymerization has the advantage of being easily applied without conditions of excessive purity being respected, and at temperatures equal to or greater than ambient. However, until recently, there was no radical polymerization procedure that allowed block polymers to be obtained. Since then, a new radical polymerization procedure has been developed: of the radical polymerization called "controlled" or "live". The controlled radical polymerization proceeds by growth by propagation of macroradicals. These macroradicals, endowed with a very short lifetime, are irreversibly recombined by coupling or dismutation. When the polymerization is carried out in the presence of several comonomers, the variation of the composition of the mixture is infinitely small before the macroradical life time, so that the chains present a chain of statistical monomer units and not a chain in sequence . Recently, controlled radical polymerization techniques have been developed, in which the ends of the polymer chains can be reactivated in the form of a radical by homolytic cleavage of the bond (for example C-0, or C-Halogen) .

The radical controlled polymerization thus presents the following distinctive features: 1. the number of chains is fixed throughout the duration of the reaction, 2. the chains all grow at the same speed, which translates to:, a linear increase of the molecular masses with the conversion, . a narrow distribution of the masses,. the most molecular average is controlled by the monomeric molar ratio / chain precursor, 4. the possibility of preparing copolymers in 5 blocks. The controlled character is so much more marked than the speed of reactivation of the radical chains, and very large compared to the speed of growth of the chains (propagation). There is a case where this does not is always true (ie, the rate of reactivation of the radical chains is greater than or equal to the propagation velocity) and conditions 1 and 2 are not observed, however, it is always possible to prepare block copolymers. 15 Several approaches have been described to control radical polymerization. The most commonly cited is to introduce anti-radicals that combine reversibly with growing macroradicals, such as, for example, nitroxyl radicals (Georges et al., Macromolecules, 26, 2987 (1993)). This technique is characterized by elevated temperatures to render the C-O bond labile. Another procedure called Polymerization by 25 Radicals by Transfer of Atoms uses salts of transition metals associated with organic ligands and an initiator generally consisting of an organic halide; control of the polymerization is made possible by the reversibility of the C-5 Halogen bond (Matyj aszewski K., PCT WO 96/30421). One drawback of this polymerization is that a stoichiometric amount of metal remains per chain. Otsu (Otsu et al., Makromol., C, Rapid Comm., 3, 127-132 (1982), Otsu et al., Ibid, 3, 123-140 l 10 (1982), Otsu et al., Polymer Bull ., 7, 45, (1984), ibid, 11, 135, (1984), Otsu et al., J. Macromol. Sci. Chem., A21, 961 (1984), Otsu et al., Acromic lecium, 19, 2087 (1989)), have shown that certain organic sulfides, particularly dithiocarbamates, | 15 allow under UV irradiation to grow chains in a controlled manner, according to the principle: CH, - + < CH, -CH + -CHr -C-N I Ei The principle rests on the photolysis of the C-S junction that regenerates the macro-radical of carbon, on the one hand, and the dithiocarbamyl radical, on the other hand. The controlled nature of the reaction is due to the reversibility of the C-S bond under UV irradiation. It is thus possible to obtain block copolymers. On the other hand, the equilibrium constant of reaction 1 mentioned above is not very large in relation to the speed of propagation, which has the consequence of generating. relatively large molecular weight distributions. Thus, the dispersion index (Id = Mw / Mn) is between 2 and 5 (Otsu et al., 25, 7/8, 643-650 (1989)). The disulfides of xanthates and thiocarbamates are themselves well known as transfer agents in conventional radical polymerization in thermal mode and in the presence of initiator, but none has allowed until this day control the polymerization, much less produce block copolymers. It has hitherto been known that disulfides (tetra-alkylthiurame disulfide, diisopropylxantate disulfide, mercaptobenzotriazole disulfide) are activated thermally or under UV irradiation, whereas monosulfides (dithiocarbamates, substituted xanthates) are activated only under UV irradiation (Ro et al., Macromol. Symp., 91, 81-92 ^ 10 (1995), Oka ara et al., Bull. Of the Tokyo Inst. Of Techn. , No. 78, 1966). The radical-controlled polymerization using a source of UV irradiation is, however, very difficult to apply, particularly from an industrial point of view, since the penetration of UV photons in the polymerization medium is limited, both I by the phenomena of absorption (most of the ethylenic monomers adsorb in the zone of 210-280 ni), as by the phenomena of diffusion in the media dispersed (suspension, emulsion). On the other hand, it has been shown (Turner et al., Macromolecules, 23, 1856-18569 (1990)) that photopolymerization in the presence of dithiocarbamate generates carbon disulfide and can be accompanied by a loss of polymerization control.

For these reasons, it is sought to develop a technique that allows access to block copolymers by a process without UV irradiation, preferably by thermal initiation. Now, to this day, no controlled radical polymerization system has been able to be demonstrated with dithio compounds in the absence of a source of UV radiation. The radical controlled polymerization presents a. advantage over conventional radical polymerization when it comes to preparing low molecular weight and functionalized chains (reactive telomeres). Such polymers are sought for specific applications such as, for example, coatings and adhesives. Thus, when it is sought to synthesize chains grafted with on average 2 functional comonomers, the fraction of chains with at most one functional site becomes important when the average degree of polymerization is lower than a threshold value (for example 20 or 30). The radical controlled polymerization allows it to reduce, even inhibit, the formation of these oligomers to zero or a functional site that diminish the qualities in the application. An object of the present invention is to propose a new controlled radical polymerization process for the synthesis of block polymers. Another object of the present invention is to propose a new controlled radical polymerization process for the synthesis of block polymers in the absence of a UV light source. Another object is to propose a new controlled radical polymerization process, for the synthesis of block polymers, from any type of monomer. Another object is to propose a controlled radical polymerization process, for the synthesis of block polymers that do not contain harmful metallic impurities for their use. Another object is to propose a controlled radical polymerization process, for the synthesis of block polymers, the polymers are functionalized at the end of the chain. Another object is to propose a controlled radical polymerization process for the synthesis of polymers and block copolymers having a small polydispersity index. Another object is to propose a controlled radical polymerization process for the synthesis of oligomers having a proportion of Constant functions from chain to chain. In this object the invention relates to a polymerization process of block polymers of general formula (I): (CW = CW) A - CH2 - j - j - C - (CV = CV ') B CH, in which are contacted: an ethylenically unsaturated monomer of formula CYY '(= CW-CW) a = CH2; - a precursor compound of general formula (II): - (CV = CV ') S - CH2 (II) - a radical polymerization initiator. The invention also relates to block polymers capable of being obtained by the aforementioned process. Finally, the invention relates to polymers of general formula (II) whose index of polydispersity is at most 2. Other details and advantages of the invention will appear more clearly with the reading of the description and the examples. The invention thus relates in the first place to a polymerization process of block polymers of general formula (I): wherein: - z1 = so P, - Z2 = O, S or P, - R1 and R2, identical or different, represent: - a group (i) alkyl, acyl, aryl, alkene or optionally substituted alkyne, or a cycle (ii) of carbon, saturated or not, optionally substituted or aromatic, or - a heterocycle (iii), saturated or not, optionally substituted, these groups or cycles (i), (ii) and (iii) may be substituted by substituted phenyl groups, substituted aromatic groups or groups: alkoxycarbonyl or aryloxycarbonyl (-COOR), carboxy (-COOH), acyloxy (-02CR), carbamoyl (-C0NR2), cyano (-CN), alkylcarbonyl, alkylarylcarbonyl, arylcarbonyl, arylalkylcarbonyl, phthalimido, maleimido, succinimido, amidino, guanidino, hydroxy (-0H), amino (-NR2), halogen, allyl, epoxy, alkoxy (-0R), S-alkyl, S-aryl, the groups having a hydrophilic or ionic character such as the alkali salts of carboxylic acids, the alkali metal salts of sulfonic acid, the alkylene polyoxide chains (POE, POP), the cationic substituents (quaternary ammonium salts), R represents an alkyl or aryl group, a polymer chain, 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 R3, OR3, OCOR3, NHCOH, OH, N¾, NHR3 , N (R3) 2, (R3) 2N * 0", NHCOR3, C02H, C02R3, CN, C0NH2, CONHR3 or CONR32, in which R3 is selected from the groups alkyl, aryl, aralkyl, alkylaryl, alkene or iliyl, optionally perfluorinated and optionally substituted by one or more carboxyl groups, epoxy, hydroxyl, alkoxy, amino, halogen or sulphonic, - a and b, identical or different, are worth 0 or 1, - myn, identical or different, are greater than or equal to 1, and when one or the other is greater than 1, the groups repetitive units are identical or different, in which process they are brought into contact: an ethylenically unsaturated monomer of formula CYY '(= CW-CW) a = C¾ - a precursor compound of general formula (II): - a radical polymerization initiator. The process thus consists in contacting a radical polymerization initiator, an ethylenically unsaturated monomer and a precursor of general formula (II). The radical polymerization initiator can be selected from among the initiators conventionally used in radical polymerization, it can be, for example, one of the following initiators: hydrogen peroxides such as tertiary butyl hydroperoxide, eumeno hydroperoxide, tert-butylperoxyacetate, tert-butylperoxybenzoate, tert-butylperoxyoctoate, tert-butylperoxyneodecanoate, tert-butyl peroxyisobutyrate, lauroyl peroxide, ter-amylperoxypivalate, tert-butylperoxypivalate, dicumyl peroxide, benzoyl peroxide, potassium persulfate, ammonium persulfate. azo compounds such as: 2,2'-azobis (isobutyronitrile), 2,2'-azobis (2-butane-nitrile), 4, '- (4-pentanoic acid), 1,1'-azobis (cyclohexanecarbonitrile), 2- (t-butylazo) -2-cyanopropane, 2, 2'-azobi s [2-methi 1 -N- (1, 1) -b is - (hydroxymethyl) -2-hydroxyethylpropionamide, 2,2'-azobis (2-methyl-N-hydroxyethyl) propionamide, 2,2'-azobis dichloride (?, ? '-dimeti 1 enisobutiramidina), the 2, 2' -azobi s (2-amidinopropane) dichloride, the 2,2'-azobis (N, N '-dimethylene isobutyl amide), the 2, 2' -azobis (2) -methyl-N- [1, l-bis (hydroxymethyl) -2-hydroxyethyl] propionamide, 2,2'-azobi s (2-methy1-N- [1, 1-bis (hydroxymethyl) 1) - ethyl] propionamide, 2,2'-azobis [2-methyl-N- (2-hydroxy-ethyl) ropionamide], 2,2'-azobis (isobutyramide) dihydrate, - the redox systems comprising combinations such as: - the mixtures of hydrogen peroxide, alkyl, peresters, percarbonates and the like and of no matter which of the iron salts, titanium salts, zinc formaldehyde sulfoxylate or sodium formaldehyde sulfoxylate, and reducing sugars, persulphates, perborates or perchlorates of alkali metals or of ammonium, in association with an alkali metal bisulfite, such as sodium metabisulfite, and reducing sugars, - alkali metal persulfates in association with an aryl phosphonic acid, such as benzene sulphonic acid and the like, and reducing sugars. The amount of initiator to be used is determined so that the amount of radicals generated is at most 20 mole% in relation to the amount of compound (II), preferably at most 5 mole%. As the ethylenically unsaturated monomer, monomers selected from styrene or its derivatives, butadiene, chloroprene, (meth) acrylic esters, vinyl esters and vinyl nitriles are more specifically used according to the invention.

