EP1951774A1

EP1951774A1 - Method for preparing a living polymer comprising methacrylic and/or methacrylate units

Info

Publication number: EP1951774A1
Application number: EP06842012A
Authority: EP
Inventors: Pierre Gerard; Stéphanie Magnet; Olivier Guerret; Julien Nicolas; Bernadette Charleux
Original assignee: Arkema France SA
Current assignee: Arkema France SA
Priority date: 2005-11-21
Filing date: 2006-11-20
Publication date: 2008-08-06
Also published as: JP5087552B2; JP2009516762A; WO2007057620A1; US20080306169A1; FR2893621A1; CN101360771A; US7935769B2; CN101360771B; FR2893621B1

Abstract

The invention relates to a method for preparing a living polymer comprising methacrylic and/or methacrylate units using a monofunctional or polyfunctional alkoxyamine consisting in polymerising one or several types of methacrylic and/or methacrylate monomers in the presence of at least one type of styrenic monomer.

Description

PROCESS FOR THE PREPARATION OF A LIVING POLYMER COMPRISING METHACRYLIC AND / OR METHACRYLATE UNITS

DESCRIPTION

TECHNICAL AREA

The present invention relates to a process for preparing a living polymer comprising methacrylic and / or methacrylate units.

The present invention also relates to a process for the preparation of a multiblock copolymer whose (s) blocks comprising methacrylic and / or methacrylate units present (s) a living character.

The general field of the invention is therefore that of controlled living radical polymerization.

The controlled radical polymerization makes it possible to reduce the deactivation reactions of the growing radical species, in particular the termination stage, reactions which, in conventional radical polymerization, interrupt the growth of the polymer chain irreversibly and without control.

In order to reduce the probability of termination reactions, it has been proposed to transiently and reversibly block the growing radical species, forming so-called "dormant" active species in the form of a low dissociation energy bond. This thus makes it possible to obtain polymer chains having a controlled average molecular mass (or mass) and a lower polymolecularity index than conventional radical polymerization. This also makes it possible to synthesize block copolymers by starting the synthesis of a block on the dormant species.

It is known in the prior art processes for obtaining living polymers based on acrylate units or multiblock copolymers comprising at least one block of acrylate units having a living character.

Thus, EP 1256138 describes the preparation of a triblock polymer B-A-B, wherein A represents a n-butyl polyacrylate block and B represents polymethyl methacrylate blocks, which process comprises successively the following steps:

a step of preparation of living difunctional block A by polymerization of n-butyl acrylate in the presence of a difunctional alkoxyamine acting as initiator and control agent;

a step of adding methyl methacrylate to the reaction medium comprising the synthesized block A, the polymerization being restarted at both ends of the block A because of the living character of this block.

The process described in this document has the following drawbacks:

the degree of conversion of methyl methacrylate in the B blocks is insufficient, insofar as it does not exceed 50%;

the BAB block copolymer obtained has a polymolecularity index of the order of 2, which is too high, showing a certain inhomogeneity in term of lengths of polymer chains constituting the mixture obtained;

it is not possible to reinitiate the synthesis of subsequent blocks from the B blocks, since the B blocks do not have a living character, which considerably limits the number of polymer architectures that can be envisaged with this process.

The inventors have set themselves the goal of setting up a method for obtaining a living polymer comprising methacrylic and / or methacrylate units allowing the rebooting of at least one of its ends and which allows:

when the living polymer based on methacrylic and / or methacrylate units is synthesized by reinitiating the polymerization from a block of a different nature, to obtain a degree of conversion of the methacrylic and / or methacrylate monomers constituting the 90% and this within a reasonable time of the order of a few hours of polymerization;

to obtain block copolymers comprising one or more living blocks based on methacrylic and / or methacrylate units having a polymolecularity index of less than 2.

