FR2791687A1 - Polymerization of radical-polymerizable monomers, especially methyl methacrylate, comprises using a combination of a stable free radical and an electron donor for improved control - Google Patents

Abstract

Polymerization or copolymerization of radical-polymerizable monomers is effected in the presence of a stable free radical (I), an electron donor (II) and optionally an electron acceptor (III), the (II):(III) molar ratio being more than 1:1.

Description

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CONTROLLED RADICAL CONTROLLED POLYMERIZATION OR COPOLYMERIZATION METHOD
The present invention relates to a method of polymerization or controlled copolymerization of at least one radically polymerizable monomer.

 Radical polymerization is one of the most commercially exploited polymerization processes because of the variety of polymerizable monomers, the ease of implementation and the synthetic processes used (emulsion, suspension, mass, solution). However, it is difficult in conventional radical polymerization to control the size of the polymer chains as well as the molecular weight distribution.

Materials made of these macromolecules therefore do not have controlled physicochemical properties.

 The ionic or coordinative polymerizations make it possible, in turn, to control the monomer addition process, but they require careful polymerization conditions, especially a marked purity of the monomer and reagents, as well as an inert atmosphere.

 The aim is to be able to carry out radical polymerizations which better control the various parameters mentioned above and lead to polymers with a narrower polydispersity. It may be mentioned in this regard that the quality of a polymerization or copolymerization control can also be appreciated by observing the increase in the number-average molecular weight as a function of the percentage of conversion of the monomers to polymer or copolymer. When the control is good, the number average molecular weight is linearly proportional to the conversion percentage.

l'aide de la courbe ln(1/(1-conversion)) en fonction du temps et de l'indice de polymolécularité. Plus la courbe s'écarte de la linéarité, moins le contrôle est bon. Plus One can also appreciate the control of the polymerization to

using the ln (1 / (1-conversion)) curve as a function of time and the polymolecularity index. The more the curve deviates from linearity, the less control is good. More

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 the polymolecularity index is high, the less the control is good.

 Various techniques are currently known to control the radical polymerization. Among these techniques which are described in detail in the literature, two techniques are more particularly studied: # The first is the living radical polymerization by transfer of atoms or groups of atoms (ATRP), in the presence of a generator of radicals free, said reaction being generally promoted by transition metals. This technique makes it possible to control the polymerization of numerous monomers, such as acrylates, styrene, methacrylates, isobutene and acrylamide. However, residual metals can be troublesome for some applications.

 # The second is the living radical polymerization with thermal activation in the presence of stable free radicals such as nitroxide radicals (SFRP).

This technique is more specific to styrene. Indeed, by this technique, the polar monomers, acrylates or methacrylates, polymerize slowly or poorly when cyclic nitroxides (such as 2,2,6,6-tetramethyl-1-piperidinyloxy) are added. In the presence of specific noncyclic nitroxides such as those described in the European patent application EP-A-832 902, in particular N-tert-butyl-1-diethylphosphono-2,2-dimethylpropyl nitroxide, the acrylates can be effectively polymerized from in a controlled manner, but methacrylates, such as methyl methacrylate, can not be polymerized as effectively.

 Furthermore, PCT international application WO 96/35727 describes the controlled radical polymerization of vinyl monomers, such as styrene and methyl methacrylate, in the presence of radical initiators.

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 free and electron donors. However, the polydispersity indices obtained are still high, indicating that the control is far from optimal.

 The present invention aims to provide a method which will provide better control of the polymerization and which, therefore, will be advantageously applicable to the (co) polymerization of methacrylates and, in particular, methyl methacrylate. It is also known that poly (methyl methacrylate) is all the more resistant to thermal degradation as the polymerization of methyl methacrylate has been better controlled.

 In order to meet the desired objective, it is proposed, in accordance with the invention, to carry out the (co) polymerization both in the presence of at least one stable free radical and at least one electron donor.

It was not at all obvious that this combination of agents could have made it possible to reduce the polydispersity index of the polymers thus prepared and to ensure excellent control of the polymerization advantageously applying to methacrylates.

 It will also be emphasized that the control of the polymerization of methyl methacrylate is useful in the case where it is desired to manufacture cast slabs. Indeed, to avoid the formation of defects on the surface of the poly (methyl methacrylate) (PMMA) plates, it is necessary to subject the PMMA plates to particular temperature cycles so as not to be hindered by the gel effect (or Trommsdorf effect). Good control of the radical polymerization of methyl methacrylate is then very useful because the polymerization can be carried out at a single temperature, which is a saving time and facilitates the production of plates.

 The object of the present invention is therefore to provide a process for the polymerization or copolymerization of at least one radically polymerizable monomer in the presence of at least one stable free radical and at least one electron donor. in the presence of at least one

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 electron acceptor, the electron donor / electron acceptor (s) molar ratio being greater than 1.

dans lesquelles :
R1 à R3, R5 à R8 et R13 et R14 représentent chacun indépendamment : (a) un atome d'hydrogène ; (b) un atome d'halogène, tel que le chlore, le brome ou l'iode ; (c) un groupement hydrocarboné, saturé ou insaturé, linéaire, ramifié ou mono- ou polycyclique, et pouvant être substitué par au moins un halogène ; (d) un groupement ester -COOR15 ou un groupement alcoxyle -OR16, R15 et R16 représentant un groupement hydrocarboné tel que défini au point (c) ci-dessus ;

R17 (e) un groupement de formule ~ / 1 u-""""R18 o In particular, the stable free radical or radicals chosen from nitroxide radicals, that is to say containing the group = NO #, in particular from those of formulas (Ia), (Ib) or (le):

in which :
R1 to R3, R5 to R8 and R13 and R14 each independently represent: (a) a hydrogen atom; (b) a halogen atom, such as chlorine, bromine or iodine; (c) a hydrocarbon group, saturated or unsaturated, linear, branched or mono- or polycyclic, and may be substituted by at least one halogen; (d) an ester group -COOR15 or an alkoxyl group -OR16, R15 and R16 representing a hydrocarbon group as defined in (c) above;