Butadiene and chloroprene correspond to the case where a and b = 1 in the formulas (I), (II) and in) the formula of the monomer given above. By (meth) acrylic esters, the esters of acrylic acid and methacrylic acid are referred to as hydrocarbon or fluorinated alcohols having 1 to 12 carbon atoms, preferably 1 to 8 carbon atoms. Among the compounds of this type, mention may be made of: methyl acrylate, ethyl acrylate, propyl acrylate, n-butyl acrylate, isobutyl acrylate, 2-ethylhexyl acrylate, acrylate t-butyl, methyl methacrylate, ethyl methacrylate, n-butyl methacrylate, isobutyl methacrylate. The vinyl nitriles more particularly include those having from 3 to 12 carbon atoms, such as, in particular, acrylonitrile and methacrylonitrile. Let's mention that styrene can be replaced in whole or in part by derivatives such as alphamethylstyrene or vinyltoluene. the other ethylenically unsaturated monomers, usable alone or in mixtures, or copolymerizable with the monomers mentioned above are particularly: vinyl esters of a carboxylic acid such as vinyl acetate, vinyl versatate, vinyl propionate, - vinyl halides, - mono- and di-carboxylic unsaturated ethylenic acids, such as acrylic acid, methacrylic acid, the itaconic acid, the maleic acid, the fumaric acid and the mono-alkyl esters of the dicarboxylic acids of the type mentioned with the albandes having preferably 1 to 4 carbon atoms and their N-substituted derivatives. - amides of unsaturated carboxylic acids such as acrylamide, methacrylamide, N-methylolacrylamide or methacrylamide, N-alkyl acrylamides. - ethylenic monomers comprising a sulphonic acid group and its alkali or ammonium salts, for example vini sulphonic acid, vinylbenzenesulfonic acid, alpha-acrylamido methylpropan sulfonic acid, methacrylate 2-sulfoeti 1 ene, - amides of vinylamine, particularly vinyl formamide or vinyl acetamide, unsaturated ethylenic monomers comprising a secondary, tertiary or quaternary amino group, or a heterocyclic group containing sulfur, such as, for example, vinylpyridines, vinylimidazole, aminoalkyl (meth) acrylates and aminoalkyl (meth) acrylamides such as dimethylaminoethyl acrylate or methacrylate, diter-butylaminoethyl acrylate or methacrylate, acrylamide or methacrylamide dimethylaminomethyl. It is also possible to use zwitterionic monomers such as, for example, sulfopropyl (dimethyl) -aminopropyl acrylate. For the preparation of the copolymers of formula (I) for which Y = H and Y '= NH2, the amides of vinylamine, for example vinylformamide or vinylacetamide, are preferably used as ethylenically unsaturated monomers. Then the obtained copolymer is hydrolyzed at acidic or basic pH.

For the preparation of the copolymers of formula (I) for which Y = H and Y '= OH, the vinyl acetate esters, such as vinyl acetate, are preferably used as ethylenically unsaturated monomers. Then the copolymer obtained is idolyzed at acidic or basic pH. The types and amounts of copolymerizable monomers applied according to the invention vary depending on the particular final application to which the block polymer is intended. These variations are well known and can be easily determined by the person skilled in the art. For the polymer of general formula (I) to be a block polymer, the "precursor" compound of general formula (II) must be a polymer. Thus, n is greater than or equal to 1, preferably greater than or equal to 6. The monomer units of this polymer may be identical or different. According to the preferred variant of the invention, in formula (II) of the precursor compounds, Z1 is a sulfur atom and Z2 is an oxygen atom: these compounds are thus functionalized at the end of the chain by alkyl xanthates. Preferably, in formula (III) of the precursor compounds, R 1 represents: - a group of formula C 'lR'2' 3, in which: - R'1, R'2 and R '3 represent groups (i) , (ii) or (iii) such as defined above, or - R '1 = R' 2 = H and R '3 is an aryl, alkene or alkenyl group, - or a -COR' group in which R4 represents a group (i), (ü) or (iii) as defined above. Also, in the formula (II) of the precursor compounds, R2 preferably represents a group of formula: - CH2R'5, in which R5 represents H or a group (i), (ii) or (iii) with the exception of the aryl, alkyne and alkene groups. The most interesting results have been obtained for the compounds of formula (II) when Zl is a sulfur atom and Z2 is an oxygen atom, R2 is the ethyl or phenyl group, and R1 is a group selected from: C02Et H I - C - CH3 I phenyl - C - C02Et I C02Et CH3 I - C - S | phenyl I C02Et The group R 'can also represent a polymer chain obtained from a radical or ionic polymerization, or be obtained from a poly condensation. Particularly preferred compounds (II) are the homopolymers of styrene (Y '= H, Y = CsH5, b = 0), methyl acrylate (Y' = H, Y = COO e, b = 0), acrylate ethyl (Y '= H, Y = COOEt, b = 0), of butyl acrylate (Y' = H, Y = COOBu, b = 0), of tert-butyl acrylate (Y '= H, Y = COOtBu , b = 0), of vinyl acetate (Y '= H, Y = OCOMe, b = 0),' of acrylic acid (Y '= H, Y = COOH, b = 0), and for which: - Z1 = S, Z2 = O, R1 = CHCH3 (C02Et) and R2 = Et, or - Z1 = S, Z2 = O, R1 = CH (C02Et) 2 and R2 = Et. This precursor polymer (II) can be obtained from the radical polymerization of an ethylenically unsaturated monomer of formula CX '(= CV-CV) b = CH2 by contacting the monomer with a radical polymerization initiator and a compound of general formula ( III), (IV) or (V): sw C-Z1 - R1 I "') R2 - Z2 R2 _ (_ z2 - CZ! - R1). (IV) II s R1? _Z1 - C - Z2 - R2) B (V) II sp is between 2? 10 , preferably between 2 and 5. During this synthesis, the radical polymerization initiators and the ethylenically unsaturated monomers are of the type mentioned above: As for the compounds of general formulas (III), (IV) or (V) , the symbols R ", Z2, R1 and Z1 have the same meaning as above. The preferences regarding their symbols are the same as before. Thus, the compounds of general formula (III) preferred are a-. { 0- e t i lxant i 1) ethyl propionate (Z1 = S, Z2 = 0, R1 = CHCH; (C0: Et) and R2 = Et) and the [l- (0- ethylxantyl) malonate (Z1 = S, Z '= 0, R = CH (C02Et) 2, R' = Et). Among the compounds of formula (IV), those for which R2 is the group - are preferred. { CH2) q- or a polyether group - (CHR-CH2-0) q-CHR-CH2-, with q comprised between 2 and 10. Among the compounds of formula (V), those for which R1 is the group -CH2-phenyl-CH2- or the group -CHCH3C02CH2CH2C02CHCH3- are preferred. The compounds of formulas (III), (IV) and (V) are easily accessible. Those for which Z ~ is a sulfur atom and Z2 is an oxygen atom, called alkyl xanthates, can be obtained in particular by reaction between a xanthate salt, such as an alkaline salt of the type: S w C-S -, M + / RZ-O and a halogenated derivative of the type: Hal-R1 with Hal selected from Cl, Br or I. The compounds of formulas (III), (IV) and (V) in which Z1 is equal to S can also be obtained by the process in which they mix and are heated: - a disulfided compound (S) of formula (A) S - and a diazo compound (N) of formula (B): The complete synthesis process of a block polymer of formula (I) according to the invention can thus consist of: (1) synthesizing a polymer by contact of an ethylenically unsaturated monomer of formula CXX '(= CV-CV) = C¾, a initiator of polymerization by radicals and a compound of formula (III), (IV) or (V). (2) using the polymer obtained in step 1 as a precursor of general formula (II) to prepare a polymer diblocked by contact with a new ethylenically unsaturated monomer of formula CYY '(= CW-CW') a = CH2 and an initiator of radical polymerization. This step (2) can be repeated as many times as desired with new monomers, to synthesize new blocks and obtain a multi-block polymer.

As indicated above, for the preparation of the precursors of formula (II) for the. X = H and X '= NH2 (step (1) defined above), the amides of vinylamine, for example vinyl formamide or vinylacetamide, are preferably used as monomers and t i l ically and unsaturated. Then the obtained polymer is hydrolyzed at acidic or basic pH. Likewise, for the preparation of precursors of formula (II) for which X = H and X '= OH, the vinyl esters of carboxylic acid, such as for example vinyl acetate, are preferably used as ethylenically unsaturated monomers. After the obtained polymer is hydrolyzed to '15 Acid or basic pH. Without thereby excluding any other rational scheme, the assumed reaction mechanism of the polymerization is illustrated below, in the case of a precursor compound of formula (II) of the xanthate type. 1. Polymerization initiation: Ration of the chains * 4cH2 2 - CCrt-CH2-CH ° RMCH, -CH | -CH2 L R2- + p 3. Transgene degenerative chain CH, - CH-CH4- R1 CH2 'The degenerative chain transfer reaction makes it possible to reactivate in. macroradical a "dormant" chain that carries the xanthate group at its end. The latter can grow by propagation, and again add to one end of the xanthate chain and fragment. When the exchange rate of the xanthate is at least as large as the rate of prapagation, then the chains will grow according to a controlled process. When the monomer CH2 = CHR1 is completely consumed, a second monomer of a different nature CH: = CHR: 'is introduced into the medium, block copolymers are then obtained general formula (I): 1 ° CH- CH, CH- CH -.- I, I, 3 Jq R 1 R "R- OMe According to this principle, the invention also relates to a process for the preparation of polymers of multiple blocks, in which the application of the process described above is repeated at least once, using: - monomers different from the previous application, - in place of the precursor compound of formula (II) the block polymer obtained from the preceding application. If the application is repeated once, a triblock polymer will be obtained, if it is repeated a second time, a "quadriblock" polymer will be obtained and so on. In this way, at each new application, the product obtained is a polymer block that has a block of supplementary polymer. Thus, for the preparation of polymers of multiple blocks, the process consists of repeating several times the application of the preceding procedure on the block polymer obtained from each preceding application with different monomers. According to this method of preparing the multi-block polymers, when it is desired to obtain homogeneous block polymers and not 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 a stage have been consumed before the polymerization of the next stage begins, before the new monomers are introduced. The compounds of formulas (IV) and (V) are particularly interesting since they allow to grow a polymer chain on at least two active sites). With this type of compounds, it is possible to economize polymerization steps to obtain a n-block copolymer. Thus, if p is 2 in formula (IV) or (V), the first block is obtained by polymerizing a monomer MI in the presence of the compound of formula (IV) or (V). This first block can then grow I 10 at each of its ends by polymerization of a second monomer M2. A triblock copolymer is obtained, this triblock polymer can, itself, grow at each of its ends by polymerization of a third monomer M3. Thus, a copolymer "pentablock" is obtained in only three stages. If p is greater than 2, the process makes it possible to obtain homopolymers or block copolymers whose structure is "multi-armed" or hyper-branched. 20 The polymerization can be carried out in bulk, in solution or in emulsion. Preferably, it is applied in emulsion. Preferably, the method is applied semi-continuously. 25 The temperature may vary between ambient temperature and 150 ° C depending on the nature of the monomer used. In general, in the course of the polymerization, the instantaneous ratio of the polymer relative to the instantaneous amount of monomer and polymer is between 50 and 99% by weight, preferably between 75 and 99%, even more preferably between 90 and 99%. By polymer, it is meant either the compound of formula (I) for the synthesis of block copolymers, either the compound of formula (II) for the synthesis of the precursor polymer. This proportion is maintained, in a known manner, by controlling the temperature, the rate of addition of the reactants and the polymerization initiator. 15 The procedure is applied in the absence of a I source of UV light. The process according to the invention has the advantage of driving block polymers having a small polydispersity index. It also makes it possible to control the molecular mass of the polymers. The invention thus also relates to block polymers capable of being obtained by the preceding process. 25 These polymers have, in general, an index of polydispersity of at most 2, preferably of at most 1.5. These results are particularly obtained for the polymers in blocks of formula (I) functionalized at the end of the chain by the alkyl xanthate group. These polymers correspond to polymers of general formula (I) for which Z1 is a sulfur atom and Z2 is an oxygen atom. Preferred block polymers are those which have at least two blocks of polymers selected from the following combinations: - polystyrene / methyl acrylate, - polystyrene / ethyl polyacrylate, - polystyrene / tert-butyl polyacrylate, - ethyl polyacrylate / vinyl polyacetate, - Butyl polyacrylate / vinyl polyacetate, - ethyl polyacrylate / tert-butyl polyacrylate, - tert-butyl polyacrylate / vinyl polyacetate, - ethyl polyacrylate / butyl polyacrylate, - Butyl polyacrylate / polyvinyl alcohol, - acrylic polyacid / polyvinyl alcohol. According to a preferred mode, the polymers have at least two polymer blocks selected among the preceding associations and are of general formula (I) / in 1 which: - Z1 = S, Z2 = O, R1 = CHCH3. { C02Et) and R2 = Et, or - Zl = S, Z2 = O, R1 = CH (C02Et) 2 and R2 = Et. Finally, the synthesis process of the precursor polymers of general formula (II) also makes it possible to synthesize polymers having a small polydispersity index. These precursor polymers have, in general, a polydispersity index of at most 2, preferably of at most 1.5, in particular when these polymers are functionalized with alkyl xanthate (Z1 is a sulfur atom and Z2 is an oxygen atom). ). Preferably, n is greater than or equal to 6. Particularly preferred compounds (II) are the homopolymers of styrene (Y '= H, Y = eHs, b = 0), of methyl acrylate (Y' = H, Y = COOMe, b = 0), of ethyl acrylate (Y '= H, Y = COOEt, b = 0), of butyl acrylate (Y = H, Y = COOBu, b = 0), of tert-butyl acrylate (Y '= H, Y = COOtBu, b = 0), of vinyl acetate (Y' = H, Y = OCOMe, b = 0), of acrylic acid (Y '= H, Y = COOH, b = 0), _ and for which: - Z1 = S, Z2 = O, R1 = CHCH3 (C02Et) and R2 = Et, or - Z1 = S, Z2 = O, R1 = CH (C02Et) 2 and R2 = Et. The following examples illustrate the invention without however limiting the annotation.

