METHOD FOR SYNTHESISING POLYMERS BY CONTROLLED-RADICAL INVERSE EMULSION POLYMERISATION

Abstract

The present invention relates to a method for preparing a polymer reverse emulsion polymerization comprising the following steps: a) Preparation of an aqueous phase comprising at least one water-soluble monomer and at least one water-soluble precursor of formula (I):

##STR00001## b) Preparation of an organic phase comprising a lipophilic solvent and at least one water-in-oil surfactant, c) Mixing the aqueous phase and the organic phase while stirring to form an inverse emulsion, d) Once the inverse emulsion has been formed, addition of a radical polymerization initiator in said inverse emulsion, and obtaining a polymer by polymerization of at least one water-soluble monomer.

Claims

1. A method for preparing a polymer by reverse emulsion polymerization comprising the following steps: a) preparing an aqueous phase comprising at least one water-soluble monomer and at least one water-soluble precursor of formula (I): ##STR00005## in which Z=O, S or N R.sup.1 and R.sup.2, being identical or different, represent: an optionally substituted alkyl, acyl, alkenyl or alkynyl group (i), or a carbon-based ring (ii), saturated or not, optionally substituted, or aromatic, or a heterocycle (iii), saturated or unsaturated, optionally substituted, or aromatic, which groups and rings (i), (ii) and (iii) may be substituted by substituted aromatic groups or alkoxycarbonyl or aryloxycarbonyl (—COOR), carboxy (—COOH), acyloxy (—O.sub.2CR)), carbamoyl (—CONR.sub.2), cyano (—CN), alkylcarbonyl, alkylarylcarbonyl, arylcarbonyl, arylalkylcarbonyl, phthalimido, maleimido, succinimido, amidino, guanidimo, hydroxy (—OH), amino (—NR.sub.2), halogen, allyl, epoxy, alkoxy (—OR), S-alkyl, S-aryl, groups having a hydrophilic or ionic character, such as alkali metal salts of carboxylic acids, alkali metal salts of sulfonic acid, polyalkylene oxide chains (POE, POP), cationic substituents (quaternary ammonium salts), R representing an alkyl or aryl group, A is a linear or structured polymer chain comprising n identical or different monomers, n is an integer between 1 and 500, b) preparing an organic phase comprising a lipophilic solvent and at least one water-in-oil surfactant, c) mixing the aqueous phase and the organic phase while stirring to form an inverse emulsion, and d) once the inverse emulsion has been formed, adding a radical polymerization initiator to said inverse emulsion, and obtaining a polymer by polymerizing the at least one water-soluble monomer.

2. The method according to claim 1, wherein Z=O.

3. The method according to claim 1, wherein: Z=O, A is a linear or structured polymer chain obtained from 1 to 100 monomers comprising at least one nonionic monomer and/or at least one anionic monomer and/or at least one cationic monomer.

4. The method according to claim 1, wherein: Z=O, A is a linear or structured polymer chain obtained from 1 to 100 monomers comprising at least one nonionic monomer and/or at least one anionic monomer and/or at least one associative cationic monomer.

5. The method according to claim 1, wherein: Z=O, A is a linear or structured polymer chain obtained from 1 to 100 monomers comprising at least one nonionic monomer and/or at least one anionic monomer and/or at least one monomer comprising an LCST group.

6. The method according to claim 1, wherein the aqueous phase comprises a water-soluble monomer/precursor ratio of between 12,500:1 and 300,000:1.

7. The method according to claim 1, wherein the precursor is of the formula (II): ##STR00006## where n is an integer between 1 and 100.

8. The method according to claim 1, wherein the water-soluble monomer is chosen from the group consisting of nonionic monomers; anionic monomers; and mixtures of nonionic monomers and anionic monomers.