R17 (e) a group of formula ~ / 1 u - """" R18 o

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de N-O', ledit hétérocycle pouvant être saturé ou insaturé, pouvant comporter dans le cycle au moins un

autre hétéroatome et/ou au moins un groupement #C# , et Il u pouvant également comporter un cycle accolé, saturé ou insaturé ; wherein R17 and R18 each independently represent a linear, branched or cyclic alkyl, perfluoroalkyl, aryl, aralkyl, alkaryl, alkoxyl, aryloxyl, aralkyloxyl, alkaryloxyl radical, which radicals may comprise from 1 to 20 carbon atoms; or halogen such as chlorine, bromine, fluorine or iodine; (f) a polymer chain which may, for example, be a poly (alkyl methacrylate) or poly (alkyl acrylate) chain, such as poly (methyl methacrylate), polydiene such as polybutadiene, polyolefin; as polyethylene or polybutadiene, but preferably being a polystyrene chain; - R4 has the meanings defined in (a), (b), (c), (d) and (f) above, and in the case where it is connected to the nitrogen atom by an atom of carbon, the latter may carry at least one group as defined in point (e) above; R 9 to R 12, which are identical or different, have the meanings defined in points (a) to (f) above and may furthermore represent a hydroxide group or an acidic group, such as -COOH, -PO (OH) 2 or -S03H; - Ret R4 can be interconnected, and - in the case where R4 represents a residue -CR'1R'2R'3 (R'1 to R'3 having indifferently the meanings of
R1 to R3) R3 may be connected to R'3 - to form a heterocycle containing the nitrogen atom

of N-O ', said heterocyclic ring being saturable or unsaturated, which may comprise in the ring at least one

another heteroatom and / or at least one group # C #, and Il u may also comprise a fused ring, saturated or unsaturated;

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 two of R1 to R3, R5 and R6, R7 and R8, R9 and R10, R11 and R12, R6 and R9, R8 and R11, R13 and R14 and - in the case where R4 represents a residue -CR RR, Ret R ' 3- can be independently connected to form, with the carbon atom that carries them, a saturated or unsaturated ring or heterocycle; u is a non-zero integer, for example from 1 to 18.

 As examples of the hydrocarbon groups as defined in (c) above, mention may be made of those having from 1 to 20 carbon atoms, such as linear, branched or cyclic alkyl radicals, and aryl radicals such as phenyl radicals. or naphthyl, and the radicals comprising at least one aromatic ring which may be substituted, for example, with a C 1 -C 4 alkyl radical, such as aralkyl radicals, such as benzyl.

dans laquelle le radical RL présente une masse molaire supérieure à 15. le radical RL, monovalent, est dit en position par rapport à l'atome d'azote du radical nitroxyde. Les valences restantes de l'atome de carbone et de l'atome d'azote dans la formule (1) peuvent être liées à des radicaux divers tels qu'un atome d'hydrogène, un radical hydrocarboné comme un radical alkyle, aryle ou aralkyle, comprenant de 1 à 10 atomes de carbone. Il n'est pas exclu que l'atome de carbone et l'atome d'azote dans la formule (1) soient reliés entre eux par l'intermédiaire d'un radical bivalent, de façon à former un cycle. De préférence cependant, les valences restantes de l'atome de carbone et de l'atome d'azote de la formule (1) sont liées à des radicaux monovalents. De préférence, le radical RL présente une masse molaire supérieure à 30. Le radical RL peut par exemple avoir une masse molaire comprise entre 40 et 450. In particular, mention may be made of nitroxide radicals comprising a sequence of formula:

in which the radical RL has a molar mass greater than 15. the radical RL, monovalent, is said in position relative to the nitrogen atom of the nitroxide radical. The remaining valences of the carbon atom and the nitrogen atom in the formula (1) can be linked to various radicals such as a hydrogen atom, a hydrocarbon radical such as an alkyl, aryl or aralkyl radical. , comprising from 1 to 10 carbon atoms. It is not excluded that the carbon atom and the nitrogen atom in the formula (1) are connected to each other via a divalent radical, so as to form a ring. Preferably, however, the remaining valencies of the carbon atom and the nitrogen atom of the formula (1) are attached to monovalent radicals. Preferably, the radical RL has a molar mass greater than 30. The radical RL can for example have a molar mass of between 40 and 450.

By way of example, the radical RL can be a radical

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dans laquelle R1 et R2, pouvant être identiques ou différents, peuvent être choisis parmi les radicaux alkyle, cycloalkyle, alcoxyle, aryloxyle, aryle, aralkyloxyle, perfluoroalkyle, aralkyle, et peuvent comprendre de 1 à 20 atomes de carbone. R1 et/ou R2 peuvent également être un atome d'halogène comme un atome de chlore ou de brome ou de fluor ou d'iode. le radical RL peut également comprendre au moins un cycle aromatique comme pour le radical phényle ou le radical naphtyle, ce dernier pouvant être substitué, par exemple par un radical alkyle comprenant de 1 à 4 atomes de carbone. comprising a phosphoryl group, said radical RL being represented by the formula:

wherein R1 and R2, which may be the same or different, may be selected from alkyl, cycloalkyl, alkoxyl, aryloxyl, aryl, aralkyloxy, perfluoroalkyl, aralkyl, and may include from 1 to 20 carbon atoms. R1 and / or R2 may also be a halogen atom such as a chlorine or bromine or fluorine or iodine atom. the RL radical may also comprise at least one aromatic ring as for the phenyl radical or the naphthyl radical, the latter may be substituted, for example by an alkyl radical comprising from 1 to 4 carbon atoms.

A particular family of nitroxide radicals which may be envisaged according to the present invention is that of the nitroxide radicals of formula (Ia) in which R3 and R4 (or R3 and R'3) are connected to one another and which are chosen in particular from:

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où : - Ra à Rk et Rm ont indépendamment les significations données pour R9 à R12, les Ra et Rb et Re et Rf pouvant être identiques ou différents lorsqu'ils sont portés par des atomes de carbone différents ; - r vaut 2 ou 3 ou 4 ; - s est un entier non nul, en particulier de 1 à 10 ; - t vaut 0, 1 ou 2.

where: Ra to Rk and Rm independently have the meanings given for R9 to R12, Ra and Rb and Re and Rf may be the same or different when carried by different carbon atoms; r is 2 or 3 or 4; s is a non-zero integer, in particular from 1 to 10; t is 0, 1 or 2.

# le 3-carboxy-2,2,5,5-tétraméthyl-pyrrolidinyloxy (communément appelé 3-carboxy PROXYL) ; On the other hand, as particular examples of nitroxide radicals, the following may be indicated: # 2,2,5,5 tetramethyl-1-pyrrolidinyloxy (generally sold under the tradename PROXYL):

# 3-carboxy-2,2,5,5-tetramethylpyrrolidinyloxy (commonly known as 3-carboxy PROXYL);

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# le 4-hydroxy-2,2,6,6-tétraméthyl-1-pipéridinyloxy (communément appelé le 4-hydroxy-TEMPO) ; # le 4-méthoxy-2,2,6,6-tétraméthyl-1-pipéridinyloxy (communément appelé le 4-méthoxy-TEMPO) ; # le 4-oxo-2,2,6,6-tétraméthyl-1-pipéridinyloxy (communément appelé le 4-oxo-TEMPO) ; # le bis-(1-oxyl-2,2,6,6-tétraméthylpipéridine-4- yl) sébacate, représenté par la formule :

