Controlled radical polymerization in water-in-water dispersion

Abstract

The present invention relates to a method for preparing an aqueous dispersion of water-soluble polymers, which comprises a step (E) of radical polymerization, wherein the following are brought into contact in an aqueous medium (M) in which the synthesised polymer is not soluble: at least one ethylenically unsaturated monomer which is soluble in the aqueous medium (M); at least one source of free radicals; and a reactive stabiliser which comprises: a polymer chain (CP) which is soluble in the medium (M), a group (G) providing the radical polymerization of step (E) with a living and controlled nature, such as, for example, a group carrying a thiocarbonylthio —S(C═S)— group.

Claims

1. A process for preparing an aqueous dispersion of water-soluble polymer, which comprises a step (E) of radical polymerization to synthesize the water-soluble polymer, wherein the following are brought into contact in an aqueous medium (M) in which the synthesized water-soluble polymer is not soluble: at least one ethylenically unsaturated monomer which is soluble in the aqueous medium (M); at least one source of free radicals; and a reactive stabilizer which comprises: a polymer chain (PC) which is soluble in the medium (M), a group (G) providing the radical polymerization of step (E) with a living and controlled nature, wherein the step (E) of radical polymerization comprises polymerizing the at least one ethylenically unsaturated monomer in the presence of polymer chain (PC) to form the synthesized water-soluble polymer, wherein the synthesized water-soluble polymer comprises the polymer chain (PC) and the polymerized at least one ethylenically unsaturated monomer and has a molecular weight (M.sub.w) ranging from 20,000 to 5,000,000 g/mol and wherein the aqueous medium (M) comprises at least one salt which renders the synthesized polymer insoluble or improves said rendering.

2. The process as claimed in claim 1, wherein the group (G) is a group carrying a thiocarbonylthio —S(C═S)— group.

3. The process as claimed in claim 1, wherein step (E) is carried out with the presence of additional nonreactive stabilizing agents.

4. The process as claimed in claim 1, wherein step (E) is not carried out in the presence of additional nonreactive stabilizing agents.

5. The process as claimed in claim 1, wherein the group (G) present on the reactive stabilizer corresponds to the formula —S(C═S)—Z wherein Z represents: a hydrogen atom, a chlorine atom, an optionally substituted alkyl or optionally substituted aryl radical, an optionally substituted heterocycle, an optionally substituted alkylthio radical, an optionally substituted arylthio radical, an optionally substituted alkoxy radical, an optionally substituted acyloxy radical, an optionally substituted amino radical, an optionally substituted hydrazine radical, an optionally substituted alkoxycarbonyl radical, an optionally substituted aryloxycarbonyl radical, an optionally substituted carboxyl, acyloxy radical, an optionally substituted aroyloxy radical, an optionally substituted carbamoyl radical, a cyano radical, a dialkyl- or diaryl-phosphonato radical, a dialkyl-phosphinato or diaryl-phosphinato radical, or a polymer chain.

6. The process as claimed in claim 1, wherein the group (G) is a xanthate or a dithiocarbamate.

7. The process as claimed in claim 1, wherein the monomers used in step (E) are monomers which are soluble in the medium (M) and which are selected from the group consisting of: ethylenically unsaturated monocarboxylic and dicarboxylic acids, unsaturated carboxylic acid amides, vinylamine amides, α, β monoethylenically unsaturated amino esters, vinylpyridines, vinylamine, vinylimidazolines, monomers which are precursors of amine functions, which generate primary amine functions by simple acid or basic hydrolysis, ammoniumacryloyl or acryloyloxy monomers, trimethylammoniumpropylmethacrylate salts, trimethylammoniumethylacrylamide or -methacrylamide chloride or bromide, trimethylammoniumbutylacrylamide or -methacrylamide methylsulfate, trimethylammoniumpropylmethacrylamide methylsulfate (MAPTA MeS), (3-methacrylamidopropyl)trimethylammonium chloride (MAPTAC), (3-acrylamidopropyl)trimethylammonium chloride or methylsulfate (APTAC or APTA MeS), methacryloyloxyethyltrimethylammonium chloride or methylsulfate, acryloyloxyethyltrimethylammonium (ADAMQUAT) salts, such-as methyldiethylammoniumethyl acrylate methylsulfate (ADAEQUAT MeS), benzyldimethylammoniumethyle acrylate chloride or methylsulfate (ADAMQUAT BZ 80), 1-ethyl 2-vinylpyridinium bromide, chloride or methylsulfate, 1-ethyl 4-vinylpyridinium bromide, chloride or methylsulfate, N,N-dialkyldialllylamine monomers, dimethylaminopropylmethacrylamide,N-(3-chloro-2-hydroxypropyl)trimethylammonium chloride (DIQUAT chloride), dimethylaminopropylmethacrylamide,N-(3-methylsulfate-2-hydroxypropyl)trimethylammonium methylsulfate (DIQUAT methylsulfate), the monomer of formula ##STR00004## where X is an anion, and mixtures of two or more of these monomers.

