NOVEL COMB COPOLYMER AND PROCESS FOR THE PREPARATION THEREOF

Abstract

A comb copolymer having a backbone of 2-acrylamido-2-methylpropanesulfonic acid or a derivative thereof, with grafted lateral side segments of poly(N-alkylacrylamide) or poly(N,N-dialkylacrylamide), is provided. A process for the preparation of the comb copolymer includes reacting a compound of formula (II) with a compound of formula (III) in a (tert-butanol)-water mixture, to obtain a poly(N-alkylacrylamide) or poly(N,N-dialkylacrylamide) telomere of formula (I); reacting in tert-butanol the telomer of formula (I) with an acid chloride of formula (IV) to obtain a solution of the macromonomer of formula (V); and copolymerising in tert-butanol the macromonomer of formula (V) with an ammonium salt of 2-acrylamido-2-methylpropanesulfonic acid.

Claims

1. A method for the preparation of a comb copolymer, the comb copolymer comprising a backbone comprising 2-acrylamido-2-methylpropanesulfonic acid or a derivative thereof, with grafted poly(N-alkylacrylamide) or poly(N,N-dialkylacrylamide) side segments, the method comprising the following successive stages: (a) reaction of a compound of formula (II):
CH.sub.2C(R.sub.2)C(O)N(R.sub.3)(R.sub.4)(II) in which R.sub.2 represents a hydrogen atom or a methyl group, R.sub.3 represents a hydrogen atom or a linear or branched alkyl radical comprising from 1 to 4 carbon atoms, and R.sub.4, which is identical to or different from R.sub.3, represents a linear or branched alkyl radical comprising from 1 to 4 carbon atoms, with a chain-limiting compound of formula (III):
ZR.sub.1NH.sub.2(III) in which R.sub.1 represents a divalent radical comprising from 1 to 4 carbon atoms and Z represents a functional group capable of acting as radical transfer agent, in the presence of a polymerization initiator, in a tert-butanol/water mixture, to obtain a poly(N-alkylacrylamide) or poly(N,N-dialkylacrylamide) telomer of formula (I):
H.sub.2NR.sub.1Z{CH.sub.2C(R.sub.2)[C(O)N(R.sub.3)(R.sub.4)]}.sub.nH(I) in which n represents an integer greater than or equal to 2 and less than or equal to 100 and Z represents a functional group capable of acting as radical transfer agent; optionally (b) isolation and/or of drying of said telomer of formula (I) obtained in stage (a); (c) reaction in tert-butanol of the telomer of formula (I) obtained in stage (a) or optionally in stage (b) with an acid chloride of formula (IV):
CH.sub.2C(R.sub.5)C(O)Cl(IV) in which R.sub.5 represents a hydrogen atom or a methyl radical, in a (IV)/(III) molar ratio of 1 to 10 inclusive, while maintaining the pH of the reaction medium at a value of between 8 and 10, to obtain a solution of a macromonomer of formula (V):
CH.sub.2C(R.sub.5)C(O)NHR.sub.1Z{CH.sub.2C(R.sub.2)[C(O)N(R.sub.3)(R.sub.4)]}.sub.nH(V), optionally (d) isolation and/or of drying of said macromonomer of formula (V) obtained in stage (c); (e) copolymerization in tert-butanol of the macromonomer of formula (V) resulting from stage (c) or from stage (d) with an ammonium salt of 2-acrylamido-2-methylpropanesulfonic acid, and optionally (f) purification of the comb copolymer obtained in stage (e).

2. The method as defined in claim 1, wherein in the formula (II), R.sub.2 and R.sub.3 each represent a hydrogen atom and R.sub.4 represents an isopropyl radical.

3. The method as defined in claim 1, wherein said side segments are selected from the group consisting of poly(N-methylmethacrylamide) side segments, poly(N-ethylmethacrylamide) side segments, poly(N-propylmethacrylamide) side segments, poly(N-isopropylmethacrylamide) side segments, poly[N-(2-hydroxyethyl)methacrylamide] side segments, poly(N,N-dimethylmethacrylamide) side segments, poly(N,N-diethylmethacrylamide) side segments, poly(N-methylacrylamide) side segments, poly(N-ethylacrylamide) side segments, poly(N-propylacrylamide) side segments, poly(N-isopropylacrylamide) side segments, poly[N-(2-hydroxyethyl) acrylamide] side segments, poly(N,N-dimethylacrylamide) side segments, poly(N,N-diethylacrylamide) side segments, and combinations thereof.

4. The method as defined in claim 1, wherein said side segments are selected from the group consisting of poly(N-isopropylacrylamide) side segments, poly[N-(2-hydroxyethyl)acrylamide] side segments, poly(N,N-dimethylacrylamide) side segments, poly(N,N-diethylacrylamide) side segments, and combinations thereof.