(commercialisé sous la marque "CXA 5415" par la Société "CIBA SPECIALTY CHEMICAL") ; # le 2,2,6,6-tétraméthyl-4-hydroxypipéridine-1- oxyl)monophosphonate :

# le N-tertiobutyl-1-diéthylphosphono-2,2-diméthyl propyl nitroxyde (DEPN) :

# 2,2,6,6-tetramethyl-1-piperidinyloxy (commonly known as TEMPO):

# 4-hydroxy-2,2,6,6-tetramethyl-1-piperidinyloxy (commonly known as 4-hydroxy-TEMPO); 4-methoxy-2,2,6,6-tetramethyl-1-piperidinyloxy (commonly known as 4-methoxy-TEMPO); # 4-oxo-2,2,6,6-tetramethyl-1-piperidinyloxy (commonly known as 4-oxo-TEMPO); bis- (1-oxyl-2,2,6,6-tetramethylpiperidin-4-yl) sebacate, represented by the formula:

(sold under the trademark "CXA 5415" by the company "CIBA SPECIALTY CHEMICAL"); 2,2,6,6-tetramethyl-4-hydroxypiperidin-1-oxyl) monophosphonate:

# N-tert-butyl-1-diethylphosphono-2,2-dimethylpropyl nitroxide (DEPN):

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# le N-(l-phénylbenzyl)-[(l-diéthylphosphono)-l-méthyl éthyl] nitroxyde :

# le N-phényl-1-diéthylphosphono-2,2-diméthyl propyl nitroxyde ; # le N-phényl-1-diéthylphosphono-1-méthyl éthyl nitroxyde ; # le N-(l-phényl 2-méthyl propyl)-1-diéthylphosphono-1- méthyl éthyl nitroxyde ; # le N-tertiobutyl-1-phényl-2-méthyl propyl nitroxyde :

# le N-tertiobutyl-l-(2-naphtyl)-2-méthyl propyl nitroxyde. # N-tert-butyl-1-dibenzylphosphono-2,2-dimethylpropyl nitroxide; # N-tertiobutyl-1-di (2,2,2-trifluoroethyl) phosphono-
2,2-dimethylpropyl nitroxide; # N-tert-butyl - [(1-diethylphosphono) -2-methylpropyl] nitroxide; N- (1-methylethyl) -1-cyclohexyl-1- (diethylphosphono) nitroxide:

N- (1-phenylbenzyl) - [(1-diethylphosphono) -1-methylethyl] nitroxide:

# N-phenyl-1-diethylphosphono-2,2-dimethylpropyl nitroxide; # N-phenyl-1-diethylphosphono-1-methyl ethyl nitroxide; N- (1-phenyl-2-methylpropyl) -1-diethylphosphono-1-methylethyl nitroxide; # N-tert-butyl-1-phenyl-2-methylpropyl nitroxide:

# N-tert-butyl-1- (2-naphthyl) -2-methylpropyl nitroxide.

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 Non-nitroxide stable radicals may also be 2,4,6-tri-tert-butylphenoxy.

As for the electron donors, they can be chosen in particular from the compounds of the formulas:

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où : - A représente le soufre ou le sélénium ; - R20 à R23 représentent chacun indépendamment un atome d'hydrogène ; alkyle en C1-C20, de préférence en

C1-C6 ; alcoxy en C1-C20' de préférence en Cl-C6 ; ou aryle en C6-C18, de préférence phényle ; - Y représente l'oxygène ou le soufre ; - R24 représente alkyle en C1-C20, de préférence en C1-C6 ; alcoxy en C1-C20, de préférence en C1-C6 ; ou aryle en C6-C18, de préférence phényle ; - n est un entier de 2 à 6 ;

where: A represents sulfur or selenium; - R20 to R23 each independently represent a hydrogen atom; C1-C20 alkyl, preferably

C1-C6; C1-C20 'alkoxy, preferably C1-C6 alkoxy; or C 6 -C 18 aryl, preferably phenyl; Y represents oxygen or sulfur; - R24 represents C1-C20 alkyl, preferably C1-C6 alkyl; C1-C20 alkoxy, preferably C1-C6 alkoxy; or C 6 -C 18 aryl, preferably phenyl; n is an integer of 2 to 6;

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- R26 représente un atome d'hydrogène, un reste alkyle en
C1-C5, -CF3, un atome d'halogène,-CN, -SR28, -OR28 ou -NR29R30 ;

#avec R 28à R30 représentant chacun alkyle en C1-C25, de préférence en C1-C10, comme méthyle, éthyle, n-propyle, i-propyle, n-butyle, i-butyle ou t-butyle ; ou aryle en C6-C18, comme phényle ; # l'un parmi R29 et R30 pouvant en outre représenter un atome d'hydrogène ; # R29 et R30 pouvant former conjointement avec l'atome d'azote auquel ils sont liés un noyau cyclo-N- aliphatique en C.-C, de préférence en C5-C6, non substitué ou substitué par au moins un groupe alkyle en C1-C5, et pouvant être interrompu par au moins l'un

parmi -O-, -S- ou -N- ; R 131 # R31 représentant un reste alkyle en C1-C10, de préférence en C1-C5 ; Z represents oxygen, sulfur or selenium; R 25 represents a hydrogen atom or a radical of formula: -BD in which: B represents a linear or branched C1-C25 alkylene radical, preferably an alkylene radical of
C1-C10, such as methylene, ethylene, 2-methyl ethylene, n-propylene or n-butylene; D represents -OH, -OR28, -SR28 or -NR29R30 or a C4-C7 cycloaliphatic residue which may be interrupted by at least one of -O-, -S- or

R 26 represents a hydrogen atom, an alkyl radical
C1-C5, -CF3, a halogen atom, -CN, -SR28, -OR28 or -NR29R30;

with R 28 to R 30 each representing C 1 -C 25 alkyl, preferably C 1 -C 10 alkyl, such as methyl, ethyl, n-propyl, i-propyl, n-butyl, i-butyl or t-butyl; or C6-C18 aryl, such as phenyl; one of R29 and R30 may further represent a hydrogen atom; # R29 and R30 may form, together with the nitrogen atom to which they are bonded, a cyclo-N-aliphatic ring C.sub.1 -C.sub.4, preferably C.sub.5 -C.sub.6, unsubstituted or substituted with at least one C.sub.1 -C.sub.6 alkyl group -C5, and can be interrupted by at least one

among -O-, -S- or -N-; R 131 # R31 representing a C1-C10 alkyl, preferably C1-C5 alkyl;

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 R27 and R32 to R35 each independently represent a hydrogen atom; a C1-C20, preferably C1-C6, alkyl radical; or a C6-C18 aryl residue, preferably phenyl; m is 0 or is an integer of 1 to 4; q is 0, 1 or 2; p is an integer from 2 to 100.

ou le composé de formule :

In particular, it is possible to use, as electron donors, tetrathiafulvalene of formula:

or the compound of formula:

The electron acceptors, which are optional in accordance with the present invention, may be chosen from quinodimethan compounds, anthraquinodimethanes compounds, fluorenylidene compounds, ferrocene compounds, nitroarene compounds, cyanoarene compounds, aromatic compounds having from 6 to 24 carbon atoms and having electron withdrawing substituents selected from the group consisting of cyano and nitro and mixtures thereof; mention may also be made of tetracyano-quinodimethane (TCNQ), 7,7-dicyanoquinomethane, nitro-9-fluorenone compounds, nitro-9-fluorenylene compounds, nitroarene compounds and analogous compounds.