EXAMPLES 1. SYNTHESIS OF FORMULA PRECURSORS (III) (alkyl xanthate) Example 1.1: Synthesis of ethyl a- (O-ethylxantyl) propionate precursor In a round bottom flask, about 1 liter of ethanol and 80 ml were introduced. of ethyl a-bromopropinate. The flask was immersed in an ice bath. The homogenization was done under stirring in a stream of nitrogen. When the temperature of the reaction medium stabilized, 109 g of potassium O-ethylxanthate was added. Agitation and nitrogen flow were maintained for about 4 hours, during which time the medium became whitish due to the formation of Br. When the reaction was finished, about 1 liter of water was added to the reactor. The medium became clear and yellow. The desired product was extracted from the water-alcohol phase with an ether / pentane mixture (1/2) and recovered by evaporation under vacuum. The 13 C NMR spectrum gave the following maxima: 171.21; 70.11; 61.62; 47.01; 16.82; 14.04; 13. 60 Example 1.2: Synthesis of the precursor [1- (0-ethylxantyl) ethyl] benzene In a round bottom flask, about 1 liter of ethanol and 80 ml of (1-bromoethyl) benzene were introduced. The flask was immersed in an ice bath. The homogenization was done under stirring in a stream of nitrogen. When the temperature of the reaction medium stabilized, 104 g of potassium O-ethylxanthate was added. Agitation and nitrogen flow were maintained for about 4 hours, during which time the medium became whitish due to the formation of KBr. When the reaction was finished, about 1 liter of water was added to the reactor. The medium became clear and yellow. The desired product was extracted from the water-alcohol phase with an ether / pentane mixture (1/2) and recovered by evaporation under vacuum. The 13 C NMR spectrum gave the following maximums: 213.25; 141.73; 128.57; 127.47; 126.49; 69.69; 49.21; 21.70; 13.71.

Example 1.3: Synthesis of the precursor a, a'-di (0-ethylxantil) -p-xylene In a round bottom flask, about 1 liter of ethanol and 80 ml of a, a'-dichloro-p-xylene were introduced. . The flask was immersed in an ice bath. The homogenization was done under stirring in a stream of nitrogen. When the temperature of the reaction medium stabilized, 184 g of potassium 0-ethylxanthate was added. Agitation and nitrogen flow were maintained for about 4 hours, during which time the medium became whitish due to the formation of KB. When the reaction was finished, about 1 liter of water was added to the reactor. The medium became clear and yellow. The desired product was extracted from the water-alcohol phase with an ether / pentane mixture (1/2) and recovered by evaporation under vacuum. The 13 C NMR spectrum gave the following maximums: 135.27; 129.42; 70.23; 40.12; 13.89.

Example 1.4: Synthesis of the precursor α- (O-ethylxantyl) α-phthalimido acetophenone In a round-bottomed flask, 74 ml of acetone and 12.7 g of α-bromo-α-phthalimido acetophenone were introduced. The mixture was homogenized with stirring and a stream of nitrogen. 6.5 g of the potassium O-ethylxanthate salt was added. The reaction lasted for 5 minutes, and then the reaction medium was diluted with distilled water. The precipitated solid was filtered, dried and purified by recrystallization from ethanol. The 13 C NMR spectrum gave the following maximums: 210.0; 189.2; 166.2; 134.4; 133.8; 133.6; 131.5; 128.7; 128.4; 123.7; 71.6; 61.8; 13.6.

Example 1.5: Synthesis of the ethyl a- (O-ethylxantyl) -a-phenylthiopropionate precursor In a round bottom flask, 11 ml of acetone and 2.36 g of the potassium O-ethylxanthate salt were introduced. The mixture was homogenized under stirring and a stream of nitrogen and then, a solution of ethyl a-chloro-a-phenyl-1-thiopropionate (1.56 g) in acetone (4 ml) was added dropwise. The mixture was stirred for 30 minutes. The solvent was evaporated. The residue was diluted with ether, and then washed with water. The organic phase was separated and dried over sodium sulfate. The product was recovered after concentration under vacuum, and purification by chromatography on silica. The 13C NMR spectrum gave the maximum following: 211.3; 168.8; 137.6; 130.4; 129.0; 128.9; 69.72; 62.99; 62.13; 25.56; 13.80; 13.37.

Example 1.6: Synthesis of the precursor O-ethylxantilmalonate In a round-bottomed flask, 50 ml of acetone and 4 ml of diethyl chloromalonate were introduced. The mixture was homogenized under stirring and a stream of nitrogen and 4.4 g of the potassium O-ethylxanthate salt was added. The reaction lasts 1 hour, at the end of which the reaction medium is diluted with 20 ml of water.

The product was extracted from the phase thus obtained with 50 ml of ether, and then purified by flash chromatography. The 13 C NMR spectrum gave the following maximums: 210.3; 165.2; 71.0; 62.8; 56.4; 14.0; 13.6.

Example 1.7: Synthesis of ethyl a- (O-phenylethylxanthyl) -a-phenylthiopropionate precursor In a round bottom flask, were introduced ml of acetone and 5.58 g of the potassium O-ethylxanthate salt. The mixture was homogenized under stirring and a stream of nitrogen and then, the temperature was lowered to 0 ° C. A solution of water was added dropwise to the flask. ethyl a-chloro-a-phenylthiopropionate (6.15 g) in acetone (20 ml). The mixture was stirred for 2 hours. The solvent was then evaporated. The residue was diluted with ether, washed a first time with water, then with a saturated aqueous solution of NaCl. The organic phase was separated and dried over sodium sulfate. The product was recovered in the form of white crystals, after evaporation and Recrystallization from ether at room temperature. The 13 C NMR spectrum gave the following maximums: 211.27; 168.82; 130.42; 69.72; 62.13; 25.56; 13.80; 13.37.

Example 1.8: Synthesis of the ethyl a- (O-) phenylethylxanthyl) -a-phenylethanoate precursor A 1-equivalent phenylethyl alcohol (16.78 ml) in solution in 150 ml of THF was added to a round bottom flask, and then added 1 20 equivalent of NaH (5.68 g) at 0o C. After 2 hours of stirring, 1 equivalent of CS2 (8.48 ml) was added. After stirring overnight at room temperature, the solution was filtered. The salt was washed with pentane and then dried. It was isolated from a quantitatively in the form of a yellow powder, of which 1.09 g were dissolved in 5 ml of acetone. The solution was cooled to 0 ° C. 1 equivalent (0.99 g) of ethyl a-chlorophenylethanoate was added. The solution was stirred for three hours at room temperature. It was then extracted with ether, dried over magnesium sulfate and concentrated under vacuum. 1.62 g of ethyl α- (O-phenylethylxanthyl) -a-phenylethanoate was recovered. The overall yield of the reaction was 90%.

Example 1.9: Synthesis of the precursor (O-ethylxanthyl) -isobutyroniyl 10 ml of bis (O-ethyl) xanthate were dissolved (2.42 g) in 36 ml of hexane in a 100 ml round bottom flask fitted with a refrigerant and under an inert argon atmosphere. The solution was heated for 15 minutes, and then 1 equivalent of azo-bis-isobutyronitrile (AIBN) (1.64 g) was added. 0.5 equivalents of AIBN (0.82 g) were added after two and a half hours. The solution was dried under vacuum. The product was purified by chromatography and isolated. The performance It was 77%.

Example 1.10: Synthesis of the precursor O-neopentylxanti Ethyl Imalonate A 1-equivalent neopentyl alcohol (2.15 ml) in solution in 30 ml of THF was introduced into a round-bottomed flask. Then 1 equivalent of NaH (0.81 g) was added at 0 ° C. After two hours of stirring, 1 equivalent of CS2 (1.21 ml) was added. After stirring overnight at room temperature, the solution was filtered. The salt was washed with pentane and then dried. It was isolated in a quantitative manner in the form of a yellow powder, of which 1.86 g were dissolved in 10 ml of acetone. The solution was cooled to 0 ° C. 1 equivalent of ethyl chloromalonate (1.61 ml) in 5 ml of acetone was added. The solution was stirred for 4 hours at room temperature. It was then hydrolyzed and extracted with ether. It was then dried over magnesium sulfate and concentrated under vacuum. After purification by chromatography, 2.08 g of product were isolated. The yield was 65%.

Example 1.11: Synthesis of the precursor ethyl O-isobornylxanthylmalonate A 15.4 g of isoborneol in solution in 200 ml of THF was introduced into a round-bottomed flask. The solution was treated with 1 equivalent of NaH at 0 ° C and after two hours of stirring, 6 ml of CS2 was added. The solution was stirred overnight at room temperature, and then filtered. The salts were then washed with ether. The filtrate was concentrated. It was dissolved in pentane and filtered. Finally, it was dried to obtain the sodium salt quantitatively. 5.04 g of this salt were dissolved in 40 ml of acetone. The solution was cooled to 0 ° C. 3.08 ml of ethyl chloromalonate was added thereto. The solution was stirred for one hour at 0 ° C. It was then hydrolyzed, extracted with ether, then dried over magnesium sulfate and concentrated in vacuo. After purification by chromatography on silica, 5.92 g of product were obtained. The yield was 80%.

Example 1.12: Synthesis of the precursor (O-isopropylxanthyl) -valeronitrile 0.336 g of azo-bis-valeronitrile and 0.27 g of bis (0-i sopropi 1) antato were dissolved in dioxane. The temperature was brought to 101 ° C. After 12 hours of stirring, the solvent was evaporated and the residue was purified by chromatography on silica. The product was obtained with a yield of 60%.