The authors have discovered, surprisingly, that by adding, during the synthesis of the block comprising methacrylic and / or methacrylate units, styrene monomers to the reaction mixture, it is possible to give the resulting block a living character. I / INVENTION STATEMENT

Thus, the invention relates, according to a first object, to a process for the preparation of a living polymer comprising methacrylic and / or methacrylate units resulting from the polymerization of one or more methacrylic and / or methacrylate monomers using:

at least one monofunctional alkoxyamine of formula (I) below:

(D in which:

R 1 and R ₃ , which may be identical or different, represent a linear or branched alkyl group having a number of carbon atoms ranging from 1 to 3;

R ₂ representing a hydrogen atom, a linear or branched alkyl group having a number of carbon atoms ranging from 1 to 8, a phenyl group, an alkali metal such as Li, Na, K, an ammonium ion; such as NH ₄ ⁺ , NHBu ₃ ⁺ ; preferably R ₁ being CH ₃ and R ₂ being H; and or

at least one polyfunctional alkoxyamine of formula (III):

(III) wherein:

R 1, R 2 and R 3 are as defined above;

Z represents an aryl group or a group of formula Zi- [XC (O)] -, in which Zi represents a polyfunctional structure derived for example from a compound of the polyol type, X is an oxygen atom, an atom of nitrogen carrying a carbon group or a hydrogen atom, a sulfur atom; and - n is an integer greater than or equal to 2; said process for preparing the living polymer comprising a step of polymerizing the one or more methacrylic monomers and / or methacrylates in the presence of at least one styrenic monomer. It is specified that the symbol Et in the formulas above corresponds to the ethyl group.

In general, the styrene monomer (s) is (are) present in a content ranging from 2 to 90 mol% relative to the number of moles of methacrylic and / or methacrylate monomers. Preferably, the styrene monomer (s) is (are) present in a content lower than that of the methacrylic and / or methacrylate monomers, for example, in a content ranging from 4 to 9% by weight. moles relative to the number of moles of methacrylic monomers and / or methacrylates.

As examples of styrenic monomers, mention may be made of styrene, c-methylstyrene and styrenic derivatives substituted in the ortho, meta or para position.

By way of examples of methacrylic and / or methacrylate monomers, mention may be made of methacrylic acid, alkyl, cycloalkyl, alkenyl or aryl methacrylates, such as methyl methacrylate, lauryl or cyclohexyl, allyl or phenyl, hydroxyalkyl methacrylates such as 2-hydroxyethyl methacrylate or 2-hydroxypropyl methacrylate, ether alkyl methacrylates such as 2-ethoxyethyl methacrylate, alkoxy or aryloxy methacrylates polyalkylene glycol such as methoxypolyethylene glycol methacrylates, ethoxypolyethylene glycol methacrylates, methoxypolypropylene glycol methacrylates, methoxy-polyethyleneglycol-polypropylene glycol methacrylates or mixtures thereof, aminoalkyl methacrylates such as 2- (dimethylamino) ethyl methacrylate (MADAME ), amine salt methacrylates such as [2- (methacryloyloxy) ethyl] trimethyl chloride or sulfate thylammonium or chloride or sulphate, [2- (methacryloyloxy) - ethyl] dimethylbenzylammonium, fluorinated methacrylates such as 2, 2, 2-trifluoroethyl methacrylate, silylated methacrylates such as 3-methacryloylpropyltrimethylsilane, phosphorus methacrylates such as alkylene glycol phosphate methacrylates, hydroxyethylimidazolidone methacrylate , hydroxyethylimidazolidinone methacrylate, 2- (2-oxo-1-imidazolidinyl) ethyl methacrylate.

As an example of a monofunctional alkoxyamine that can be used, mention may be made of the one corresponding to the following formula:

The polyfunctional alkoxyamines of formula (III) are generally derived from a process consisting in reacting one or more alkoxyamines of formula (I) below:

(D in which R 1, R 2 and R 3 are as defined above, with at least one polyunsaturated compound of formula (II):

(II) wherein Z represents an aryl group or a group of formula Z ₁ - [XC (O) J _n , wherein Z ₁ represents a polyfunctional structure derived for example from a compound of the polyol type, X is an atom of oxygen, a nitrogen atom carrying a carbon group or a hydrogen atom, a sulfur atom and n is an integer greater than or equal to 2, in the presence or absence of solvent (s), preferably chosen from alcohols such as ethanol, aromatic solvents, chlorinated solvents, aprotic polar ethers and solvents, at a temperature ranging, in general, from 0 to 90 ^° C., preferably from 25 to 80 ° C. ⁰ C, the molar ratio between monofunctional alkoxyamine (s) of formula (I) and polyunsaturated compound (s) of formula (II) ranging from 1.5 to 1.5 n, preferably from at 1.25 n.