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dans laquelle : - T et T' représentent chacun indépendamment cyano, alcoxycarbonyle ou des paires d'électrons associées à un substituant atome d'oxygène de type oxo ; - W représente un atome de carbone ou un atome d'oxygène ; - E, G et U sont des groupes extracteurs d'électrons choisis indépendamment parmi acyle, alcoxycarbonyle, nitro, alkylaminocarbonyle et leurs dérivés ; - a est un nombre de 0 à 2 ; - b vaut 0 ou 1 ; - U est un groupe extracteur d'électrons choisis parmi acyle (COR36), alcoxycarbonyle (-C-0-R36), alkylamino-
O carbonyle (CONHR36) et leurs dérivés, R36 représentant alkyle en C1-C20 éventuellement substitué. In particular, there may be mentioned compounds of formula:

wherein: T and T 'each independently represent cyano, alkoxycarbonyl or electron pairs associated with an oxo-type oxygen atom substituent; - W represents a carbon atom or an oxygen atom; E, G and U are electron withdrawing groups independently selected from acyl, alkoxycarbonyl, nitro, alkylaminocarbonyl and their derivatives; a is a number from 0 to 2; b is 0 or 1; U is an electron withdrawing group selected from acyl (COR36), alkoxycarbonyl (-C-O-R36), alkylamino-
O carbonyl (CONHR36) and their derivatives, R36 representing optionally substituted C1-C20 alkyl.

où R est un groupe alkyle en C1-C20' aralkyle en C7-C20, aryle en C6-C20 et leurs dérivés substitués par oxygène, soufre, phosphore ou halogène. In particular, compounds of formula

wherein R is C 1 -C 20 alkyl, C 7 -C 20 aralkyl, C 6 -C 20 aryl and derivatives thereof substituted with oxygen, sulfur, phosphorus or halogen.

In particular mention is made of 4-butyloxycarbonyl-9-fluorenylidenemalonitrile where R is an n-butyl group.

 Mention may also be made of the compounds of the formulas:

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où : - R37 et R38 représentent indépendamment alkyle en

ci-c20 ; - c et d valent chacun 0 ou un entier de 1 à 4 ; - e et f valent chacun 0 ou un entier de 1 à 4.

where: - R37 and R38 independently represent alkyl in

c-20; - c and d are each 0 or an integer of 1 to 4; e and f are each 0 or an integer from 1 to 4.

 The molar ratio -NO / monomer or mixture of monomers is advantageously between 0.00001 and 1, preferably between 0.00005 and 0.5. The molar ratio of the donor (s) of electrons / monomer or monomer mixture is advantageously between 0.00001 and 1, preferably between 0.00005 and 0.5.

 In the context of the present invention, any monomer having a carbon-carbon double bond capable of radical polymerization or copolymerization can be used.

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 The monomer (s) can thus be chosen from vinyl, allylic, vinylidene, diene and olefinic monomers.

 By vinyl monomers is meant (meth) acrylates, vinylaromatic monomers, vinyl esters, vinyl ethers, (meth) acrylonitrile, (meth) acrylamide and mono- and di- (C1-C18) alkyl - (meth) acrylamides, and the monoesters and diesters of maleic anhydride and maleic acid.

dans lesquelles R0 est choisi parmi les radicaux alkyle en C1-C18, linéaires ou ramifiés, primaires, secondaires ou tertiaires, cycloalkyle en C5-C18, (alcoxy en C1-C18)-alkyle en C1-C18, (alkylthio en C1-C18)-alkyle en C1-C18, aryle et arylalkyle, ces radicaux étant éventuellement substitués par au moins un atome d'halogène et/ou au moins un groupe hydroxyle, les groupes alkyle ci-dessus étant linéaires ou ramifiés ; et les (méth) acrylates de glycidyle, de norbornyle, d'isobornyle. # The (meth) acrylates are in particular those of the formulas respectively:

wherein R 0 is selected from linear or branched, primary, secondary or tertiary C 1 -C 18 alkyl, C 5 -C 18 cycloalkyl, (C 1 -C 18) alkoxy-C 1 -C 18 alkyl, (C 1 -C 18) alkylthio C1-C18alkyl, aryl and arylalkyl, said radicals being optionally substituted by at least one halogen atom and / or at least one hydroxyl group, the above alkyl groups being linear or branched; and glycidyl, norbornyl, isobornyl (meth) acrylates.

phényle, de benzyle, de 3~hydroxy-éthyle, d'isobornyle, d'hydroxypropyle, d'hydroxybutyle. On peut citer en particulier le méthacrylate de méthyle. As examples of useful methacrylates, mention may be made of methyl, ethyl, 2,2,2-trifluoroethyl, n-propyl, isopropyl, n-butyl and sec methacrylates. butyl, tert.-butyl, n-amyl, i-amyl, n-hexyl, 2-ethylhexyl, cyclohexyl, octyl, i-octyl, nonyl, decyl, lauryl, stearyl,

phenyl, benzyl, 3-hydroxyethyl, isobornyl, hydroxypropyl, hydroxybutyl. Mention may in particular be made of methyl methacrylate.

 As examples of acrylates of the formula above, mention may be made of methyl, ethyl, n-propyl, isopropyl, n-butyl and dry acrylates. butyl, tert.-butyl, hexyl, 2-ethylhexyl, isooctyl,

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 3,3,5-trimethylhexyl, nonyl, isodecyl, lauryl, octadecyl, cyclohexyl, phenyl, methoxymethyl, methoxyethyl, ethoxymethyl and ethoxyethyl.

 By vinylaromatic monomer in the sense of the present invention is meant an aromatic monomer with ethylenic unsaturation such as styrene, vinyltoluene, alphamethylstyrene, methyl-4-styrene, methyl-3-styrene, methoxy-4- styrene, hydroxymethyl-2-styrene, ethyl-4-styrene, ethoxy-4-styrene, dimethyl-3,4-styrene, styrenes substituted on the halogen ring, such as chloro-2 styrene, chloro-3-styrene, chloro-4-methyl-3-styrene, tert-butyl-3-styrene, 2,4-dichloro-styrene and 2,6-dichloro-styrene; vinyl-1-naphthalene and vinylanthracene.