9. The method according to claim 1, wherein the water-soluble monomer is a nonionic monomer chosen from the group consisting of acrylamide, methacrylamide, N-isopropylacrylamide, N, N-dimethylacrylamide; N, N diethylacrylamide; N-methylolacrylamide; N-vinylformamide; N-vinyl acetamide; N-vinylpyridine; N-vinylpyrrolidone; acryloyl morpholine (ACMO); glycidyl methacrylate; glyceryl methacrylate and diacetone acrylamide.

10. The method according to claim 1, wherein the water-soluble monomer is an anionic monomer chosen from the group consisting of acrylic acid; methacrylic acid; itaconic acid; crotonic acid; maleic acid; fumaric acid; 2-acrylamido 2-methylpropanesulfonic acid; vinylsulfonic acid; vinylphosphonic acid; allylsulfonic acid; allylphosphonic acid; styrene sulfonic acid; said anionic monomer being unsalified, partially or totally salified, and the salts of 3-sulfopropyl methacrylate.

11. The method according to claim 1, wherein the molecular weight of the polymer obtained is between 1,250,000 and 30,000,000 by weight.

12. The method according to claim 1, wherein the obtained polymer has a polydispersity less than or equal to 2.

13. The method according to claim 1, wherein n is an integer between 2 and 500.

14. The method according to claim 1, wherein R.sup.1 and R.sup.2 are identical or different and chosen from the group consisting of a linear or branched alkyl group comprising from 1 to 20 carbon atoms; a linear or branched acyl group comprising from 2 to 20 carbon atoms; a linear or branched alkenyl group comprising from 2 to 20 carbon atoms; a linear or branched alkynyl group comprising from 2 to 20 carbon atoms; and in that R represents a linear or branched alkyl group comprising from 1 to 20 carbon atoms, or aryl comprising from 6 to 10 carbon atoms.

15. The method according to claim 1, wherein n is an integer between 3 and 100.

16. The method according to claim 1, wherein the obtained polymer has a polydispersity less than or equal to 1.5.

17. The method according to claim 7, wherein the molecular weight of the polymer obtained is between 1,250,000 and 30,000,000 by weight.

18. The method according to claim 17, wherein the water-soluble monomer is: a nonionic monomer chosen from the group consisting of acrylamide, methacrylamide, N-isopropylacrylamide, N, N-dimethylacrylamide; N, N diethylacrylamide; N-methylolacrylamide; N-vinylformamide; N-vinyl acetamide; N-vinylpyridine; N-vinylpyrrolidone; acryloyl morpholine (ACMO); glycidyl methacrylate; glyceryl methacrylate and diacetone acrylamide; or an anionic monomer chosen from the group consisting of acrylic acid; methacrylic acid; itaconic acid; crotonic acid; maleic acid; fumaric acid; 2-acrylamido 2-methylpropanesulfonic acid; vinylsulfonic acid; vinylphosphonic acid; allylsulfonic acid; allylphosphonic acid; styrene sulfonic acid; said anionic monomer being unsalified, partially or totally salified, and the salts of 3-sulfopropyl methacrylate.

19. The method according to claim 18, wherein n is an integer between 4 and 50.

20. The method according to claim 1, wherein R.sup.1 and R.sup.2 are identical or different and chosen from the group consisting of a linear or branched alkyl group comprising from 1 to 10 carbon atoms; a linear or branched acyl group comprising from 2 to 10 carbon atoms; a linear or branched alkenyl group comprising from 2 to 10 carbon atoms; a linear or branched alkynyl group comprising from 2 to 10 carbon atoms; and in that R represents a linear or branched alkyl group comprising from 1 to 10 carbon atoms, or aryl comprising from 6 to 10 carbon atoms.

Description

FIGURES

[0086] FIG. 1 illustrates the reversible equilibrium between a dormant species and an active species in a process of radical polymerization by reversible deactivation.

[0087] FIG. 2 illustrates the proton nuclear magnetic resonance spectrum (.sup.1H NMR) of the water-soluble precursor of formula (I) of Example 1.