By way of examples of polyunsaturated compounds which can be used for producing polyfunctional alkoxyamines as defined above, mention may be made of polyfunctional vinylbenzenes (Z being then an aryl group) or of polyfunctional acrylic derivatives (Z being then a group of formula Zi [XC (O) J _n ) - Preferably, the polyunsaturated compound is divinylbenzene, trivinylbenzene, ethylene glycol diacrylate, 1,3-butanediol diacrylate, 1,4-butanediol diacrylate , 1,6-hexanediol diacrylate, neopentyl glycol diacrylate, cyclohexane dimethanol diacrylate, diethylene glycol diacrylate, triethylene glycol diacrylate, tetraethylene glycol diacrylate, dipropylene glycol diacrylate, tripropylene glycol diacrylate, polyethylene glycol diacrylates (marketed by Sartomer) under the names SR259, SR344, SR610), alkoxylated hexanediol diacrylates (sold by Sartomer under the names CD561, CD564, CD560), bisphenol-A diacrylate, ethoxylated bisphenol-A diacrylate (sold by Sartomer under the names SR 349, SR601, SR602, CD9038), trimethylolpropane triacrylate, pentaerythritol triacrylate, tris (2-hydroxyethyl) isocyanurate tri acrylate, ethoxylated trimethylolpropane triacrylate (sold by Sartomer under the names SR454, SR499, SR502, SR9035, SR415), propoxylated glyceryl triacrylate (sold by Sartomer under the name SR9020), propoxylated trimethylolpropane triacrylate (sold by Sartomer under the names SR492). and CD501), pentaerythritol tetraacrylate, di-trimethylolpropane tetracrylate, ethoxylated pentaerythritol tetraacrylate (sold by Sartomer under the name SR494), dipentaerythritol pentacrylate, modified caprolactones dipentaerythritol hexaacrylate (marketed by Sartomer under the names

Kayarad DCPA20 and DCPA60), dipentaerythritol polyacrylate (marketed by UCB Chemicals under the name DPHPA).

When Z corresponds to the formula Z ₁ - [X-C (O)] _n , the polyfunctional alkoxyamines have the following formula (HIa):

(HIa) Z ₁ generally corresponding to an alkylene group.

A particular example of a polyfunctional alkoxyamine according to the general definition given above is the polyfunctional alkoxyamine having the following formula:

this polyfunctional alkoxyamine being derived from the reaction of a monofunctional alkoxyamine of formula (I) with 1,4-butanediol diacrylate. Without the plaintiff being held to any explanation, she thinks that, in the case where the polymerization proceeds in emulsion, the monofunctional alkoxyamines of formula (I) and / or the polyfunctional alkoxyamines of formula (III) play both the role of initiator agent (and control agent) and emulsifying agent; thus, the surfactant properties of the water-soluble monofunctional alkoxyamines of formula (I) and / or polyfunctional alkoxyamines of formula (III) make it possible to moderate or even to avoid the use of other surfactants.

In particular, the monofunctional alkoxyamines of formula (I) and / or the polyfunctional alkoxyamines of formula (III) are water-soluble, when R2 is an alkali metal such as Li, Na, K or an ammonium ion such as NH ₄ ⁺ , NHBu ₃ ⁺ , Bu representing a butyl group. By water-soluble monofunctional alkoxyamine or water-soluble polyfunctional alkoxyamine for the purpose of the present invention is meant any monofunctional alkoxyamine of formula (I) or polyfunctional alkoxyamine of formula (III) whose solubility in water phase or (water / water-miscible compound) is at least 1 g / l at 25 ^° C.

The monofunctional alkoxyamine or polyfunctional alkoxyamine may be introduced into the polymerization medium in a proportion of 0.01% to 10%, preferably 0.1 to 5% by weight relative to the weight of monomer (s).

The process for preparing the living polymer according to the invention can be carried out by solvent, in bulk, in dispersed media (such as the emulsion, the suspension). The emulsion may be a miniemulsion or a microemulsion.

When the polymerization is carried out in emulsion, at least one emulsifying agent, that is to say a surfactant for stabilizing the emulsion, may be added to the polymerization medium, it being understood that the said emulsifying agent is not an alkoxyamine such as as defined above. Any emulsifying agent usual to this kind of emulsion can be used.