 As vinyl esters, there may be mentioned vinyl acetate, vinyl propionate, vinyl chloride and vinyl fluoride, and vinyl ethers include vinyl methyl ether and vinyl ethyl ether.

 As the vinylidene monomer, vinylidene fluoride is mentioned.

 By diene monomer is meant a diene chosen from linear or cyclic dienes, conjugated or non-conjugated, such as butadiene, 2,3-dimethylbutadiene, isoprene, 1,3-pentadiene, 1, 4-pentadiene, 1,4-hexadiene, 1,5-hexadiene, 1,9-decadiene, 5-methylene-2-norbornene, 5-vinyl-2-norbornene, 2-alkyl-2, 5-Norbornadienes, 5-ethylene-2-norbornene, 5- (2-propenyl) -2-norbornene, 5- (5-hexenyl) -2-norbornene, 1,5-cyclooctadiene, bicyclo [2 , 2,2] octa-2,5-diene, cyclopentadiene, 4,7,8,9-tetrahydroindene, isopropylidene tetrahydroindene and piperylene.

 Olefinic monomers include ethylene, butene, hexene and 1-octene. The fluorinated olefinic monomers can also be mentioned.

 As the (co) polymerizable monomer, mention may also be made of maleic anhydride; mention is made more particularly of the styrene / maleic anhydride mixture,

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 leading to alternating styrene / maleic anhydride copolymers also called SMA # resins.

 The process according to the present invention is more particularly effective in the case of methacrylates, for example methacrylates of methyl, ethyl, butyl, stearyl, in particular methyl methacrylate.

 The polymerization or copolymerization of the invention is carried out under the usual conditions known to those skilled in the art taking into account the monomer or monomers considered, as long as this polymerization or copolymerization takes place by a radical mechanism, and with the difference that adds to the medium the stable free radical (s) and electron donor (s) according to the invention. Depending on the nature of the monomer or monomers that it is desired to polymerize or copolymerize, it may be necessary to introduce into the polymerization or copolymerization medium at least one initiator of free radicals. Those skilled in the art know the monomers that require the presence of such an initiator for this monomer to polymerize or copolymerize. For example, the polymerization or copolymerization of a diene requires the presence of a free radical initiator.

 The free radical initiator (s) can be introduced into the polymerization or copolymerization medium at a rate of 0.001 to 10% by weight and, preferably, from 0.01 to 1% by weight, relative to the monomer or to the mixture of monomers. .

 Free radical initiators may, for example, be selected from those of peroxide type, hydroperoxide type or azo type. By way of examples, mention may be made of the following initiators: benzoyl peroxide, lauroyl peroxide, cumyl hydroperoxide, tert-butyl peracetate, tertiary perpivalate. amino, butyl per-2-ethylhexanoate, tert-butyl perpivalate, tert-butyl perneodecanoate, tert-butyl perisononanoate, tert-butyl perneodecanoate. amino, tert.-butyl perbenzoate, di-2-ethylhexyl peroxydicarbonate,

<Desc / Clms Page number 21>

 dicyclohexyl peroxydicarbonate, cumyl perneodecanoate, tert.-butyl permaleate, 2,2'-azobis (isobutyronitrile), 2,2'-azobis (2,4-dimethyl-valeronitrile), 2,2'-azobis ( cyclohexanenitrile), 2,2'-azobis- (2-methylbutyronitrile), 2,2'-azobis (2,4-dimethyl-4-methoxyvaleronitrile).

rapport molaire -NO'/amorceur(s) de radicaux libres est avantageusement compris entre 0,1 et 10, plus particulièrement entre 0,5 et 5 ; le rapport molaire donneur(s) d'électrons/amorceur(s) de radicaux libres est avantageusement compris entre 0,1 et 10, plus particulièrement entre 0,5 et 5. According to other particular features of the present invention, when at least one free radical initiator is introduced into the medium, the

molar ratio -NO '/ initiator (s) of free radicals is advantageously between 0.1 and 10, more particularly between 0.5 and 5; the molar ratio of the donor (s) of electrons / initiator (s) of free radicals is advantageously between 0.1 and 10, more particularly between 0.5 and 5.

 Moreover, in the case where at least one electron acceptor is present, the molar ratio electron donor (s) / acceptor (s) of electrons is, as already indicated, greater than 1; such a ratio may in particular be greater than 2. It goes without saying that the electron acceptor may be absent.

 The polymerization or copolymerization according to the invention is generally carried out in a temperature range from 0.degree. C. to 200.degree. C., and preferably from 50.degree. C. to 150.degree.

 Furthermore, the polymerization or copolymerization of the invention can be carried out in bulk, in solution, in emulsion or in suspension. The preferred routes are in solution and in suspension. The polymerization of methyl methacrylate in suspension can be useful for obtaining powders of various diameters.

 Depending on the conditions of polymerization or copolymerization, and in particular the duration, the temperature, the degree of conversion of monomer to polymer or copolymer, it is possible to produce products of different molecular masses.

<Desc / Clms Page number 22>

 The invention relates to both the preparation of oligomers, polymers or copolymers having a weight average molecular weight of less than 10,000, and to polymers or copolymers having a weight average molecular weight greater than 10,000, such as high polymers of weight average molecular weight generally ranging from 100,000 to 400,000. The polydispersity index of the polymers or copolymers of the invention is also generally less than 1.5.

 Reference examples and non-limiting examples describing the preparation of polymers as obtained according to the method of the present invention are given below.

 The values of the experimental Mnexp number average molecular weight and the Mw / Mn polydispersity or polymolecularity index are obtained in the following manner. Steric exclusion chromatography (SEC) is used which separates the macromolecules from the polymer. according to their size in solutioh (hydrodynamic volume). They are then eluted with a solvent (THF mobile phase) of the polymer. Larger molecules come out first and smaller ones last because of the longer path in the pores of the column (stationary phase). PMMA of known absolute masses (determined by another technique) are also injected (standards) and make it possible to obtain a calibration curve from which the relative molecular weights (Mnexp) of the polymer whose determination is to be made are determined. size and mass distribution or polydispersity (Mw / Mn).

Mntheo= [M] /2 [amorceur] xconversion en %/lOOxMasse molaire de M en g/mole. The theoretical number average molecular weights (Mnthéo) are calculated from the molar ratio monomer / initiator, corrected by the yield:

Mntheo = [M] / 2 [initiator] xconversion in% / 100xMolecar m from M to g / mole.

<Desc / Clms Page number 23>

[M] being the monomer concentration and [initiator] being the initiator concentration.

 The above formula takes into account the case of an initiator which theoretically releases two moles of free radicals per mole of initiator.

 The factor f is the molecular weight control factor Mnthéo / Mnexp.