EXAMPLES 2 - SYNTHESIS OF FORMULA PRECURSORS (ii) (homopolymers) Example 2.1: Styrene Homopolymer In a 10 ml round bottom flask, 1 mmol of ethyl α- (O-ethylxantyl) propionate (0.222 g) was introduced. and 40 mmol of styrene (4.16 g). The temperature was brought to 125 ° C and 0.03 mmole of lauroyl peroxide (12.8 mg) was added. The polymerization lasted 9 hours, in the course of which several initiator additions were made: - 0.02 mmol after two hours, - 0.02 mmol after four hours, - 0.01 mmol after six hours, - 0.01 mmol after eight hours. The polymer was recovered by precipitation in methanol and analyzed by G.P.C. in a THF medium, and in polystyrene equivalents (see Table 9).

Example 2.2: Homopolymer of styrene In a 10 ml round bottom flask, 1 mmol of [1- (O-eti lxant i 1) e ti 1] benzene (0.226 g) and 40 mmol of styrene (4.16 g) were introduced. . The temperature was brought to 90 ° C and 0.02 mmole of lauroyl peroxide (8.52 mg) was added. The polymerization lasted 12 hours, in the course of which several initiator additions were made: - 0.01 mmol after two hours, - 0.01 mmol after four hours, - 0.01 mmol after six hours, - 0.01 mmol after eight hours, - 0.01 mmol after ten hours. The polymer was recovered by precipitation in methanol and analyzed by G.P.C. in a THF medium, and in polystyrene equivalents (see Table 9).

Example 2.3: Homopolymer of styrene In a 10 ml round-bottomed flask, 1 mmol of a, a'-di (O-ethyl-1) -p-xi le (0.346 g) and 40 mmoles of styrene were introduced ( 4.16 g). The temperature was brought to 90 ° C and 0.02 mmoles were added of lauroyl peroxide (8.52 mg). The polymerization lasted 15 hours, in the course of which several initiator additions were made: - 0.01 mmol after two hours, - 0.01 mmol after four hours, - 0.01 mmol after six hours, - 0.01 mmol after eight hours, - 0.01 mmol after twelve hours, - 0.01 mmol after fourteen hours. The polymer was recovered by precipitation in methanol and analyzed by G.P.C. in a THF medium, and in polystyrene equivalents (see Table 9).

Example 2.4: Styrene homopolymer In a 10 ml round bottom flask, 1 mmol of a- (O-ethylxantyl) -a-phthalimido acetophenone (0.385 g) and 40 mmol of styrene (4.16 g) were introduced. The temperature was brought to 90 ° C and 0.02 mmole of lauroyl peroxide (8.52 mg) was added. The polymerization lasted 15 hours, in the course of which several initiator additions were made: - 0.01 mmol after two hours, - 0.01 mmol after four hours, - 0.01 mmol after six hours, - 0.01 mmol after eight hours, - 0.01 mmol after twelve hours, - 0.01 mmol after fourteen hours. The polymer was recovered by precipitation in methanol and analyzed by G.P.C. in a THF medium, and in polystyrene equivalents (see Table 9).

Example 2.5: Styrene homopolymer In a 10 ml round bottom flask, 1 mmol of ethyl α- (O-ethylxantyl) -a-phenylthiopropionate (0.33 g) and 40 mol of styrene (4.16 g) were introduced. The temperature was brought to 90 ° C and 0.02 mmole of lauroyl peroxide (8.52 mg) was added. The polymerization lasted 15 hours, in the course of which several initiator additions were made: - 0.01 mmol after two hours, - 0.01 mmol after four hours, - 0.01 mmol after six hours, - 0.01 mmol after eight hours, - 0.01 mmol after twelve hours, - 0.01 mmol after fourteen hours. The polymer was recovered by precipitation in methanol and analyzed by G.P.C. in a THF medium, and in polystyrene equivalents (see Table 9).

Example 2.6: Methyl acrylate homopolymer In a 10 ml round bottom flask, 1 mmol of ethyl a- (O-ethylxanthyl) ropionate (0.222 g), 40 mmol of methyl acrylate (AMe) (3.44 g) were introduced. ) and 3.5 ml of toluene. The temperature was brought to 100 ° C and 0.035 mmole of lauroyl peroxide (14.9 mg) was added. The polymerization lasted 15 hours, in the course of which several initiator additions were made: - 0.02 mmol after two hours, - 0.02 mmol after six hours, - 0.02 mmol after ten hours. The polymer was recovered by evaporation, under high vacuum, from the solvents and traces of residual monomers, and analyzed by G.P.C. in a THF medium, and in polystyrene equivalents (see Table 9).

Example 2.7: Methyl acrylate homopolymer In a 10 ml round bottom flask, 1 mmole of ethyl α- (O-ethylxantyl) ropionate (0.222 g) and 40 mmole of methyl acrylate (3.44 g) and 3.5 mmole were introduced. my toluene. The temperature was brought to 80 ° C and 0.03 mmole of lauroyl peroxide (12.8 mg) was added.

The polymerization lasted 45 minutes. The polymer was recovered by evaporation, under high vacuum, from the solvents and traces of residual monomers, and analyzed by G.P.C. in a THF medium, and in polystyrene equivalents (see Table 9).

Example 2.8: Methyl acrylate homopolymer In a 10 ml round bottom flask, 1 mmole of ethyl a- (O-ethyl-1-yl) i-propionate (0.222 g) and 80 mmole of methyl acrylate (6.88 g) were introduced. ). The temperature was brought to 80 ° C and 0.02 mmole of lauroyl peroxide (8.52 mg) was added. The polymerization lasted 45 minutes. The polymer was recovered by evaporation, under high vacuum, from the solvents and traces of residual monomers, and analyzed by G.P.C. in a THF medium, and in polystyrene equivalents (see Table 9).

Example 2.9: Homopolymer of methyl acrylate In a 10 ml round bottom flask, 1 mmol of a- (O-ethylxantyl) -a-phthalimido acetophenone (0.385 g) and 40 mmol of methyl acrylate (3.44 g) were introduced. ). The temperature was brought to 80 ° C and they added 0.02 mole of lauroyl peroxide (8.52 mg). The polymerization lasted 45 minutes. The polymer was recovered by evaporation, under high vacuum from traces of residual monomers. It was analyzed by G.P.C. (see Table 9).

Example 2.10: Ethyl acrylate homopolymer In a 10 ml round bottom flask, 1 mmole of ethyl α- (O-ethylxantyl) propionate (0.222 g) and 40 mmole of ethyl acrylate (AEt) (3.44 g) were introduced. ). The temperature was brought to 80 ° C and 0.02 mmole of lauroyl peroxide (8.52 mg) was added. The polymerization lasted 6 hours. The polymer was recovered by evaporation, under high vacuum from traces of residual monomers. It was analyzed by G.P.C. (see Table 9).

Example 2.11: Methyl acrylate homopolymer In a 10 ml round bottom flask, 1 mmole of ethyl α- (O-ethylxantyl) -a-phenylthiopropionate (0.33 g) and 40 mmole of methyl acrylate (3.44 g) were introduced. ). The temperature was brought to 80 ° C and 0.02 mmole of lauroyl peroxide (8.52 mg) was added. The polymerization lasted 6 hours.

The polymer was recovered by evaporation, under high vacuum of traces of residual monomers. HE I analyzed by G.P.C. (see Table 9).

Example 2.12: 2-ethylhexyl acrylate homopolymer In a 10 ml round bottom flask, 1 mmol of O-ethylxantilmalonate (0.28 g) and ^ 40 moles of 2-ethylhexyl acrylate (A2EH) (7.36 g) were introduced. .

The temperature was brought to 80 ° C and 0.02 mmole of lauroyl peroxide (8.52 mg) was added. The polymerization lasted 6 hours. The polymer was recovered by evaporation, under high vacuum from traces of residual monomers. It was analyzed by G.P.C. (see Table 9).

Example 2.13: Vinyl Acetate Homopolymer In a 10 ml round bottom flask, 1 mmol of ethyl a- (0-et i ixanti 1) propionate (0.222 g) and 40 mmole of vinyl acetate (AVM) were introduced. ) (3.44 g). The temperature was brought to 80 ° C and 0.02 mmole of lauroyl peroxide (8.52 mg) was added. The polymerization lasted 8 hours, in the course of which several initiator additions were made: 25 - 0.01 mmol after two hours, - 0.01 mmol after four hours, - 0.01 mmol after six hours. The polymer was recovered by evaporation, under high vacuum from traces of residual monomers and analyzed by G.P.C. in the middle of THF and in polystyrene equivalents. { see Table 9).

Example 2.14: Vinyl Acetate Homopolymer In a 10 ml round bottom flask, 1 mmol of ethyl α- (O-ethylxantyl) propionate (0.222 g) and 40 mmol of vinyl acetate (3.44 g) were introduced. The temperature was brought to 80 ° C and 0.02 mmole of lauroyl peroxide (8.52 mg) was added. The polymerization lasted 4 hours. The polymer was recovered by evaporation, under high vacuum from traces of residual monomers and analyzed by G.P.C. in the middle of THF and in polystyrene equivalents (see Table 9).

Example 2.15: Homopolymer of stxrene In a 10 ml round bottom flask, 1 mmol (3.8 g) of the polymer obtained from Example 2.1, functionalized at the end of the chain with the O-ethylxanthyl group, and 40 mmol of styrene were introduced. (4.16 g). The temperature was brought to 80 ° C and they added 0.02 mmole of lauroyl peroxide (8.52 mg). ) The polymerization lasted 10 hours, in the course of which several initiator additions were made: 5 - 0.01 mmol after two hours, - 0.01 mmol after four hours, - 0.01 mmol after six hours, - 0.01 mmol after eight hours. ^ The polymer was recovered by precipitation in methanol, and analyzed by G.P.C. in the middle of THF and in polystyrene equivalents (see Table 9). This polymer is a styrene homopolymer, but has been obtained as a diblock copolymer with two polystyrene blocks. Example 2.16: Styrene homopolymer: In a 2 1 reactor, were introduced: - 0.4 g of sodium bicarbonate, - 5.4 g of sodium lauryl sulfate, and 20 - 1020 g of water. The temperature was increased to 85 ° C. An aqueous solution of ammonium persulfate (1.6 g of water + 0.8 g of ammonium persulfate) was added. A continuous addition of a mixture containing 400 25 g of styrene and 2.22 g of a- (O- eti lxant i 1) propionate from ethyl was carried out for 2 hours. The temperature was maintained at 85 ° C for an additional 1 hour, in the course of which an aqueous solution of ammonium persulfate (0.8 g of water + 0.4 g of ammonium persulfate) was introduced. The obtained polymer was recovered after coagulation of the emulsion, and was analyzed by G.P.C. in a medium of THF and in polystyrene equivalents (see Table 9).

Example 2.17: Styrene homopolymer In a 10 ml round bottom flask, 1 mmol of O-ethylxantilmalonate (0.28 g), and 40 mmol of styrene (4.16 g) were introduced. The temperature was brought to 95 ° C and 0.03 mmole of lauroyl peroxide (12.8 mg) was added. The polymerization lasted 10 hours, in the course of which several initiator additions were made: - 0.02 mmoles after two hours, - 0.02 mmoles after four hours, - 0.02 mmoles after six hours, - 0.02 mmoles after eight hours. The polymer was recovered by precipitation in methanol. It was analyzed by G.P.C. in the middle of THF and in polystyrene equivalents (see Table 9).