The emulsifying agent may be anionic, cationic or nonionic. The emulsifying agent may be an amphoteric or quaternary or fluorinated surfactant. It may be chosen from alkyl or aryl sulphates, alkyl or aryl sulphonates, fatty acid salts, polyvinyl alcohols, alcohols polyethoxylated fats. By way of example, the emulsifying agent can be chosen from the following list:

sodium lauryl sulphate,

sodium dodecylbenzenesulphonate, sodium stearate,

- nonylphenolpolyethoxylated,

sodium dihexylsulfosuccinate,

sodium dioctylsulfosuccinate,

lauryl dimethyl ammonium bromide, lauryl amido betaine,

perfluoro octyl potassium acetate.

The emulsifying agent may also be an amphiphilic block or random or graft copolymer, such as copolymers of sodium styrene sulphonate and in particular sodium polystyrene-b-poly (sodium styrene sulphonate) or any amphiphilic copolymer prepared by any other polymerization.

The emulsifying agent may be introduced into the polymerization medium in a proportion of 0.1% to 10% by weight relative to the mass of monomer (s).

A living polymer obtainable by the process of the invention is a polymethyl methacrylate comprising styrene units in a content ranging from 4 to 9 mol% relative to the number of moles of methyl methacryl units.

The process of the invention is a controlled and living radical process, insofar as it has been found that: the number-average molecular mass

(Mn) depending on the conversion of the monomers to polymers evolves linearly and that the natural logarithm of the ratio (Mo / M) (Mo representing the initial concentration of monomer (s) and M representing the monomer concentration at a given instant of the polymerization) evolves linearly as a function of time ;

- It is possible to reboot all the polymer chains obtained by this method by adding a monomer to make a grafted block obtained living polymer.

In addition, the process has the particular feature of allowing to obtain an excellent conversion rate of methacrylic monomers and / or methacrylates, this being of the order of 90%, whereas it was close to that in the prior art. 50% in the absence of styrenic monomers.

It is thus possible to prepare, using the process of the invention, polymers with a very high molecular weight and having a polymolecularity index of less than 2.

Thus, according to a second object, the invention relates to a living polymer comprising methacrylic and / or methacrylate units resulting from the polymerization of one or more methacrylic and / or methacrylate monomers obtainable by a process such as defined above.

It is therefore quite natural that the process of the invention mentioned above applies to the preparation of block copolymers. Thus, the invention relates, according to a third object, to a process for the preparation of a block copolymer comprising at least one block comprising methacrylic and / or methacrylate units resulting from the polymerization of methacrylic and / or methacrylate monomers, referred to as block B, in which said one or more B blocks are prepared by carrying out the process for preparing the living polymer as defined above, the living polymer thus being integrated in a copolymer in the form of a block.

Because of the living nature of this block, one can thus access a very large number of block copolymer architectures, according to the order of introduction of the constituent monomers of each of the blocks and the nature of the initiator and agent used (depending on whether it is a monofunctional alkoxyamine or a polyfunctional alkoxyamine).

In the rest of this presentation, we will consider that:

B represents a block resulting from the polymerization of methacrylic monomer (s) and / or methacrylate (s) and of styrene monomer (s) (B corresponding to the living polymer obtained according to the process described above);

A and C represent blocks resulting from the polymerization of monomers other than those of block B, these monomers possibly being acrylic monomers, acrylates, methacrylics, methacrylates optionally carrying acid groups, anhydride, hydroxyl, amine, poly (ethylene glycol), poly (ethylene oxide), styrenics and mixtures thereof.

Thus, it is possible to obtain, in accordance with the invention, copolymers comprising at least one block B and at least one block A, linked together by a covalent bond, by a process comprising successively: a) a step of setting contacting the constituent monomers of the block B with a monofunctional alkoxyamine or polyfunctional alkoxyamine as defined above for a sufficient time until completion of the polymerization reaction; b) a step of adding the monomers constituting the block A. Between steps a) and b), it can be provided a step of removing residual monomers unreacted in step a).

Due to the living character of the B block, the addition of the constituent monomers of the block A generates a polymerization of these monomers from one or both or more ends of the block B, depending on whether the initiator used is a monofunctional alkoxyamine or a polyfunctional alkoxyamine.