In these examples, the following abbreviations have been used: # MMA: methyl methacrylate # PMMA: poly (methyl methacrylate) # AIBN: azobisisobutyronitrile # DEPN: nitroxide de.formule.

Example 1 (reference)
Uncontrolled polymerization of MMA
3.7 g (4 ml) of MMA and 15.4 mg of AIBN are mixed in a Schlenk tube equipped with magnetic stirring and degassing is carried out in order to remove the residual oxygen. The mixture is then heated to the desired temperature of 90 ° C. The polymerization is stopped after two hours, after which time 95% of the MMA has been converted.

 The Mnthéo is 20,000 g / mole, and the Mnexp is 16,300 g / mole. Mw / Mn = 2.

 The polymerization is very fast and poorly controlled as indicated by the polymolecularity.

<Desc / Clms Page number 24>

Example 2 (reference)
Controlled polymerization of MMA with DEPN
3.6 g (3.8 ml) of MMA, 14.5 mg of AIBN and 93.1 mg of DEPN at 71% purity (molar ratio DEPN) are mixed in a Schlenk tube provided with magnetic stirring. / AIBN = 2.55) and the mixture is heated to the desired temperature of 90 ° C. The time at which the mixture reaches the temperature of 90 ° C. is defined as the start time of the test. Samples are taken over time. This makes it possible to calculate the conversion to polymer obtained after evaporation under vacuum. (0.01 mbar, 100 C, 30 min.) Of the monomer remaining in a sample. The Mnthéo at 100% conversion is 20,000 g / mole.

 The results are reported in Table 1.

TABLE 1

<tb> Time <SEP> Conversion <SEP> 1
<Tb>
<Tb>
<Tb>
<tb> (time) <SEP> (%) <SEP> ln (<SEP>)
<Tb>
<Tb>
<Tb>
<tb> 1-Conversion
<Tb>
<Tb>
<Tb>
<Tb>
<Tb>
<Tb>
<Tb>
<tb> 0 <SEP> 0 <SEP> 0
<Tb>
<Tb>
<Tb>
<Tb>
<Tb>
<Tb>
<Tb>
<Tb>
<Tb>
<tb> 1.5 <SEP> 41 <SEP> 0.53
<Tb>
<Tb>
<Tb>
<Tb>
<Tb>
<Tb>
<Tb>
<tb> 2.5 <SEP> 42 <SEP> 0.54
<Tb>
<Tb>
<Tb>
<Tb>
<Tb>
<Tb>
<Tb>
<Tb>
<tb> 6 <SEP> 44 <SEP> 0.58
<Tb>
<Tb>
<Tb>
<Tb>
<Tb>
<Tb>
<Tb>
<tb> 10.25 <SEP> 44 <SEP> 0.58
<Tb>
<Tb>
<Tb>
<Tb>
<Tb>
<Tb>
<Tb>
<Tb>
<tb> 12.25 <SEP> 48 <SEP> 0.65
<Tb>
<Tb>
<Tb>
<Tb>
<Tb>
<Tb>
<Tb>
<Tb>
<tb> 15.5 <SEP> 48 <SEP> 0.65
<Tb>
<Tb>
<Tb>
<Tb>
<Tb>
<Tb>
<Tb>
<tb> 19.5 <SEP> 52 <SEP> 0.73
<Tb>
<Tb>
<Tb>
<Tb>
<Tb>
<Tb>
<Tb>
<Tb>
<tb> 23.75 <SEP> 63 <SEP> 0.99
<Tb>

The polymerization is poorly controlled, and the polymerization rate is low.

<Desc / Clms Page number 25>

Example 3 (reference)
Controlled polymerization of MMA with TTF
4.7 g (5 ml) of MMA, 20.0 mg of AIBN and 48 mg of TTF (molar ratio TTF / AIBN = 1.9) are mixed in a Schlenk tube provided with magnetic stirring. heats the mixture to the desired temperature of 90 ° C.

The time at which the mixture reaches 90 C is defined as the start time of the test. Samples are taken over time. This makes it possible to calculate the conversion to polymer obtained after evaporation under vacuum. (0.01 mbar, 100 C, 30 min.) Of the monomer remaining in a sample. The Mnthéo at 100% conversion is 20,000 g / mole.

 The results are reported in Table 2.

TABLE 2

<tb> Time <SEP> Conversion <SEP> 1
<Tb>
<Tb>
<tb> (time) <SEP> (%) <SEP> In <SEP>)
<Tb>
<Tb>
<Tb>
<tb> 1-Conversion
<Tb>
<Tb>
<Tb>
<Tb>
<Tb>
<Tb>
<Tb>
<tb> 0 <SEP> 0 <SEP> 0
<Tb>
<Tb>
<Tb>
<Tb>
<Tb>
<Tb>
<Tb>
<tb> 1 <SEP> 74 <SEP> 1.35
<Tb>
<Tb>
<Tb>
<Tb>
<Tb>
<Tb>
<Tb>
<tb> 3 <SEP> 83 <SEP> 1.77
<Tb>
<Tb>
<Tb>
<Tb>
<Tb>
<Tb>
<Tb>
<tb> 5 <SEP> 85 <SEP> 1.90
<Tb>

The polymerization rate is higher than that obtained in Example 2, but the control is still not optimal.

<Tb>

Convert <SEP> 85%
<Tb>
<tb> Mnexp <SEP> 22 <SEP> 400 <SEP> g / mole
<Tb>
<tb> Mnthéo <SEP> 17 <SEP> 000 <SEP> g / mole
<Tb>
<tb> Mw / Mn <SEP> 1, <SEP> 7 <SEP>
<Tb>
<tb> f <SEP> 0.76
<Tb>

<Desc / Clms Page number 26>

Example 4
Controlled polymerization of MMA with a mixture of TTF and DEPN
4.7 g (5 ml) of MMA, 19.5 mg of AIBN, 120 mg of DEPN at 71% purity and 48 mg of TTF (molar ratio) are mixed in a Schlenk tube provided with magnetic stirring. DEPN / AIBN = 2.55 and TTF / AIBN molar ratio = 1.9) and the mixture is heated to the desired temperature of 90 ° C. The time at which the mixture reaches the temperature of 90 ° C. is defined as start time of the test. Samples are taken over time. This makes it possible to calculate the conversion to polymer obtained after evaporation under vacuum (0.01 mbar, 100 C, 30 min.) Of the monomer remaining in a sample. The Mnthéo at 100% conversion is 20,000 g / mole.

 The results are reported in Table 3.