Example 2.18: Methyl acrylate homopolymer In a 10 ml round bottom flask containing 4 ml of toluene, 1 mmole of 0-ethylxantilmalonate (0.28 g), and 40 mmole of methyl acrylate (3.44 g) were introduced. The temperature was brought to 80 ° C and 0.0.3 mmole of lauroyl peroxide (12.8 mg) was added. The polymerization lasted 26 hours, in the course of which 0.02 mmole of lauroyl peroxide were added every two hours. The polymer was recovered by evaporation under high vacuum of toluene and traces of the residual monomer. It was analyzed by G.P.C. in the middle of THF and in polystyrene equivalents (see Table 9).

Example 2.19: Styrene homopolymer In a 10 ml round bottom flask, 1 mmol of ethyl α- (O-phenylethyl) -a-phenylthiopropionate (0.406 g) and 40 mmol of styrene (4.16 g) were introduced. The temperature was brought to 95 ° C and 0.03 mmole of lauroyl peroxide (12.8 mg) was added.

The polymerization lasted 16 hours, in the course of which 0.02 mmoles of lauroyl peroxide were added every two hours. The polymer was recovered by precipitation in methanol. It was analyzed by G.P.C. in the middle of THF and in polystyrene equivalents (see Table 9).

Example 2.20: Methyl acrylate homopolymer In a 10 ml round bottom flask, 1 mmole of ethyl α- (O-pheni let i lxanti 1) -c-phenylethanoate (0.36 g), and 40 mmole of Methyl acrylate (3.44 g). The temperature was brought to 80 ° C and 0.03 mmole of lauroyl peroxide (12.8 mg) was added. The polymerization lasted 11 hours, in the course of which 0.02 mmole of lauroyl peroxide was added every two hours. The polymer was recovered by evaporation under high vacuum of the toluene and traces of the residual monomer. It was analyzed by G.P.C. in the middle of THF and in polystyrene equivalents (see Table 9).

Example 2.21: Methyl acrylate homopolymer In a 10 ml round bottom flask, 1 mmol of (O-ethylxantyl) isobutyronitrile (0.189 g) and 40 mmol of methyl acrylate (3.44 g) were introduced. The temperature was brought to 80 ° C and .0.03 mmole of lauroyl peroxide (12.8 mg) was added. The polymerization lasted for 6 hours, in the course of which 0.02 mmole of lauroyl peroxide were added every two hours after 2 and 4 hours. The polymer was recovered by evaporation under high vacuum from traces of the residual monomer. It was analyzed by G.P.C. in the middle of THF and in polystyrene equivalents (see Table 9).

Example 2.22: Methyl acrylate homopolymer In a 10 ml round bottom flask, 1 mmole of ethyl O-neopentylxantilmalonate (0.322 g) and 40 mmole of methyl acrylate (3.44 g) were introduced. The temperature was brought to 80 ° C and 0.03 mmole of lauroyl peroxide (12.8 mg) was added. The polymerization lasted 4 hours, in the course of which 0.02 mmole of lauroyl peroxide were added after two hours. The polymer was recovered by evaporation under high vacuum from traces of the residual monomer.

| It was analyzed by G.P.C. in the middle of THF and in polystyrene equivalents (see Table 9). Example 2.23: Methyl acrylate homopolymer Into a 10 ml round bottom flask containing 4 ml of toluene, 1 mmole of ethyl 0-isobornylxanthylmalonate (0.388 g) and 40 mmole of methyl acrylate (3.44 g) were introduced. The temperature was brought to 80 ° C and 0.03 mmole of ^ 10 lauroyl peroxide (12.8 mg) was added. The polymerization lasted 2 hours 30 minutes, in the course of which 0.02 mmole of lauroyl peroxide were added after 2 hours. The polymer was recovered by evaporation under high vacuum of traces of the residual monomer. It was analyzed by G.P.C. in the middle of THF and in I equivalents of polystyrene (see Table 9).

Example 2.24: Vinyl Acetate Homopolymer Into a 10 ml round bottom flask, 1 mmol of ethyl O-isobornymalonate (0.388 g) and 77 mmole of vinyl acetate (6.62 g) were introduced. The temperature was brought to 70 ° C and 0.01 mmol of AIBN (azo-bis-isobutyronitrile) (1.64 mg) was added. The polymerization lasted 24 hours, in the course of which Several additions of AIBN were made: - 1.4 mg after two hours, - 2.2 mg after four hours. The polymer was recovered by evaporation under high vacuum from traces of the residual monomer. It was analyzed by G.P.C. in the middle of THF and in polystyrene equivalents (see Table 9).

Example 2.25: Homopolymer of acrylic acid 25 g of acrylic acid were dissolved in 85 g of water, and then the solution thus obtained was neutralized to a pH of between 6 and 7: this solution is solution 1. 0.35 g of dihydrochloride were dissolved. 2,2'-azobis (2-methylpropionamide) in 150 g of water: this solution is solution 2. In three round bottom flasks each containing a different amount of (O-isopropylxanthyl) -valeronitrile were introduced 11 g of solution 1 and 1.5 g of solution 2. The compositions of the different flasks are summarized in Table A. The temperature was brought to 70 ° C and the polymerization was conducted for 24 hours. The polymer was recovered by evaporation under high vacuum of the water and traces of the monomer residual. It was analyzed by G.P.C. in aqueous medium and in SOP equivalents, the results are shown in Table 1.

Table 1 Example 2.26: Homopolymer Acrylic Acid In a 10 ml round bottom flask containing 4 ml of toluene, 1 mmole of ethyl α- (O-et i lxant i 1) ropionate (0.222 g) and 40 mmoles were introduced. Acrylic acid (2.88 g). The temperature was brought to 80 ° C and 0.04 mmole of lauroyl peroxide (17 mg) was added. The polymerization lasted 6 hours, in the course of which several additions of lauroyl peroxide were made: - 0.04 mmol after two hours, - 0.04 mmol after four hours. The polymer was recovered by low evaporation high empty traces of residual monomer. It was analyzed by G.P.C. in aqueous medium I equivalents of POE (see Table 9).

Example 2.27: Homopolymers of Acrylic Acid Several omopolymers of acrylic acid were prepared as follows: All of the acrylic acid (AA), the AIBN and the precursor of ethyl α- (O-ethylxantyl) propionate were mixed and placed in a round bottom flask. The amounts are indicated in Table 2. The temperature was brought to 80 ° C. The polymerization lasted 6 hours. Traces of residual monomer were removed by evaporation. The results, obtained after the analysis by G.P.C. in a medium of THF and in polystyrene equivalents, are summarized in Table 2. twenty Table 2 Example 2.28: Homopolymers of Acrylic Acid Various homopolymers of acrylic acid were prepared in solution in the following manner. In a round bottom flask, all of the acrylic acid (AA), the AIBN and the precursor of ethyl α- (O-et i lxanti 1) propionate were dissolved in the acetone. The respective amounts of each of the ingredients are summarized in Table 3. The temperature was brought to 60 ° C. The polymerization lasted 3 hours. Traces of residual monomer and solvent were removed by evaporation. The results, obtained after analysis by G.P.C. in a medium of THF and in polystyrene equivalents, are summarized in Table 3.

Table 3 Example 2.29: Ethyl acrylate homopolymer In a round bottom flask, the following were introduced: 33.2 mg of a- (0-etixanti 1) ethyl ropionate (1 equivalent) - 5.01 g of ethyl acrylate (160 equivalents), and - 8.2 mg of AIBN. The temperature was brought to 70 ° C. The polymerization lasted 24 hours. The polymer was recovered by evaporation, under high vacuum, from traces of residual monomer. It was analyzed by G.P.C. in a THF medium, and in polystyrene equivalents (see Table 9).

Example 2.30: Vinyl Acetate Homopolymer In three round bottom flasks containing varying amounts of a- (O-ethylxantyl) propionate. ethyl ether, 4.3 g of vinyl acetate and 59.7 mg of lauroyl peroxide were introduced. The temperature was stirred at 70 ° C and the polymerization lasted 6 hours. The amounts of precursor used are summarized in Table 4.

Table 4 Example 2.31: Styrene homopolymer obtained in emulsion A 1.5 liter reactor equipped with a Teflon anchor stirrer was introduced: - 525 g of water - 0.2 g of sodium hydrogencarbonate and - 10 g of sodium lauulfate. The temperature was brought to 70 ° C and 20 g of styrene and the entire precursor of ethyl α- (O-ethylxantyl) propionate were added in one portion. The temperature was then raised to 85 ° C, and 0.4 g of persulfate was added in one portion.

Ammonium in solution in 16.13 g of water. A continuous styrene feed (180 g) was then started for four hours. The temperature was maintained at 85 ° C for 2 additional hours. The results, obtained after analysis by G.P.C. in a medium of THF and in polystyrene equivalents, are summarized in Table 5.

Table 5 Example 2.32: Styrene Homopolymer Obtained in Emulsion A 1.5 liter reactor equipped with a Teflon anchor stirrer was introduced into: - 475 g of water - 0.2 g of sodium hydrogencarbonate and - 10 g of sodium lauryl sulfate. The temperature was brought to 70 ° C and a portion was added in one portion: - 20 g of styrene and - 2 g of a- (O-ethyl Ixant i 1) ethyl propionate.

The temperature was then raised to 85 ° C, and 0.4 g of ammonium persulfate in solution in 16.13 g of water were added in one portion. It was introduced into the reactor continuously and in parallel: - 180 g of styrene for 8 hours, - 0.4 g of ammonium persulfate in 50.4 g of water for 10 hours. Samples were taken regularly, and analyzed by G.P.C. in a medium of THF and in polystyrene equivalents. The results obtained are summarized in Table 6.

Table 6 A linear increase of the molecular masses is observed with the conversion, which proves the controlled character of radical polymerization.

Example 2.33: Homopolymer of ethyl acrylate A solution was prepared containing: - 17.64 g of ethyl acrylate / - 0.459 g of a- (O-et i lxant i 1) ethyl ropionate, and - 0.036 g of AIBN. 1 g of this solution was introduced into 7 tubes that were used to establish the kinetics of the polymerization. These tubes were then brought to 70 ° C and the reaction was interrupted at different times. For each tube, the polymer was recovered by evaporation of traces of residual monomer and analyzed by G.P.C. in a THF medium, and in polystyrene equivalents. The results obtained are gathered in the Table 7 Table 7 A linear increase of the molecular masses is observed with the conversion, which proves the controlled character of the radical polymerization.

Example 2.34: Vinyl Acetate Homopolymer A solution was prepared which contained: - 7.35 g of vinyl acetate, - 0.229 g of ethyl a- (O-ethyl-1-ethyl), and - 0.0318 g of AIBN. 1 g of this solution was introduced into 4 tubes that were used to establish the kinetics of the polymerization. These tubes were then brought to 70 ° C and the reaction was interrupted at different times.

For each tube, the polymer was recovered by evaporation of traces of residual monomer and analyzed by G.P.C. in a THF medium, and in polystyrene equivalents. The results obtained are gathered in the Table 8 Table 8 A linear increase of the molecular masses is observed with the conversion, which proves the controlled character of the radical polymerization.

Results of Examples 2.1 to 2.24, 2.26 and 2. 29: The analysis by G.P.C. of the homopolymers obtained in the above allowed to measure their average mass of number (Mn). It also allowed to measure its average mass of weight (Mw) and thus its index of polydispersity (Ip), corresponding to the relation Mw on Mn. Systematically, chromatographies of G.P.C. were performed with double detection refractometry (I) and UV absorption (ÜV). The wavelength of UV detection corresponds to the absorption maximum of the fixed xanthate function at the end of the chain according to the claimed formula. For all the samples analyzed, a perfect superimposition of the chromatograms obtained by one or the other detection was obtained.This result indicated a functionalization of the ends of the chains, and constitutes a supplementary test of the assumed structure of the polymers according to the invention. .