At the end of steps a) and b), the copolymer obtained comprises:

a sequence B-A, if the initiator used is a monofunctional alkoxyamine; or

a sequence B- (A) _n , if the initiator is a polyfunctional alkoxyamine, n corresponding to the same definition as that given above. For example, if n = 2, the copolymer obtained comprises an ABA sequence.

For example, if n = 3, the copolymer obtained comprises a sequence:

A B A

It is thus possible to access star and hyperbranched copolymers.

By way of example, A may be a block resulting from the polymerization of an alkyl methacrylate or methacrylic monomer and of another monomer chosen from acrylate monomers, styrene monomers and acrylates and methacrylates monomers which may carry groups. acid, anhydride, hydroxyl, amine, poly (ethylene glycol), poly (ethylene oxide), styrenic monomers and mixtures thereof.

It is also possible, in accordance with the invention, to obtain copolymers comprising at least one block A and at least one block B, connected to one another by a covalent bond, by a process comprising successively: a) a step of bringing the constituent monomers of block A with a monofunctional alkoxyamine or polyfunctional alkoxyamine as defined above for a time sufficient until completion of the polymerization reaction; b) a step of adding the constituent monomers of block B. Between steps a) and b) there may be provided a step of removing unreacted residual monomers in step a).

At the end of steps a) and b), the copolymer obtained comprises:

a sequence A-B, if the initiator used is a monofunctional alkoxyamine; or

a sequence A- (B) _n , if the initiator is a polyfunctional alkoxyamine, n corresponding to the same definition as that given above.

For example, if n = 2, the copolymer obtained comprises a sequence B-A-B. An example of copolymer B-A-B is a copolymer (methyl methacrylate, styrene / n-butyl acrylate / methyl methacrylate, styrene) obtained by a process as defined above, in which:

the constituent monomers of the block B are a mixture of methyl methacrylate and styrene, the styrene being present in a content ranging from 4 to 9 mol% relative to the number of moles of methyl methacrylate;

the constituent monomers of block A are n-butyl acrylate;

the alkoxyamine used in the process is a polyfunctional alkoxyamine corresponding to the following formula:

For example, if n = 3, the copolymer obtained comprises a sequence:

B A B

B

Because of the living character of the block B by the method of the invention, it may be envisaged at the end of step b) to add another monomer to form a copolymer comprising a triblock sequence A-B-C. Examples of triblock copolymers may be copolymers, in which:

- A is an acrylate or acrylic block;

B is a methacrylate and / or methacrylic and styrenic block according to the invention; - C is a block resulting from the polymerization of all types of vinyl monomers.

Such ABC copolymers can play a role in compatibilizing matrices of different nature, and this thanks to the presence of external blocks (A and C) of different chemical nature, while acting as a shock additive if the central block B present an elastomeric character. As mentioned above, the process for preparing block copolymers of the invention makes it possible to obtain copolymers:

comprising living blocks, in particular blocks based on methacrylic units and / or methacrylates, which was not conceivable in the processes of the prior art; and

having a polymolecularity index of less than 2, which makes it possible to obtain products with improved rheology that can be intended for applications such as lubricants, rheology modifiers for paints, paints, dispersants;

having higher molecular weights than the copolymers obtained with the processes of the prior art, because of a conversion rate of the order of 90% for the monomers constituting the B block (methacrylic monomers and / or methacrylates and styrenic monomers), which can make these copolymers interesting as additives for thermoplastics, such as polyvinyl chloride, especially for the conversion thereof.

Thus, according to a fourth object, the invention relates to block copolymers that can be obtained by a process as defined above. These copolymers as well as the living polymers defined above can be used in the constitution of numerous compositions such as:

- Cosmetic compositions comprising, besides said copolymers and / or living polymers, a physiologically acceptable medium; adhesive compositions, said compositions possibly comprising, in addition, additives such as tackifying resins, plasticizers, such as oils, in which case it will constitute a hot-melt pressure-sensitive adhesive composition (known by the abbreviation HMPSA);

thermoplastic compositions, which may furthermore comprise one or more thermoplastic polymers, such as polymethyl methacrylate, polystyrene and polyvinyl chloride;

- paint compositions. The invention will now be described using the examples below given for illustrative and non-limiting. DETAILED PRESENTATION OF PARTICULAR EMBODIMENTS

EXAMPLE 1

This example 1 illustrates the preparation of a difunctional alkoxyamine used as initiator and control agent for carrying out the process of the invention.