8. The process as claimed in claim 1, wherein water-soluble crosslinking monomers are added together with or after the introduction of the water-soluble monomers.

9. The process as claimed in claim 1, wherein the medium (M) of step (E) also comprises at least one solvent which is water-soluble.

10. The process as claimed in claim 7, wherein said ethylenically unsaturated monocarboxylic and dicarboxylic acids is acrylic acid, methacrylic acid, itaconic acid, maleic acid or fumaric acid, said unsaturated carboxylic acid amides is acrylamide, methacrylamide, N-methylolacrylamide or -methacrylamide, N-alkylacrylamides, N,N-dimethylaminomethylacrylamide or -methacrylamide, 2-(N,N-dimethylamino)ethylacrylamide or -methacrylamide, 3-(N,N-dimethylamino)propylacrylamide or -methacrylamide, or 4-(N,N-dimethylamino)butylacrylamide or -methacrylamide, said vinylamine amides is vinylformamide, vinylacetamide, N-vinylpyrrolidone and N-vinylcaprolactam, said α,β monoethylenically unsaturated amino esters is 2-(dimethylamino)ethyl acrylate (ADAM), 2-(dimethylamino)ethyl methacrylate (DMAM or MADAM), 3-(dimethylamino)propyl methacrylate, 2-(tert-butylamino)ethyl methacrylate, 2-(dipentylamino)ethylmethacrylate, or 2-(diethylamino)ethyl methacrylate, said monomers which are precursors of amine functions is N-vinylformamide or N-vinylacetamide, said trimethylammoniumpropylmethacrylate salts is chloride, said acryloyloxyethyltrimethylammonium (ADAMQUAT) salts is acryloyloxyethyltrimethylammonium chloride or acryloyloxyethyltrimethylammonium methylsulfate (ADAMQUAT Cl or ADAMQUAT MeS), said N,N-dialkyldiallylamine monomers is N,N-dimethyldiallylammonium chloride (DADMAC).

11. The process according to claim 1, wherein the at least one salt which renders the synthesized polymer insoluble or improves said rendering is selected from the group consisting of organic and inorganic salts.

12. The process according to claim 11, wherein the at least one salt which renders the synthesized polymer insoluble or improves said rendering comprises at least one anion selected from the group consisting of sulfate, dihydrogenphosphate, phosphate and halide.

13. The process according to claim 12, wherein the at least one salt which renders the synthesized polymer insoluble or improves said rendering comprises at least one anion selected from the group consisting of sulfate, dihydrogenphosphate, and phosphate.

14. The process according to claim 1, wherein the at least one salt which renders the synthesized polymer insoluble or improves said rendering comprises at least one cation selected from the group consisting of sodium, potassium, calcium, magnesium, aluminum, zinc and ammonium cations, and mixtures thereof.

15. The process according to claim 14, wherein the at least one salt which renders the synthesized polymer insoluble or improves said rendering comprises at least one cation selected from the group consisting of sodium, potassium, calcium, aluminum, zinc and ammonium cations, and mixtures thereof.

16. The process according to claim 1, wherein the at least one salt which renders the synthesized polymer insoluble or improves said rendering comprises at least one anion selected from the group consisting of sulfate, dihydrogenphosphate, and phosphate; and at least one cation selected from the group consisting of sodium, potassium, calcium, aluminum, zinc and ammonium cations, and mixtures thereof.

17. The process according to claim 1, wherein the Mw is greater than 100,000 g/mol.

18. The process according to claim 1, wherein the aqueous dispersion has a polymer concentration ranging from 20 to 60 percent by weight.

19. The process according to claim 1, wherein the water-soluble polymer is in a form of particles having dimensions between 100 nm and 20 microns.