TABLE 3

<tb> Time <SEP> Conversion <SEP> 1
<Tb>
<Tb>
<Tb>
<tb> (time) <SEP> (%) <SEP> ln (<SEP>)
<Tb>
<Tb>
<Tb>
<tb> 1-Conversion
<Tb>
<Tb>
<Tb>
<Tb>
<Tb>
<Tb>
<Tb>
<tb> 0 <SEP> 0 <SEP> 0
<Tb>
<Tb>
<Tb>
<Tb>
<Tb>
<Tb>
<Tb>
<Tb>
<Tb>
<tb> 5 <SEP> 35 <SEP> 0.43
<Tb>
<Tb>
<Tb>
<Tb>
<Tb>
<Tb>
<Tb>
<tb> 7 <SEP> 39 <SEP> 0.49
<Tb>
<Tb>
<Tb>
<Tb>
<Tb>
<Tb>
<Tb>
<Tb>
<tb> 10 <SEP> 43 <SEP> 0.56
<Tb>
<Tb>
<Tb>
<Tb>
<Tb>
<Tb>
<Tb>
<tb> 12 <SEP> 46 <SEP> 0.62
<Tb>
<Tb>
<Tb>
<Tb>
<Tb>
<Tb>
<Tb>
<Tb>
<tb> 14 <SEP> 55 <SEP> 0.80
<Tb>
<Tb>
<Tb>
<Tb>
<Tb>
<Tb>
<Tb>
<Tb>
<tb> 17 <SEP> 67 <SEP> 1,11
<Tb>
<Tb>
<Tb>
<Tb>
<Tb>
<Tb>
<Tb>
<tb> 19 <SEP> 71 <SEP> 1.24
<Tb>
<Tb>
<Tb>
<Tb>
<Tb>
<Tb>
<Tb>
<Tb>
<tb> 23 <SEP> 73 <SEP> 1.31
<Tb>
<Tb>
<Tb>
<Tb>
<Tb>
<Tb>
<Tb>
<tb> 33 <SEP> 90 <SEP> 2.30
<Tb>
The polymerization is well controlled.

<Desc / Clms Page number 27>

<Tb>

Convert <SEP> 90%
<Tb>
<tb> Mnexp <SEP> 18 <SEP> 800 <SEP> g / mole
<Tb>
<tb> Mnthéo <SEP> 18 <SEP> 000 <SEP> g / mole
<Tb>
<tb> Mw / Mn <SEP> 1.3
<Tb>
<tb> f <SEP> 0.96 <SEP>
<Tb>

ln(1/(1-conversion)) en fonction du temps (en heures) pour les Exemples respectivement 2 à 4. Examples 2, 3 and 4 can be summarized using the Summary Table 4 below and the single FIGURE of the accompanying drawing which shows the graphs

ln (1 / (1-conversion)) as a function of time (in hours) for Examples 2 to 4 respectively.

TABLE 4

<tb> Example <SEP> Curve <SEP> Factor <SEP> Mw / Mn
<Tb>

ln(1/(1-conversion)) f

ln (1 / (1-conversion)) f

<tb> vs <SEP> t
<Tb>
<Tb>
<Tb>
<Tb>
<tb> 1 <SEP> (not- <SEP> 0.86 <SEP> 2.2
<Tb>
<tb> additive)
<Tb>
<Tb>
<tb> (comparative)
<Tb>
<Tb>
<Tb>
<Tb>
<tb> 2 <SEP> (DEPN) <SEP> no <SEP> Linear
<Tb>
<Tb>
<tb> (comparative)
<Tb>
<Tb>
<Tb>
<Tb>
<tb> 3 <SEP> (TTF) <SEP> no <SEP> linear <SEP> 0.76 <SEP> 1.7
<Tb>
<Tb>
<tb> (comparative)
<Tb>
<Tb>
<Tb>
<Tb>
<tb> 4 <SEP> (DEPN <SEP> + <SEP> TTF) <SEP> Linear <SEP> 0.96 <SEP> 1.3
<Tb>
<Tb>
<tb> (according to
<Tb>
<Tb>
<tb> the invention)
<Tb>

It can be seen that associating the DEPN with the TTF improves the control of the polymerization of the MMA, which is also attested by the values of f and Mw / Mn. The factor f is increased and the polymolecularity is lowered, which is a sign of better control.

Claims (28)

1 - Process for the polymerization or copolymerization of at least one radically polymerizable monomer in the presence of at least one stable free radical and at least one electron donor, where appropriate in the presence of at least one an electron acceptor, the electron donor / electron acceptor (s) molar ratio being greater than 1.  2 - Process according to claim 1, characterized in that one selects the stable free radical or radicals among the nitroxide radicals.  3 - Process according to claim 2, characterized in that the nitroxide radicals are chosen from those of formulas (Ia), (Ib) or (Ic) (Ic):

 in which: # R1 to R3, R5 to R8 and R13 and R14 each independently represent: (a) a hydrogen atom; (b) a halogen atom; (c) a hydrocarbon group, saturated or unsaturated, linear, branched or mono- or polycyclic, and may be substituted by at least one halogen; <Desc / Clms Page number 29>  another heteroatom and / or at least one -C- group, and o may also comprise a fused ring, saturated or unsaturated; two of R1 to R3, R5 and R6, R7 and R8, R9 and R10, R11 and R12, R6 and R9, R8 and R11, R13 and R14 and - in the

 1 of N-O., Said heterocyclic ring being saturable or unsaturated, may comprise in the ring at least one

R1 to R3) R3 may be connected to R'3 - to form a heterocycle containing the nitrogen atom  wherein R17 and R18 each independently represent a linear, branched or cyclic alkyl, perfluoroalkyl, aryl, aralkyl, alkaryl, alkoxyl, aryloxyl, aralkyloxyl, alkaryloxyl radical, which radicals may comprise from 1 to 20 carbon atoms; or halogen; (f) a polymer chain; - R4 has the meanings defined in (a), (b), (c), (d) and (f) above, and in the case where it is connected to the nitrogen atom by an atom of carbon, the latter may carry at least one group as defined in point (e) above; R 9 to R 12, which are identical or different, have the meanings defined in points (a) to (f) above and may furthermore represent a hydroxide group or an acidic group, such as -COOH, -PO (OH) 2 or -SO3H; - R3 and R4 can be connected to each other, and - in the case where R4 represents a residue -CR'1R'2R'3 (R'1 to R'3 having indifferently the meanings of

 (d) an ester group -COOR15 or an alkoxyl group -OR16, R15 and R16 representing a hydrocarbon group as defined in (c) above; <Desc / Clms Page number 30>  where R4 represents a residue -CR'1R'2R'3, R3et R'3- independently connectable to form, with the carbon atom which carries them, a saturated or unsaturated ring or heterocycle; u is a non-zero integer.  4 - Process according to one of claims 2 and 3, characterized in that the nitroxide radicals