The preparation of the difunctional alkoxyamine proceeds in two steps:

the synthesis of a monofunctional alkoxyamine: 2-methyl-2- [N-tert-butyl-N- (1-diethoxyphosphoryl-2,2-dimethylpropyl) aminoxy] propionic acid corresponding to the following formula (step a):

the reaction of the monofunctional alkoxyamine with 1,4-butanediol diacrylate (step b) to obtain the difunctional alkoxyamine of the following formula:

1) Step a

In a nitrogen-purged 2 liter glass reactor, 500 ml of degassed toluene, 35.9 g of CuBr (250 mmol), 15.9 g of copper powder (250 mmol), 86.7 g are introduced. of N, N, N ', N', N "-pentamethyl-diethylenetriamine-PMDETA- (500 mmol), then, with stirring and at room temperature (20 ^° C.), a mixture containing 500 ml of degassed toluene is introduced, 42 1 g of 2-bromo-2-methylpropionic acid (250 mmol) and 78.9 g of nitroxide of formula:

84% or 225 mmol.

Allowed to react for 90 min at room temperature and with stirring, and the reaction medium is filtered. The toluene filtrate is washed twice with 1.5 liters of a saturated aqueous solution of NH ₄ Cl.

A yellowish solid is obtained which is washed with pentane to give 51 g of 2-methyl-2- [N-tert-butyl-N- (diethoxyphosphoryl-2,2-dimethylpropyl) aminoxy] propionic acid (60% yield). The analytical results are given below: molar mass determined by mass spectrometry: 381.44 / g. mol ^"1 (for C ₇ H ₃₆ NO ₆ P) elemental analysis (crude formula: C ₁₇ H ₃₆ NO ₆ P):

% calculated: C = 53.53, H = 9.51, N = 3.67% found: C = 53.57, H = 9.28, N = 3.77 melting on Bϋchi B-540 apparatus: 124 ⁰ C / 125 ⁰ C

2) Step b

In a 100 ml flask purged with nitrogen, the following are introduced:

2 g of alkoxyamine prepared in step a (2.1 equivalents);

0.55 g of 1,4-butanediol diacrylate marketed by Aldrich of 90% purity (1 equivalent);

- 5.7 mL of ethanol. It is refluxed (temperature 78 ^° C.) for 20 hours, then the ethanol is evaporated in vacuo. 2.5 of a very viscous yellow oil are obtained.

³¹ P NMR analysis shows the complete disappearance of the monofunctional alkoxyamine prepared in step a (27.4 ppm) and the appearance of dialkoxyamine (multiplet at 24.7-25.1 ppm).

The electrospray mass spectrometry analysis shows the mass 961 (M +).

EXAMPLE 2

This example illustrates a poly (n-butyl acrylate) polymer intended to constitute one of the blocks of a copolymer prepared according to the process of the invention.

To do this, in a polymerization reactor equipped with a variable speed stirring motor, inputs for the introduction of reagents, taps for the introduction of inert gases for the removal of oxygen, probes for measurement of the temperature, of a vapor condensation system with reflux, a double jacket for heating / cooling the reactor contents by circulating a coolant therein, is introduced:

320 g of n-butyl acrylate (ie 2.5 mol); and

8.8 g of polyfunctional alkoxyamine prepared according to the example mentioned above (ie 9.1 mmol). After several degassings with nitrogen, the reaction medium is brought to 115 ^° C. and this temperature is maintained by thermal regulation for several hours. Samples are taken throughout the reaction in order to:

- determine the kinetics of gravimetric polymerization (measurement of dry extract);

- follow the evolution of the number average molecular weight (Mn) as a function of the conversion of monomer to polymer.

When the 80% conversion is reached, the reaction medium is cooled to 60 ^° C. and the residual n-butyl acrylate is removed by evaporation under vacuum. The molecular weights of poly (n-butyl acrylate) in polystyrene equivalents determined by steric exclusion chromatography are 29690 g / mol for the mass at the peak of the distribution (Mp), 23 300 g / mol for the molecular weight number average (Mn) and 29 780 g / mol for the weight average molecular weight (Mw). The polymolecularity index is 1.3.

EXAMPLE 3 This example illustrates the reinforcement of the poly (n-butyl acrylate) prepared in Example 2 with methyl methacrylate.