Description

EXAMPLES

(1) The synthesis is carried out in two steps: 1. Synthesis of a living poly(sodium 2-acrylamido-2-methylpropanesulfonate) prepolymer P1 2. Preparation of a homogeneous water-in-water dispersion of acrylamide/acrylic acid copolymers

Step 1: Synthesis of a Living poly(sodium 2-acrylamido-2-methylpropanesulfonate) prepolymer P1

(2) 320 g of sodium 2-acrylamido-2-methylpropanesulfonate (AMPS 2405 50%), 188 g of distilled water, 3.3 g of O-ethyl-S-(1-methoxycarbonylethyl) xanthate of formula (CH.sub.3CH(CO.sub.2CH.sub.3))S(C═S)OEt, 146 g of ethanol and 1.12 g of ACP (4′4-azobis-4-cyanovaleric acid) initiator were placed, at ambient temperature (20° C.), in a 1-liter round-bottomed flask. The mixture was degassed by sparging with nitrogen for 30 minutes. The round-bottomed flask was then placed in a thermostated oil bath at 75° C., and the polymerization reaction was then allowed to take place with stirring for 4 hours at 75° C.

(3) 100% conversion was obtained (determined by .sup.1H NMR). The number-average molar mass of the prepolymer P1, determined by .sup.1H NMR, is 15 537 g/mol.

(4) The solvent was evaporated off under vacuum using a rotary evaporator (15 mbar, 50° C.) and dried for 120 minutes at 50° C. Water was then added so as to have a solution of prepolymer at 25%. The dry extract measured after solvent exchange is 25% (115° C., 60 min)—SOLUTION A.

Step 2 Preparation of a Homogeneous Water-in-Water Dispersion Of Acrylamide/Acrylic Acid Copolymers

Example A Poly(Acrylamide/Acrylic Acid) 70/30 mol %

(5) Conditions:

(6) Prepolymer 1/poly(acrylamide/acrylic acid)=30% by weight.

(7) Poly(Acrylamide/Acrylic Acid) concentration=14.9% by weight.

(8) 24 g of solution A, 27.88 g of acrylamide (aqueous solution at 50% by weight), 6.06 g of acrylic acid, 3.48 g of sodium sulfate, 18.60 g of ammonium sulfate, 8 g of glycerol, 45.18 g of distilled water and 0.35 g of sodium hydroxide (aqueous solution at 50% by weight) were placed in a 250 ml round-bottomed flask, at ambient temperature (20° C.). The mixture was degassed by sparging with nitrogen with stirring for 30 minutes. After having added 0.045 g of VA044 (2,2′-azobis[2-(2-imidazolin-2-yl)propane]dihydrochloride), the round-bottomed flask was placed in a thermostated oil bath at 30° C., still with stirring. After reaction for 4 hours, a further 0.045 g of VA044 was added. The polymerization reaction was then left to proceed, still with stirring, at 38° C. for an additional 3 hours and 30 minutes.

(9) At the end of the 8 hours and thirty minutes of reaction, a conversion of >99.9% was obtained for acrylic acid and for acrylamide (conversions determined by HPLC). An analysis by size exclusion chromatography in an aqueous buffer solution of 100 mM NaCl, 25 mM NaH.sub.2PO.sub.4 and 25 mM Na.sub.2HPO.sub.4, pH 7, with a Malls 3 angle detector gives the following weight-average molar mass (M.sub.W) and polydispersity index values: M.sub.w=>210 000 g/mol PI=>1.4

(10) Using an analyzing polarizing microscope, the particle size was estimated between 1 and 3 μm,

(11) The product is stable after 8 months of storage at ambient temperature.

Example B Poly(Acrylamide/Acrylic Acid) 70/30 mol %

(12) Conditions:

(13) Prepolymer 1/poly(acrylamide/acrylic acid)=30% by weight.

(14) Poly(Acrylamide/Acrylic Acid) concentration=15.0% by weight.

(15) 24 g of solution A, 27.88 g of acrylamide (aqueous solution at 50% by weight), 6.06 g of acrylic acid, 3.48 g of sodium sulfate, 18.60 g of ammonium sulfate, 52.79 g of distilled water and 0.35 g of sodium hydroxide (aqueous solution at 50% by weight) were placed in a 250 ml round-bottomed flask, at ambient temperature (20° C.). The mixture was degassed by sparging with nitrogen with stirring for 30 minutes. After having added 0.045 g of VA044 (2,2′-azobis[2-(2-imidazolin-2-yl)propane] dihydrochloride), the round-bottomed flask was placed in a thermostated oil bath at 38° C., still with stirring. After reaction for 4 hours, a further 0.045 g of VA044 was added. The polymerization reaction was then left to proceed, still with stirring, at 38° C. for an additional 3 hours and 30 minutes.