Table 9 Ex emplos onomero Mn ip Conversion rate (%) Ex. 2.1 styrene 3,800 2 Ex. 2.2 Styrene 5, 200 2.1 Ex. 2.3 Styrene, 900 2.5 Ex. 2.4 Styrene 3,200 1.8 Ex. 2.5 Styrene 3, 30Q 1.9 Ex. 2.6 AMe 3, 500 1.8 Ex. 2.7 AMe 3, 750 1.7 Ex. 2.8 AMe 7, 300 1.7 Ex. 2.9 AMe 3,000 1.4 Ex. 2.1Q AEt 3, 700 1.6 Ex. 2.11 A e 3, 500 1.35 Ex. 2.12 A2EH 6,900 1.5 Ex. 2.13 AVM 3,200 1.35 E. 2.14 AVM 2,100 1.18 Ex. 2.15 styrene 6,200 2 Ex. 2.16 styrene 3, 800 1.6 Ex. 2.17 is tireno 4, 300 1.9 78 B. 2.18 AMe 3, 900 1.5 95 Ex. 2.19 styrene 3,400 1.8 77 Ex. 2.20 AMe 3, 100 1.6 60 Ex. 2.21 AMe 3, 600 1.4 75 Ex. 2.22 A e 5,100 1.4 90 Ex. 2.23 AMe 4,000 1.7 88 Ex. 2.24 AVM? 2,500 1.8 29 E. 2.26 AA 6,600 2.3 97 Ex. 2.29 AEt 29, 400 1.9 93 Example 2.35: Homopolymer of vinyl acetate A 0.8 ml of vinyl acetate (or about 10 equivalents) was added to a round bottom flask - 0.220 g of ethyl α- (O-ethylxanti 1) ropionate (1 equiv. alente), and - 17.2 mg of AIBN. The temperature was brought to 70 ° C. The polymerization lasted 24 hours. The polymer was recovered by evaporation, under high vacuum, from traces of residual monomers and analyzed by MALDI-TOF, on a matrix of DHB (dihydroxybenzoic acid). The results are gathered in Table 10.

Table 10 In Table 10, the theoretical mass calculated assuming a conformal structure formula: It is necessary to add 23 g to the mass obtained since the detected species are in the form of a sodium salt. The excellent agreement between the theoretical mass and the measurements with MALDI-TOF are a confirmation of the mechanism assumed for the polymerization and the structure of the polymers obtained.

EXAMPLES 3 - SYNTHESIS OF COPOLYMERS IN BLOCKS Example 3.1: Block copolymer (AMe-b-St) In a 10 ml round-bottomed flask, insert: - 1 mmol of a- (O- eti lxant i 1 ) ethyl ropion (0.222 g), and - 20 Miloles of methyl acrylate (1.72 g). The mixture was brought to 80 ° C, and 0.02 mmole of lauroyl peroxide (8.52 mg) was added. The mixture was kept at that temperature for 45 minutes, at the end of which it coagulated. The reaction medium was then dissolved in 3 ml of toluene, and then it was evaporated to dryness. This operation was repeated three times to eliminate traces of residual methyl acrylate. This synthesis led to a useful precursor for the preparation of a block copolymer. 20 mmol of styrene (2.08 g) were then introduced into the reactor. The temperature was brought to 110 ° C and 0.02 mmole of lauroyl peroxide (8.52 mg) was added. This second stage lasted 6 hours, in the course of which several initiator additions were made: - 0.01 mmol after two hours, - 0.01 mmol after four hours. The copolymer obtained was recovered by precipitation in methanol, and analyzed by G.P.C. double detection: refractometry and UV spectrometry. The solvent of the G.P.C. is the THF, and the masses were given in polystyrene equivalents. The results are given in Table 12.

Example 3.2: Copolymer in blocks of (St-b-A e) In a 10 ml round bottom flask were introduced: - 1 mmol of ethyl a- (O-ethyl-1) propionate (0.222 g). - 20 mmoles of styrene (2.08 g), and - 1 ml of toluene. The reaction medium was brought to 110 ° C, and 0.025 mmole of lauroyl peroxide (10.6 mg) was introduced into the reactor. This first stage lasted 9 hours, in the course of which several initiator additions were made: - 0.01 mmol after two hours, - 0.01 mmol after four hours, - 0.01 mmol after six hours, - 0.01 mmol after eight hours hours. The medium was then cooled to 80 ° C, and introduced: - 20 mmoles of methyl acrylate (1.72 g), and - 0.03 mmole of lauroyl peroxide (12.8 mg). This second stage lasted 7 hours, in the course of which several initiator additions were made: - 0.01 mmol after two hours, - 0.01 mmol after four hours, - 0.01 mmol after six hours. The obtained polymer was recovered and analyzed as in Example 3.1. The results are given in Table 11.

Example 3.3: Copolymer in blocks of p (St-b-AMe) In a 10 ml round bottom flask were introduced: - 1 mmol of [1- (O-ethylxantyl) ethyl] benzene (0.226 g), and - 20 mmoles of styrene (2.08 g). The temperature was brought to 90 ° C, and 0.03 mmole of lauroyl peroxide (12.8 mg) was introduced. The temperature was maintained at 90 ° C for 10 hours, in the course of which several initiator additions were made: - 0.01 mmol after two hours, - 0.01 mmol after four hours, - 0.01 mmol after six hours, - 0.01 mmol after eight hours. The reaction medium was then cooled to 80 ° C, and the following were introduced: - 20 mmol of methyl acrylate (1.72 g), and - 0.02 mmol of lauroyl peroxide (8.52 mg). This second stage lasted 8 hours, in the course of which several initiator additions were made: - 0.01 mmol after two hours, - 0.01 mmol after four hours, - 0.01 mmol after six hours, - 0.01 mmol after seven hours.

The obtained polymer was recovered and analyzed as in Example 3.1. The results are given in Table 12.

Example 3.4: Copolymer in blocks of p (St-b-AMe-b-St) Into a 10 ml round bottom flask were introduced: - 1 mmol of [1- (O-ethylxantyl) ethyl] benzene (0.226 g), and - 20 mmol of styrene (2.08 g). The temperature was brought to 90 ° C, and 0.03 mmole of lauroyl peroxide (12.8 mg) was introduced. The temperature was maintained at 90 ° C for 10 hours, in the course of which several initiator additions were made: - 0.01 mmol after two hours, - 0.01 mmol after four hours, - 0.01 mmol after six hours, - 0.01 mmol after eight hours. The reaction medium was then cooled to 80 ° C, and were introduced: - 20 mmoles of methyl acrylate, and - 0.02 mmoles of lauroyl peroxide. This second stage lasted 8 hours, in the course of which several initiator additions were made: - 0.01 mmol after two hours, - 0.01 mmol after four hours, - 0.01 mmol after six hours, - 0.01 mmol after seven hours. The temperature was brought back to 90 ° C, and were added: - 20 mmoles of styrene (2.08 g), and - 0.02 mmoles of lauroyl peroxide. This third stage lasted 8 hours, in the course of which several initiator additions were made: - 1 mmol after two hours, - 1 mmol after four hours, - 1 mmol after six hours. The obtained polymer was recovered and analyzed as in Example 3.1. The results are given in Table 12.

Example 3.5: Copolymer in blocks of p (AMe-b-St) In a round bottom flask were introduced: - 1 mmol of [1 - (O-eti lxanti 1) eti 1] benzene (0.226 g), and - 20 mmol of ethyl acrylate (1.72 g). The temperature was brought to 80 ° C, and 0.02 mmole of lauroyl peroxide was added. This first stage lasted 8 hours, in the course of which they were carried out several additions of initiator: - 1 mmol after two hours, - 1 mmol after four hours, - 1 mmol after six hours. The temperature was brought back to 90 ° C, and were introduced: - 20 mmoles of styrene (2.08 g), and - 0.02 mmoles of lauroyl peroxide. This second stage lasted 14 hours, in the course of which several initiator additions were made: - 0.01 mmol after two hours, - 0.01 mmol after four hours, - 0.01 mmol after six hours, - 0.01 mmol after eight hours hours, - 0.01 mmol after ten hours, - 0.01 mmol after twelve hours. The obtained polymer was recovered and analyzed as in Example 3.1. The results are given in Table 12.

Example 3.6: Block copolymer of p (AEt-b-AVM) They were introduced into a round bottom flask: - 1,881 g of ethyl acrylate, - 0.111 g of ethyl a- (O-et ixxyl) ropionate, and - 8.6 mg of lauroyl peroxide.

The temperature was brought to 80 ° C. The polymerization lasted 6 hours, in the course of which several additions of lauroyl peroxide were made: - 9.2 mg after 2 hours, - 9.0 mg after 4 hours. After cooling, traces of residual ethyl acrylate were removed by evaporation under high vacuum, and a small fraction of the polymer was taken to be analyzed by G.P.C. in a medium of THF, and in equivalents of polyes ti rein. The results are the following: - conversion rate: 98.3, - Mn = 2,800, - Ip = 1.8. Then 1,853 g of vinyl acetate and 8.6 mg of lauroyl peroxide were introduced into the flask. The temperature was brought to 80 ° C. The polymerization lasted 6 hours, in the course of which several additions of lauroyl peroxide were made: - 8.6 mg after 2 hours, - 8.5 mg after 4 hours. Traces of residual vinyl acetate were removed by evaporation under high vacuum. The results are given in Table 12.

Example 3.7: Block copolymer of p (AEt-b-AtBu) They were introduced into a round bottom flask: 1,881 g of ethyl acrylate, 0.111 g of ethyl a- (O-ethylxantyl) ropionate, and - 9.0 mg of lauroyl peroxide. The temperature was brought to 80 ° C. The polymerization lasted 6 hours, in the course of which several additions of lauroyl peroxide were made: - 8.6 mg after 2 hours, - 8.9 mg after 4 hours. After cooling, traces of residual ethyl acrylate were removed by evaporation under high vacuum, and a small fraction of the polymer was taken to be analyzed by G.P.C. in a medium of THF, and in polystyrene equivalents: - conversion rate: 98.6%, - 'Mu. = 2, 600, - Ip = 1.9. The flask was then introduced: - 2.7467 g of tert-butyl acrylate, and - 8.5 mg of lauroyl peroxide. The temperature was brought to 80 ° C. The polymerization lasted 6 hours, in the course of which several additions of lauroyl peroxide were made: - 8.7 mg after 2 hours. - 8.5 mg after 4 hours. Traces of residual tert-butyl acrylate were removed by evaporation under high vacuum, and the copolymer obtained was analyzed by G.P.C. in the middle of THF and in polystyrene equivalents. The results are given in Table 12.

Example 3.8: Copolymer in blocks of p (AtBu-b-AVM) A round bottom flask was introduced: - 2737 g of tert-butyl acrylate, - 0.111 g of a- (O-eti Ixant i 1) pro ionato of ethyl, and - 8.7 mg of lauroyl peroxide. The temperature was brought to 80 ° C. The polymerization lasted 6 hours, in the course of which several additions of lauroyl peroxide were made: - 8.9 mg after 2 hours, - 8.9 mg after 4 hours. After cooling, traces of residual tert-butyl acrylate were removed by evaporation under high vacuum, and a small fraction of the polymer was taken to be analyzed by G.P.C. in a medium of THF, and in polystyrene equivalents: - conversion rate: 98.3%, - Mn = 2,500, - Ip = 2.4.

The flask was then introduced: - 1851 g of vinyl acetate, and - 8.5 mg of lauroyl peroxide. The temperature was brought to 80 ° C. The polymerization lasted 6 hours, in the course of which several additions of lauroyl peroxide were made: - 8.7 mg after 2 hours, - 8.5 mg after 4 hours. Traces of residual vinyl acetate were removed by evaporation under high vacuum, and the copolymer obtained was analyzed by G.P.C. in the middle of THF and in polystyrene equivalents. The results are given in Table 12.