At 60 ^° C., 391 g of methyl methacrylate

(3.9 moles) and 156 g of toluene are added to the difunctional poly (n-butyl acrylate) prepared according to Example 2. The reaction medium is then heated to 95 ⁰ C for 2 hours. The conversion achieved is of the order of 50%. After returning to ambient temperature, the copolymer solution (methyl methacrylate-b-n-butyl acrylate-b-methyl methacrylate) is withdrawn from the reactor and the residual monomers and solvents are removed by evaporation under vacuum.

The molecular weights of the copolymer (methyl methacrylate-b-n-butyl acrylate-b-methyl methacrylate) as polymethyl methacrylate equivalent by steric exclusion chromatography (known by the abbreviation SEC) are 98 910 g / mol for the mass at the peak of the distribution (Mp), 62 110 g / mol for the number average molecular weight (Mn) and 124 500 g / mol for the weight average molecular weight (Mw). The polymolecularity index is 2.0. The polymethyl methacrylate endblocks do not exhibit a living character. It is therefore not possible to reboot these blocks to carry out the synthesis of subsequent blocks.

EXAMPLE 4

This example illustrates the reinitiation of the poly (n-butyl acrylate) prepared in Example 2 to achieve the synthesis of end blocks based on methyl methacrylate, which end blocks are made in accordance with the principles of the present invention. .

At 60 ^° C., 391 g of methyl methacrylate (3.7 moles) and 17.7 g of styrene (0.17 moles) and 156 g of toluene are added to the poly (n-acrylate). butyl) difunctional prepared according to Example 2. The reaction medium is then heated at 95 ^° C. After 150 minutes, the conversion reaches about 90%. After returning to ambient temperature, the copolymer solution (methyl methacrylate, styrene-b-n-butyl acrylate-b-methyl methacrylate, styrene) is withdrawn from the reactor and the residual monomers and solvents are removed by evaporation under vacuum. .

The molecular weights of the copolymer (methyl methacrylate, styrene-n-butyl acrylate-methyl methacrylate, styrene) as polymethyl methacrylate equivalent determined by steric exclusion chromatography are 92300 g / mol for the number-average molecular weight ( Mn) and 129 220 g / mol for the weight average molecular weight (Mw). The polymolecularity index is 1.4.

EXAMPLE 5

This example illustrates the reinitiation of the poly (n-butyl acrylate) prepared in Example 2 to achieve the synthesis of end blocks based on methyl methacrylate, which end blocks are made in accordance with the principles of the present invention. . At 60 ^° C., 391 g of methyl methacrylate

(3.7 moles) and 17.7 g of styrene (0.17 moles) and 156 g of toluene are added to the difunctional poly (n-butyl acrylate) prepared according to Example 2. The reaction medium is then heated to 95 ⁰ C. After 150 minutes, the conversion reaches about 90%. After returning to ambient temperature, the solution of The copolymer (methyl methacrylate, styrene-b-n-butyl acrylate-b-methyl methacrylate, styrene) is withdrawn from the reactor and the residual monomers and solvents are removed by evaporation in vacuo. The molecular masses of the copolymer

(methyl methacrylate, styrene-n-butyl acrylate-methyl methacrylate, styrene) as polymethyl methacrylate equivalent determined by size exclusion chromatography are 92,300 g / mol for the number-average molecular weight (Mn) and 129 220 g / mol for the weight average molecular weight (Mw). The polymolecularity index is 1.4.

EXAMPLE 6

This example illustrates the reinitiation of the poly (n-butyl acrylate) prepared in Example 1 to achieve the synthesis of methacrylic acid end blocks, which end blocks are made in accordance with the present invention.

At 60 ^° C., 318 g of methacrylic acid (3.7 moles) and 17.7 g of styrene (0.17 moles) and 1340 g of 1,4-dioxane are added to the poly (n-butyl acrylate). difunctional prepared according to Example 1. The reaction medium is then heated to 90 ^° C. After 100 minutes, the conversion reaches about 80%. After returning to ambient temperature, the copolymer solution (methacrylic acid, styrene-n-butyl-b-acrylate, methacrylic acid, styrene) is withdrawn from the reactor and the residual monomers and solvents are removed by evaporation under vacuum.