(16) At the end of the 8 hours and thirty minutes of reaction, a conversion of 99.8% was obtained for acrylic acid and of 100% was obtained for acrylamide (conversions determined by HPLC). An analysis by size exclusion chromatography in an aqueous buffer solution of 100 mM NaCl, 25 mM NaH.sub.2PO.sub.4 and 25 mM Na.sub.2HPO.sub.4, pH 7, with a Malls 3 angle detector gives the following weight-average molar mass (M.sub.W) and polydispersity index values: M.sub.w=>156 000 g/mol PI=>1.2

(17) Using an analyzing polarizing microscope, the particle size was estimated between 1 and 3 μm.

(18) The product is stable after 8 months of storage at ambient temperature.

Example C Poly(Acrylamide/Acrylic Acid) 70/30 mol %

(19) Conditions:

(20) Prepolymer 1/poly(acrylamide/acrylic acid)=23% by weight.

(21) Poly(Acrylamide/Acrylic Acid) concentration=15.4% by weight.

(22) 18.4 g of solution A, 3.37 g of sodium sulfate, 18 g of ammonium sulfate and 0.35 g of sodium hydroxide (aqueous solution at 50% by weight) were placed in a 250 ml round-bottomed flask, at ambient temperature (20° C.). The mixture was degassed by sparging with nitrogen with stirring for 30 minutes. After having added 0.045 g of VA044 (2,2′-azobis[2-(2-imidazolin-2-yl)propane] dihydrochloride), the round-bottomed flask was placed in a thermostated oil bath at 38° C., still with stirring. The introduction of a solution containing 27.88 g of acrylamide (aqueous solution at 50% by weight) and 6.06 g of acrylic acid is jointly begun, at a flow rate of 0.113 ml/min. After reaction for 4 hours, a further 0.045 g of VA044 was added. The polymerization reaction was then left to proceed, still with stirring, at 38° C. for an additional 3 hours and 30 minutes.

(23) At the end of the 8 hours and thirty minutes of reaction, a conversion of 99.7% was obtained for acrylic acid and of 100% was obtained for acrylamide (conversions determined by HPLC). An analysis by size exclusion chromatography in an aqueous buffer solution of 100 mM NaCl, 25 mM NaH.sub.2PO.sub.4 and 25 mM Na.sub.2HPO.sub.4, pH 7, with a Malls 3 angle detector gives the following weight-average molar mass (M.sub.W) and polydispersity index values: M.sub.w=>380 000 PI=>1.9

(24) The chromatograms of the copolymers clearly show the presence of the two species: the acrylamide/acrylic acid copolymer and prepolymer P1.

Example D Poly(Acrylamide/Acrylic Acid) 70/30 mol %

(25) Conditions:

(26) Prepolymer 1/poly(acrylamide/acrylic acid)=40% by weight.

(27) Poly(Acrylamide/Acrylic Acid) concentration=22.1% by weight.

(28) 48 g of solution A, 2.81 g of sodium sulfate, 15 g of ammonium sulfate, 18.6 g of distilled water and 0.35 g of sodium hydroxide (aqueous solution at 50% by weight) were placed in a 250 ml round-bottomed flask, at ambient temperature (20° C.). The mixture was degassed by sparging with nitrogen with stirring for 30 minutes. After having added 0.068 g of VA044 (2,2′-azobis[2-(2-imidazolin-2-yl)propane] dihydrochloride), the round-bottomed flask was placed in a thermostated oil bath at 38° C., still with stirring. The introduction of a solution containing 41.82 g of acrylamide (aqueous solution at 50% by weight) and 9.09 g of acrylic acid is jointly begun, at a flow rate of 0.1697 ml/min. After reaction for 4 hours, a further 0.068 g of VA044 was added. The polymerization reaction was then left to proceed, still with stirring, at 38° C. for an additional 3 hours and 30 minutes.

(29) At the end of the reaction, a homogeneous dispersion is obtained despite a high polymer dry extract (22.1%).