Example 3.9: Copolymer in blocks of p. { AtBu-b-AEt) were introduced into a round bottom flask: - 2737 g of tert-butyl acrylate, - 0.111 g of a-. { Ethyl o-ethylxanthyl) ropionate, and - 8.4 mg of lauroyl peroxide. The temperature was brought to 80 ° C. The polymerization lasted 6 hours, in the course of which several additions of lauroyl peroxide were made: - 9.0 mg after 2 hours, - 8.7 mg after 4 hours. After cooling, the traces of residual tert-butyl acrylate by evaporation under high vacuum, and a small fraction of the polymer was taken to be analyzed by G.P.C. in a THF medium, and in polystyrene equivalents: - conversion rate: 98.1%, - Mn = 2,500, - Ip = 2.5. The flask was then introduced: - 1,896 g of ethyl acrylate, and - 8.8 mg of lauroyl peroxide. The temperature was brought to 80 ° C. The polymerization lasted 6 hours, in the course of which several additions of lauroyl peroxide were made: - 8.7 mg after 2 hours, - 8.5 mg after 4 hours. Traces of residual ethyl acrylate were removed by evaporation under high vacuum, and the obtained copolymer was analyzed by G.P.C. in the middle of THF and in "polystyrene equivalents." The results are given in Table 12.

Example 3.10: Block copolymer of p (AEt-b-St) They were introduced into a round bottom flask: 1,881 g of ethyl acrylate, 0.111 g of ethyl a- (O-ethylxantyl) ropionate, and - 8.8 mg lauroyl peroxide. The temperature was brought to 80 ° C. The polymerization lasted 6 hours, in the course of which several additions of lauroyl peroxide were made: 5 - 9.0 mg after 2 hours, - 8.5 mg after 4 hours. After cooling, traces of residual ethyl acrylate were removed by evaporation under high vacuum, and a small fraction of the polymer was taken to be analyzed by G.P.C. in a medium of THF, and in polystyrene equivalents: - conversion rate: 97.5%, - Mn = 3,000, - Ip = 1.8. The following were then introduced into the flask: - 2,231 g of styrene, and - 9.0 mg of lauroyl peroxide. The temperature was brought to 115 ° C. The polymerization lasted 6 hours, in the course of which, 20 several additions of lauroyl peroxide were made: - 8.7 mg after 2 hours, - 9.9 mg after 4 hours. Traces of residual styrene were removed by evaporation under high vacuum, and the obtained copolymer 25 was analyzed by G.P.C. in the middle of THF and in polystyrene equivalents. The results are given in Table 12. I Example 3.11: Block copolymer of p (AtBu-b-St) The following were placed in a round bottom flask: - 2737 g of tert-butyl acrylate, - 0.111 g of ethyl α- (0-ethyl-1-yl) 1-propionate, and - 9.0 mg of lauroyl peroxide. The temperature was brought to 80 ° C. The polymerization lasted 6 hours, in the course of which several additions of lauroyl peroxide were made: - 8.5 mg after 2 hours, - 9.6 mg after 4 hours. After cooling, traces of residual tert-butyl acrylate were removed by evaporation under high vacuum, and a small fraction of the polymer was taken to be analyzed by G.P.C. in a medium of THF, and in polystyrene equivalents: - conversion rate: 98.4%, 20 - Mn = 2, 800, - Ip = 2.4. The flask was then introduced: - 2,246 g of styrene, and - 8.4 mg of lauroyl peroxide. 25 The temperature was brought to 115 ° C. polymerization lasted 6 hours, in the course of which, several additions of lauroyl peroxide were made: - 9.2 mg after 2 hours, - 9.2 mg after 4 hours. Traces of residual styrene were removed by evaporation under high vacuum, and the copolymer obtained was analyzed by G.P.C. in the middle of THF and in polystyrene equivalents. The results are given in Table 12.

Example 3.12: Copolymer in blocks of p (AEt-b-AtBu-b-St) They were placed in a round bottom flask: - 2,248 g of styrene, - the total copolymer obtained in Example 3.7, and - 8.3 mg of lauroyl peroxide. The temperature was brought to 115 ° C. The polymerization lasted 6 hours, in the course of which several additions of lauroyl peroxide were made: - 9.0 mg after 2 hours, - 8.5 mg after 4 hours. Traces of residual styrene were removed by evaporation under high vacuum, and the copolymer obtained was analyzed by G.P.C. in a THF medium, and in polystyrene equivalents. The results are given in Table 12.

Example 3.13: Copolymer in blocks of p (St-b-AEt) were introduced into a round bottom flask: - 2,224 g of styrene, - 0.111 g of ethyl α- (O-ethylxantyl) propionate, and - 8.6 mg of lauroyl peroxide. The temperature was brought to 115 ° C. The polymerization lasted 6 hours, in the course of which several additions of lauroyl peroxide were made: - 8.7 mg after 2 hours, - 8.3 mg after 4 hours. After cooling, traces of residual styrene were removed by evaporation under high vacuum, and a small fraction of the polymer was taken to be analyzed by G.P.C. in a medium of THF, and in polystyrene equivalents: - conversion rate: 98.0%, - Mn = 3,500, - Ip = 2.2. The flask was then introduced: - 2 ml of toluene, - 1892 g of ethyl acrylate, and - 8.5 mg of lauroyl peroxide. The temperature was brought to 80 ° C. polymerization lasted 6 hours, in the course of which, several additions of lauroyl peroxide were made: - 9.4 mg after 2 hours, - 9.2 mg after 4 hours. Traces of residual ethyl acrylate were removed by evaporation under high vacuum, and the copolymer obtained was analyzed by G.P.C. in the middle of THF and in polystyrene equivalents. The results are given in Table 12. ?? Example 3.14: Copolymer in blocks of p (St-b-AtBu) A round bottom flask was introduced: - 2,224 g of styrene, - 0.111 g of ethyl α- (O-ethylxantyl) ropxonate, and 15 - 8.6 mg of lauroyl peroxide. The temperature was brought to 115 ° C.

I polymerization lasted 6 hours, in the course of which several additions of lauroyl peroxide were made: - 8.7 mg after 2 hours, 20 - 9.5 mg after 4 hours. After cooling, traces of residual styrene were removed by evaporation under high vacuum, and a small fraction of the polymer was taken to be analyzed by G.P.C. in a medium of THF, and in 25 equivalents of polystyrene: - conversion rate: 97.2%, - Mn = 3, 00, - Ip = 2.2. The flask was then introduced: - 2 ml of toluene, - 2,747 g of tert-butyl acrylate, and - 9.3 mg of lauroyl peroxide. The temperature was brought to 80 ° C. The polymerization lasted 6 hours, in the course of which several additions of lauroyl peroxide were made: - 8.7 mg after 2 hours, - 9.3 mg after 4 hours. Traces of residual tert-butyl acrylate were removed by evaporation under high vacuum, and the copolymer obtained was analyzed by G.P.C. in the middle of THF and in polystyrene equivalents. The results are given in Table 12.

Example 3.15: Copolymer in blocks of p (AtBu-b-AEt-b-St) They were placed in a round bottom flask: - 2 ml of toluene, - 2229 g of styrene, - the total copolymer obtained in Example 3.9, and - 9.1 mg of lauroyl peroxide.

The temperature was brought to 120 ° C. The polymerization lasted 6 hours, in the course of which several additions of lauroyl peroxide were made: - 8.5 mg after 2 hours, - 8.5 mg after 4 hours. Traces of residual styrene were removed by evaporation under high vacuum, and the copolymer obtained was analyzed by G.P.C. in the middle of THF and in polystyrene equivalents. The results are given in Table 12.

Example 3.16: Block copolymers of pABu-b-APV (APV: polyvinyl alcohol) These copolymers were obtained by hydrolysis of their p equivalents (ABu-b-AVM). A series of block copolymers of p (ABu-b-AVM) was prepared. All copolymers were obtained according to the following general procedure. They were placed in a round bottom flask: - butyl acrylate (ABu), - ethyl α- (O-ethylxantyl) propionate, and - about one third of the overall amount of lauroyl peroxide required for this first stage.

The temperature was brought to 80 ° C. The polymerization lasted 6 hours, in the course of which two initiator additions were made after 2 and 4 hours. Each of the additions corresponds to about one third of the total amount of lauroyl peroxide in the first stage. Traces of residual butyl acrylate were removed by evaporation, and a small fraction of the polymer was taken to be analyzed. The flask was then added: - vinyl acetate, and - about one third of the total amount of lauroyl peroxide required for this second stage.

The temperature was brought back to 80 ° C. The polymerization lasted 6 hours, and the remainder of the initiator was added in the same manner as for the synthesis of the first block. The block copolymer was recovered after evaporation of traces of residual vinyl acetate, and analyzed by G.P.C. in a medium of THF and in polystyrene equivalents. The amounts of the ingredients used for each of the copolymers, as well as the results obtained are summarized in Table 11.

Table 11 The block polymers obtained were then hydrolysed: they were dissolved in methanol, in 50% dry extract, and then a catalytic amount of soda was added, and the reaction medium was brought to 60 ° C for 1 hour. The pABu-b-APV copolymers were recovered by evaporation of the methanol.

Example 3.17: Copolymer in blocks of pAA-b-APV This copolymer was obtained by hydrolysis of the corresponding copolymer of p (AtBu-b-AVM). They were placed in a round bottom flask: - 2,737 g of tert-butyl acrylate, - 0.111 g of ethyl α- (O-ethylxantyl) propionate, and - 8.5 mg of lauroyl peroxide. The temperature was brought to 80 ° C. The polymerization lasted 6 hours, in the course of which several additions of lauroyl peroxide were made: - 9.5 mg after 2 hours, - 9.8 mg after 4 hours. After cooling, traces of residual tert-butyl acrylate were removed by evaporation under high vacuum. A small fraction of the polymer was taken to be analyzed by G.P.C. in a THF medium, and in polystyrene equivalents: - conversion rate: 99.0%, - Mn = 4,300, - Ip = 1.7. The flask was then introduced: - 1,831 g of vinyl acetate, and - 8.6 mg of lauroyl peroxide.

The temperature was brought to 80 ° C. The polymerization lasted for 6 hours, during which several additions of lauroyl peroxide were made: 5 - 9.2 mg after 2 hours, - 9.2 mg after 4 hours. Traces of residual vinyl acetate were removed by evaporation under high vacuum, and the obtained copolymer was analyzed by G.P.C. between THF and in polystyrene equivalents. The results are given in Table 12. The obtained copolymer was then hydrolyzed in the following manner. The copolymer was introduced into a water / methanol mixture (10 ml / 4 ml). Three drops of 95% sulfuric acid were added to obtain a pH of 1. The temperature was brought to 70 ° C. After 2 hr 15 minutes, 8 ml of methanol were added and, after 5 hours, three additional drops of methanol were added. 95% sulfuric acid 20%. This first stage lasted 24 hours, and allowed the transformation of the ter-butyl polyacrylate block into polyacrylic acrylic. The temperature was then restored to the environment, and the solvent (water + methanol) was removed by evaporation. The dry residue obtained is it was redissolved in 30 ml of methanol, and a catalytic amount of NaOH was added. The temperature was brought back to 70 ° C, where it was kept for 24 hours. The obtained polyacrylic acid / polyvinyl alcohol copolymer was recovered by evaporation of methanol.