 RL comprises a sequence of formula -C-N-O 'wherein RL has a molar mass greater than 15.  5 - Process according to claim 4, characterized in that RL has a molar mass of 40 to 450.  6 - Process according to one of claims 3 to 5, characterized in that the nitroxide radicals of formula (Ia) in which R3 and R4 (or R3 and R) are connected to each other, among:

<Desc / Clms Page number 31> Ra to Rk and Rm independently have the meanings given for R9 to R12, Ra and Rb and Re and Rf may be the same or different when carried by different carbon atoms; r is 2 or 3 or 4; - s is a non-zero integer; and - t is 0, 1 or 2.  or :

 7 - Process according to one of claims 3 to 6, characterized in that one selects the stable radical (s) nitroxide among: # 2,2,5,5 tetramethyl-1-pyrrolidinyloxy; 3-carboxy-2,2,5,5-tetramethylpyrrolidinyloxy; 2,2,6,6-tetramethyl-1-piperidinyloxy; 4-hydroxy-2,2,6,6-tetramethyl-1-piperidinyloxy; 4-methoxy-2,2,6,6-tetramethyl-1-piperidinyloxy; 4-oxo-2,2,6,6-tetramethyl-1-piperidinyloxy; bis- (1-oxyl-2,2,6,6-tetramethylpiperidin-4-yl) sebacate; 2,2,6,6-tetramethyl-4-hydroxypiperidin-1-oxyl) monophosphonate; # N-tert-butyl-1-diethylphosphono-2,2-dimethylpropyl nitroxide; # N-tert-butyl-1-dibenzylphosphono-2,2-dimethylpropyl nitroxide; # N-tert-butyl-1-di (2,2,2-trifluoroethyl) phosphono- 2,2-dimethylpropyl nitroxide; <Desc / Clms Page number 32>  N- (1-methylethyl) -1-cyclohexyl-1- (diethylphosphono) nitroxide; N- (1-phenylbenzyl) - [(1-diethylphosphono) -1-methylethyl] nitroxide; # N-phenyl-1-diethylphosphono-2,2-dimethylpropyl nitroxide; # N-phenyl-1-diethylphosphono-1-methyl ethyl nitroxide; N- (1-phenyl-2-methylpropyl) -1-diethylphosphono-1-methylethyl nitroxide; # N-tert-butyl-1-phenyl-2-methylpropyl nitroxide; and # N-tert-butyl-1- (2-naphthyl) -2-methylpropyl nitroxide.

 # N-tert-butyl - [(1-diethylphosphono) -2-methylpropyl] nitroxide;  8 - Process according to claim 1, characterized in that 2,4,6-tri-tert.-butylphenoxy is used as a stable free radical.  9 - Process according to one of claims 1 to 8, characterized in that the electron donor (s) is chosen from among the compounds of the formulas:

<Desc / Clms Page number 33>

<Desc / Clms Page number 34>

<Desc / Clms Page number 35> C1-C5, -CF3, a halogen atom, -CN, -SR28, -OR28 or -NR29R30; # with R28 to R30 each representing C1-C25 alkyl or C6-C18 aryl; one of R29 and R30 may further represent a hydrogen atom; R31 - R26 represents a hydrogen atom, an alkyl residue in D represents -OH, -OR28, -SR28 or -NR29R30 or a C4-C7 cycloaliphatic residue which may be interrupted by at least one of -O-, -S- or -N-  where: A represents sulfur or selenium; - R20 to R23 each independently represent a hydrogen atom; C1-C20 alkyl, C1-C20 alkoxy or C6-C18 aryl; Y represents oxygen or sulfur; - R24 represents C1-C20 alkyl, C1-C20 alkoxy or C6-C18 aryl; n is an integer of 2 to 6; Z represents oxygen, sulfur or selenium; R 25 represents a hydrogen atom or a radical of formula: -B-D in which: B represents a linear or branched C1-C25 alkylene radical; <Desc / Clms Page number 36>  interrupted by at least one of -O-, -S- or -N-; R 131 # R31 representing a C1-C10 alkyl residue; R27 and R32 to R35 each independently represent a hydrogen atom; a C1-C20 alkyl residue or a C6-C18 aryl residue; m is 0 or is an integer of 1 to 4; q is 0, 1 or 2; p is an integer from 2 to 100.

 # R29 and R30 may form together with the nitrogen atom to which they are attached a C4-C7 cyclo-N-aliphatic ring, unsubstituted or substituted by at least one C1-C5 alkyl group, and which may be  10 - Process according to claim 9, characterized in that one uses, as electron donors, a compound of formula:

 or a compound of formula:

11 - Process according to one of claims 1 to 10, characterized in that the molar ratio -NO # / monomer or mixture of monomers is between 0.00001 and 1. <Desc / Clms Page number 37>  12- Process according to claim 11, characterized in that the molar ratio -NO '/ monomer or mixture of monomers is between 0.00005 and 0.5.  13 - Process according to one of claims 1 to 12, characterized in that the electron donor / monomer or monomer mixture molar ratio is between 0.00001 and 1.  14- The method of claim 13, characterized in that the electron donor / monomer or monomer mixture molar ratio is between 0.00005 and 0.5.  15 - Method according to one of claims 1 to 14, characterized in that the monomer or monomers involved are selected from vinyl monomers, allylic, vinylidene, diene and olefinic.  16- The method of claim 15, characterized in that the monomer or monomers involved are methacrylates.  17- Method according to claim 16, characterized in that the monomer involved is methyl methacrylate.  18 - Method according to one of claims 1 to 17, characterized in that it is conducted in the presence of at least one initiator of free radicals.  19- The method of claim 18, characterized in that the free radical initiator or initiators are introduced into the polymerization or copolymerization medium at a rate of 0.001 to 10% by weight relative to the monomer or the mixture of monomers.  20 - Method according to one of claims 18 and 19, characterized in that the molar ratio -NO # / initiator (s) of free radicals is between 0.1 and 10.  21- Method according to claim 20, characterized in that the molar ratio -NO * / initiator (s) of free radicals is between 0.5 and 5. <Desc / Clms Page number 38>  22 - Method according to one of claims 18 to 21, characterized in that the electron donor / (s) of free radicals molar ratio is between 0.1 and 10.  23 - Process according to claim 22, characterized in that the molar ratio donor (s) of electrons / initiator (s) of free radicals is between 0.5 and 5.  24 - Method according to one of claims 1 to 23, characterized in that it is conducted in the presence of at least one electron acceptor.  25- Method according to claim 24, characterized in that the electron donor / electron acceptor (s) molar ratio is greater than 2.  26 - Method according to one of claims 1 to 23, characterized in that it is conducted in the absence of an electron acceptor.  27 - Method according to one of claims 1 to 26, characterized in that the (co) polymerization is conducted at a temperature of 0 to 200 C.  28. A process according to claim 27, characterized in that the (co) polymerization is carried out at a temperature of 50 to 150 C.