Claims

Process for the preparation of a living polymer comprising methacrylic and / or methacrylate units resulting from the polymerization of one or more methacrylic and / or methacrylate monomers using:

at least one monofunctional alkoxyamine of formula (I) below:

(D in which:

R ₂ representing a hydrogen atom, a linear or branched alkyl group having a number of carbon atoms ranging from 1 to 8, a phenyl group, an alkali metal or an ammonium ion; or

at least one polyfunctional alkoxyamine of formula (III):

(III)

in which :

R 1, R 2 and R 3 are as defined above; Z represents an aryl group or a group of formula Zi- [XC (O)] -, in which Zi represents a polyfunctional structure, X is an oxygen atom, a nitrogen atom carrying a carbon group or a hydrogen atom, a sulfur atom; and -n is an integer greater than or equal to 2; said process for preparing the living polymer comprising a step of polymerizing the one or more methacrylic monomers and / or methacrylates in the presence of at least one styrenic monomer.

2. Process according to claim 1, in which the styrene monomer (s) is (are) present in a content ranging from 4 to 9 mol% relative to the number of moles of methacrylic monomers. and / or methacrylates.

3. Process according to claim 1 or 2, in which the methacrylate monomer (s) is (are) chosen from a group consisting of alkyl methacrylates, cycloalkyl methacrylates and methacrylates. alkenyl, aryl methacrylates, hydroxyalkyl methacrylates, alkyl ether methacrylates, alkoxy- or aryloxy-polyalkylene glycol methacrylates, aminoalkyl methacrylates, amino salt methacrylates, fluorinated methacrylates , silylated methacrylates, phosphorus methacrylates, hydroxyethylimidazolidone methacrylate, hydroxyethylimidazolidinone methacrylate, 2- (2-oxo-1-imidazolidinyl) ethyl methacrylate.

4. A process according to any one of the preceding claims, wherein the monofunctional alkoxyamine has the following formula:

The process according to any one of claims 1 to 3, wherein the polyfunctional alkoxyamine has the following formula:

6. A process according to any one of claims 1 to 5, wherein the monofunctional alkoxyamine or polyfunctional alkoxyamine is present in a content ranging from 0.01% to 10% by weight based on the total weight of monomers.

7. A process according to any one of the preceding claims, wherein the living polymer is a polymethyl methacrylate comprising styrene units in a content ranging from 4 to 9 mol% relative to the number of moles of methyl methacryl units.

8. A living polymer comprising methacrylic and / or methacrylate units resulting from the polymerization of one or more methacrylic and / or methacrylate monomers obtainable by a process as defined according to any one of claims 1 to 7.

9. Process for the preparation of a block copolymer comprising at least one block comprising methacrylic and / or methacrylate units resulting from the polymerization of methacrylic and / or methacrylate monomers, called block B, in which the said B block or blocks are prepared by the implementation of the process for preparing the living polymer as defined in any one of claims 1 to 7.

10. The method of claim 9, wherein the prepared copolymer comprises at least one block B and at least one block A, connected to each other by a covalent bond, which process comprises successively: a) a step of contacting the constituent monomers block A with a monofunctional alkoxyamine or polyfunctional alkoxyamine as defined in claim 1 for a time sufficient until completion of the polymerization reaction; b) a step of adding the constituent monomers of block B.

11. The process according to claim 10, wherein the polyfunctional alkoxyamine has the formula given in claim 5, the constituent monomers of the block B are a mixture of methyl methacrylate and styrene, the styrene being present in a content ranging from 4 to 9 mol% relative to the number of moles of methyl methacrylate and the monomers constituting block A are the n-acrylate; butyl, whereby a block copolymer (methyl methacrylate, styrene / n-butyl acrylate / methyl methacrylate, styrene) is obtained.

12. Block copolymer obtainable by a process as defined in any one of claims 9 to 11.

13. Cosmetic composition comprising in a physiologically acceptable medium at least one living polymer as defined in claim 8 and / or at least one copolymer as defined in claim 12.

14. Adhesive composition comprising at least one living polymer as defined in claim 8 and / or a copolymer as defined in claim 12.

15. Thermoplastic composition comprising at least one living polymer as defined in claim 8 and / or a copolymer as defined in claim 12.

16. A paint composition comprising at least one living polymer as defined in claim 8 and / or a copolymer as defined in claim 12.