Example 3.18: Copolymer in blocks of p (ABu-b-AEt) In a reactor equipped with a stirring system were introduced: - 60 g of isopropyl acetate, - 90 g of butyl acrylate, and - 6.9 g of a- Ethyl (O-ethylxantyl) ropionate. The temperature was brought to 80 ° C. 0.18 g of AIBN in solution in 5 g of isopropyl acetate were added in one portion. Fifteen minutes later, a continuous feed was mounted for 2 hours of a solution containing: - 180 g of isopropyl acetate, - 274 g of butyl acrylate, and - 0.5 g of AIBN. The temperature and stirring were maintained for 1 hr 45 minutes after the end of the addition of the first monomer.

A small fraction of the precursor polymer was taken, and analyzed by G.P.C. in a medium of THF, and in polystyrene equivalents: - Mn = 7,000, - Ip = 1.9. A second continuous feed was then mounted for 1 hour. It consisted of a solution that contained: - 10 g of isopropyl acetate, - 163 mg of ethyl acrylate, and - 0.32 g of AIBN. The temperature and the stirring were still maintained one hour after the end of the addition of the second monomer. The final copolymer was recovered by evaporation of solvent and traces of residual monomer, and analyzed by G.P.C. in the middle of THF and in polystyrene equivalents. The results are given in Table 12.

Example 3.19: Block copolymer of p (ABu-b-AEt) In a reactor provided with a stirring system were introduced: - 45 g of isopropyl acetate, - 75 g of butyl acrylate, and - 6.9 g of a- (O- eti Ixanti 1) ethyl propionate.

The temperature was brought to 80 ° C, and 0.15 g of AIBN in solution in 5 g of isopropyl acetate were added in one portion. Twenty minutes later, a continuous feed was mounted for 1 hour 30 minutes of a solution containing: - 117 g of isopropyl acetate, - 175 g of butyl acrylate, and - 0.35 g of AIBN. The temperature and stirring were maintained for 2 hours 10 minutes after the end of the addition of the first monomer. A small fraction of the precursor polymer was taken, and analyzed by G.P.C. in a medium of THF, and in polystyrene equivalents: - Mn = 5,200, - Ip = 1.8. A second continuous feed was then mounted for 1 hour 40 minutes. It consisted of a solution containing: - 168 g of isopropyl acetate, - 252 mg of ethyl acrylate, and - 0.5 g of AIBN. The temperature and the stirring were still maintained 20 minutes after the end of the addition of the second monomer. The final copolymer was recovered by evaporation of solvent and traces of residual monomer, and analyzed by G.P.C. in the middle of THF and in polystyrene equivalents. The results are given in Table 12. Results of Examples 3.1 to 3.19. Table 12 E emplos Monomers Mn ip Conversion rate MY M2 M3 E. 3.1 AMe St - 4,650 1.6 Ex. 3.2 st AMe - 4, 300 1.7 Ex. 3.3 St AMe - 4, 200 1.8 Ex. 3.4 St AMe St 6,200 2 Ex. 3.5 AMe St - 3,750 1.8 Ex. 3.6 AEt AVM - 5, 600 1.4 92.3% Ex. 3.7 AEt AtBu - 6,800 1.7 97.8% Ex. 3.8 AtBu AVM - 6, 900 1.5 83.8% Ex. 3.9 AtBu AEt - 7, 000 2.0 96.1% Ex. 3.10 AEt St - 7,600 1.8 98.4% Ex. 3.11 AtBu St - 8,100 2.9 95.9% Ex. 3.12 AEt AtBu St 13,000 2.4 97.5% Ex. 3.13 St AEt - 6,200 1.9 > 99% Ex. 3.14 St AtBu - 7,100 1.9 > 99% Ex. 3.15 AtBu AEt st 11,400 2.4 > 99% Ex. 3.17 AtBu AVM - 7,400 1.4 88% Ex. 3.18 ABu AEt - 8,700 2.2 95% Ex. 3.19 ABu AEt - 10, 000 2.0 80%

Claims (22)

1. CLAIMS 1. Polymerization process for polymers in blocks of general formula (I): wherein: - Z1 = S or P, - Z2 = O, S or P, - R1 and R2, identical or different, represent: - a group (i) alkyl, acyl, aryl, alkene or optionally substituted alkyne, or - a cycle (ii) of carbon, saturated or not, optionally substituted or aromatic, or a heterocyclo (iii), saturated or not, optionally substituted, these groups or cycles (i), (ii) and (iii) can to be substituted by substituted phenyl groups, substituted aromatic groups or groups: alkoxycarbonyl or aryloxycarbonyl (-C00R), carboxy (-COOH), acyloxy (-02CR), carbamoyl (-C0NR2), cyano (-CN), alkylcarbonyl, alkylarylcarbonyl, arylcarbonyl , arylalkylcarbonyl, phthalimido, maleimido, succinimido, amidino, guanidino, hydroxy (-0H), amino (-NR2), halogen, allyl, epoxy, alkoxy (-OR), S-alkyl, S-aryl; groups having a hydrophilic or ionic character such as the alkali metal salts of carboxylic acids, the alkali salts of the sulphonic acid, the alkylene polyoxide chains (POE, POP), the cationic substituents (quaternary ammonium salts), R represents an alkyl or aryl group, a polymer chain, 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 R3, OR3, OCOR3, NHCOH, OH, NH2, NHR3, N (R3) 2, (R3) 2N + 0 ~, NHCOR3, C02H, C02R3, CN, CONH2, CONHR3 or CONR32, in wherein R3 is selected from alkyl, aryl, aralkyl, alkaryl, alkene or organosilyl groups, optionally perfluorinated and optionally substituted by one or more carboxyl, epoxy, hydroxyl, alkoxy, amino, halogen or sulphonic groups, a and b, identical or different, are 0 or 1, myn, identical or different, are superior or equal to 1, and when one or the other is greater than 1 the repetitive unit groups are identical, procedure in which they are put in contact: an ethylenically unsaturated monomer of formula CYY '(= CW-CW) a = CH2, - a precursor compound of general formula (II): - a radical polymerization initiator.
2. 2. Method according to claim 1, characterized in that the ethylenically unsaturated monomer is selected from: styrene or its derivatives, butadiene, chloroprene, (meth) acrylic esters and vinyl nitriles.
3. Method according to the preceding claim, characterized in that the ethylenically unsaturated monomer is selected from vinyl acetate, vinyl versatate, and vinyl propionate
4. 4. Method according to any of the preceding claims, characterized because R1 represents: - a group of formula CR'1R'2R'3, in which: R'1, R '2 and R' 3 represent groups (i), (ü) or (iii) such as defined above , or - R '1 = R' 2 = H and R '3 is an aryl, alkene or alkyne group, or a -COR' group in which R4 represents a group (i), (ii) or (iii).
5. 5. A method according to any of the preceding indications, characterized in that R2 preferably represents a group of the formula: -CH2R'3, in which R5 represents H or a group (i), (ii) or (iii) with the exception of the aryl, alkyne and alkene groups.
6. Method according to any of the preceding claims, characterized in that Z1 is a sulfur atom and Z2 is an oxygen atom.
7. 7. Method according to the preceding claim, characterized in that: - R1 is selected from the groups: 'H I - C - CH3 I C02Et H I - C - CH3 I f enyl H I C - C02Et I C02Et CH3 I C - S - phenyl I COzEt and R is an ethyl or phenyl group.
8. 8. Process according to any of the preceding claims, characterized in that the compounds (II) are selected from the homopolymers of styrene (Y '= H, Y = C5H5, b = 0), of methyl acrylate (Y' = H, Y = COOMe, b = 0), of ethyl acrylate (Y '= H, Y = COOEt, b = 0), of butyl acrylate (? '= H, Y = COOBu, b = 0), of tert-butyl acrylate (?' = H, Y = COOtBu, b = 0), of vinyl acetate (? '= H, Y = OCOMe, b = 0), of acrylic acid (? '= H, Y = COOH, b = 0), for which: - Z1 = S, Z2 = O, R1 = CHCH3 (C0¿Et) and R2 = Et, or - Z1 = S, Z2 = O, R1 = CH (COzEt) 2 and R2 = Et.
9. 9. Process according to any of the preceding claims, characterized in that the precursor compound of general formula (II) is a polymer, and because the polymer is obtained from the radical polymerization of an ethylenically unsaturated monomer of formula CXX '(= CV -CV) b = C¾ in the course of which the monomer is contacted with a radical polymerization initiator and a compound "of general formula (III), (IV) or (V): c-z1 - R1 OID / R2 - Z2 R2- - Z2 - C - Z - R1) p (IV) II S R - Z1 - C - Z2 - R2) p (V) II s p is between 2 and 10.
10. 10. Process according to the preceding claim, characterized in that the compound (III) is selected from ethyl a- (O-ethylxanthyl) ropionate (Z1 = S, Z2 = O, R1 = CHCH3 (C02Et) and R2 = Et) and [1- (O-ethylxanthyl) malonate (Z1 = S, Z2 = 0, R1 = CH (C02Et) 2, R2 = Et).
11. 11. Process for preparing block polymers, characterized in that the application of the process according to any of claims 1 to 10 is repeated at least once using: - monomers different from the previous application, and - instead of the parent compound of formula ( II), the block polymer obtained from the preceding application.
12. 12. Block polymers capable of being obtained by the process according to any of claims 1 to 10 or 11.
13. 13. Block polymer according to the preceding claim, characterized in that it has a polydispersity index of at most 2.
14. 14. Block polymer according to claim 12 or 13, characterized in that it has a polydispersity index of at most 1.5.
15. 15. Block polymer according to any of claims 12 to 14, characterized in that it is of general formula (I), in which Z1 is a sulfur atom and Zz is an oxygen atom.
16. 16. Block polymer according to any of claims 12 to 15, characterized in that they have at least two blocks of polymers selected from the following associations: - polystyrene / methyl acrylate, - polystyrene / ethyl polyacrylate, - polystyrene / terry polyacrylate butyl, - ethyl polyacrylate / vinyl polyacetate, - Butyl polyacrylate / vinyl polyacetate, - ethyl polyacrylate / tert-butyl polyacrylate, - tert-butyl polyacrylate / vinyl polyacetate, - ethyl polyacrylate / butyl polyacrylate, - Butyl polyacrylate / polyvinyl alcohol, - acrylic polyacid / polyvinyl alcohol.
17. 17. Block polymer according to claim 16, characterized in that it is of general formula (I), in which: - Z1 = S, Z2 = 0, R1 = CHCH3 (C02Et) and R2 = Et, or - Z1 = S, Z2 = O, R1 = CH (C02Et) 2 and R2 = Et.
18. 18. Polymer capable of being obtained by the process consisting in contacting an ethylenically unsaturated monomer of formula CXX '(= CV-CV') b = CH2, a radical polymerization initiator and a compound of general formula (III), ( IV) or (V).
19. 19. Polymer according to claim 18, characterized in that it has a polydispersity index of at most 2.
20. 20. Polymer according to claim 18 or 19, characterized in that it has a polydispersity index of at most 1.5.
21. 21. Polymer according to any of claims 18 to 20, characterized in that it is of the general formula (II) in which Z1 is an sulfur, Z2 is an oxygen atom, and because n is greater than or equal to 6.
22. 22. Polymer according to any of claims 20 or 21, characterized in that it is selected from the polymers of styrene (Y '= H, Y = C6H5, b = 0), of methyl acrylate (Y' = H, Y = COOMe, b = 0), of ethyl acrylate (Y '= H, Y = COOEt, b = 0), of butyl acrylate (Y' = H, Y = COOBu, b = 0), of tert-butyl acrylate ( Y '= H, Y = COOtBu, b = 0), of vinyl acetate (Y' = H, Y = OCOMe, b = 0), of acrylic acid (Y '= H, Y = COOH, b = 0) , for which: - Z1 = S, Z2 = O, R1 = CHCH3 (C02Et) and R2 = Et, O - Z1 = S, Z2 = O, R1 = CH (C02Et) 2 and R2 = Et.