EXAMPLE EMBODIMENTS OF THE INVENTION

Example 1: Synthesis of the Water-Soluble Precursor

[0088] In a 50 kg reactor were introduced at room temperature (20° C.), 2 kg of O-ethyl-S-(1-methoxycarbonyl) ethyl dithiocarbonate, 10 kg of acrylamide, 12 kg of water, 20 kg of acetic acid and 140 g of azo initiator (V 044). The mixture was degassed by bubbling with nitrogen and then heated with stirring to 60° C. The polymerization reaction is carried out for 3 hours with stirring.

[0089] The water-soluble precursor thus obtained corresponds to formula (I) in which: [0090] Z=0, [0091] R.sup.1=CH.sub.2—CH.sub.3, [0092] A=(CH(C(═O)NH.sub.2)—CH.sub.2).sub.n [0093] n=7, [0094] R.sup.2=CH(CH.sub.3)—C(═O)—O—CH.sub.3.

[0095] This precursor has in particular been characterized by its 1H NMR spectrum (300.13 MHz) in D.sub.2O (FIG. 2).

Example 2: Synthesis of a Polymer P1 in Inverse Emulsion According to the Invention

[0096] Preparation of the aqueous phase: 400 g of acrylamide (50% by weight in water), 90 g of acrylic acid, 150 g of water and 0.0015% by weight with respect to the emulsion were mixed, of the water-soluble precursor of Example 1. The aqueous phase was neutralized with 90 g of sodium hydroxide (50% by weight in water).

[0097] Preparation of the organic phase: all the water-in-oil surfactants (an alkanolamide 2.5% by weight relative to the emulsion, and a stearyl methacrylate 3% by weight relative to the emulsion) were mixed in 200 g of ISOPAR type oil (Isopar N and L).

[0098] The aqueous phase and the organic phase were mixed and emulsified. The emulsion was then degassed for 60 minutes before the polymerization was initiated by adding a reducing agent, sodium metabisulfite (SMB).

[0099] At the end of the polymerization, the polymer obtained is recovered by precipitation in acetone.

Example 3: Synthesis of a P2 Polymer in Inverse Emulsion

[0100] The polymer P2 is synthesized as in Example 2, replacing the water-soluble precursor with sodium hypophosphite.

Example 4: Synthesis of an Inverse Emulsion Polymer P3

[0101] The polymer P3 is synthesized as in Example 2 by replacing the water-soluble precursor by the precursor corresponding to formula (I) in which Z=O, R.sup.1=CH.sub.2—CH.sub.3, R.sup.2=CH.sub.3 and A=CH—(CH.sub.3)C(═O)—O—, A is not in being in this case (and contrary to the invention) a monomer.

##STR00004##

Example 4: Characterization of Polymers P1, P2 and P3

[0102] The three polymers P1, P2 and P3 were analyzed by size exclusion chromatography (CES) under the following conditions: one Shodex SB807-G precolumn and two Shodex OHpak columns in series (SB-807 HQ and SB-805 HQ) coupled with a refractive index detector (Optilab T-rEX, Wyatt Technology, and Dawn Heleos II18 angles, Wyatt Technology).

TABLE-US-00001 TABLE 1 values of the molecular weights in number and in weight and the polydispersity index of P1, P2 and P3 Polymer Mn Mw Ip P1 2.10 10.sup.6 2.40 10.sup.6 1.14 P2 2.20 10.sup.6 >7.70 10.sup.6* 3.50 P3   >4 10.sup.6* >7.70 10.sup.6* >1.9* *the results obtained reach the separation limits of the method. Beyond a molecular weight Mw of 7.10.sup.6, it is no longer possible to separate the different molecular weights.

[0103] At number equivalent molecular weight, the polydispersity of the polymer in the presence of hydrophilic precursor is much lower than that of the polymer prepared by conventional radical polymerization.

[0104] The number molecular weight of the polymer P3 was difficult to control because the precursor used is not soluble in water, which is equivalent to polymerization without a precursor.