Description

[0019] For this reason, according to a first aspect, a subject matter of the invention is a process for the preparation of a comb copolymer, the backbone of which is of the 2-acrylamido-2-methylpropanesulfonic acid (ATBS) type, to which poly(N-alkylacrylamide) or poly(N,N-dialkylacrylamide) side segments are grafted, characterized in that it comprises the following successive stages: [0020] a stage (a) of reaction of a compound of formula (II):

CH.sub.2C(R.sub.2)C(O)N(R.sub.3)(R.sub.4)(II)

in which R.sub.2 represents a hydrogen atom or a methyl group, R.sub.3 represents a hydrogen atom or a linear or branched alkyl radical comprising from 1 to 4 carbon atoms and R.sub.4, which is identical to or different from R.sub.3, represents a linear or branched alkyl radical comprising from 1 to 4 carbon atoms, with a chain-limiting compound of formula (III):

ZR.sub.1NH.sub.2(III)

in which R.sub.1 represents a divalent radical comprising from 1 to 4 carbon atoms and Z represents a functional group capable of acting as radical transfer agent, in the presence of a polymerization initiator, in a tert-butanol/water mixture, in order to obtain a poly(N-alkylacrylamide) or poly(N,N-dialkylacrylamide) telomer of formula (I):

H.sub.2NR.sub.1Z{CH.sub.2C(R.sub.2)[C(O)N(R.sub.3)(R.sub.4)]}.sub.nH(I)

in which n represents an integer greater than or equal to 2 and less than or equal to 100 and Z represents a functional group capable of acting as radical transfer agent; optionally [0021] a stage (b) of isolation and/or of drying of said telomer of formula (I) obtained in stage (a); [0022] a stage (c) of reaction in tert-butanol of the telomer of formula (I) obtained in stage (a) or optionally in stage (b) with an acid chloride of formula (IV):

CH.sub.2C(R.sub.5)C(O)Cl(IV)

in which R.sub.5 represents a hydrogen atom or a methyl radical, in a (IV)/(III) molar ratio of less than or equal to 10 and greater than or equal to 1, while maintaining the pH of the reaction medium at a value of between 8 and 10, in order to obtain a solution of the macromonomer of formula (V):

CH.sub.2C(R.sub.5)C(O)NHR.sub.1Z{CH.sub.2C(R.sub.2)[C(O)N(R.sub.3)(R.sub.4)]}.sub.nH(V)

optionally [0023] a stage (d) of isolation and/or of drying of said macromonomer of formula (V) obtained in stage (c); [0024] a stage (e) of copolymerization in tert-butanol of the macromonomer of formula (V) resulting from stage (c) or from stage (d) with the ammonium salt of 2-acrylamido-2-methylpropanesulfonic acid and, if desired; [0025] a stage (f) of purification of the comb copolymer obtained in stage (e).

[0026] tert-Butanol/water mixture denotes, in the process as defined above, a mixture for which the proportion by volume of water is less than or equal to 50%.

[0027] According to a specific aspect of the process as defined above, in the formula (II), R.sub.2 and R.sub.3 each represent a hydrogen atom and R.sub.4 represents an isopropyl radical.

[0028] Another subject matter of the invention is a comb copolymer, the backbone of which is of the 2-acrylamido-2-methylpropanesulfonic acid type, to which poly(N-alkyl(meth)acrylamide) or poly(N,N-dialkyl(meth)acrylamide) side segments are grafted, said side segments being chosen from the following side segments: [0029] poly(N-methylmethacrylamide) side segments, [0030] poly(N-ethylmethacrylamide) side segments, [0031] poly(N-propylmethacrylamide) side segments, [0032] poly(N-isopropylmethacrylamide) side segments, [0033] poly[N-(2-hydroxyethyl)methacrylamide] side segments, [0034] poly(N,N-dimethylmethacrylamide) side segments, [0035] poly(N,N-diethylmethacrylamide) side segments, [0036] poly(N-methylacrylamide) side segments, [0037] poly(N-ethylacrylamide) side segments, [0038] poly(N-propylacrylamide) side segments, [0039] poly(N-isopropylacrylamide) side segments, [0040] poly[N-(2-hydroxyethyl) acrylamide] side segments, [0041] poly(N,N-dimethylacrylamide) side segments, [0042] poly(N,N-diethylacrylamide) side segments,
and more particularly a comb copolymer as defined above in which said side segments are chosen from the following side segments: [0043] poly(N-isopropylacrylamide) side segments, [0044] poly[N-(2-hydroxyethyl)acrylamide] side segments, [0045] poly(N,N-dimethylacrylamide) side segments and [0046] poly(N,N-diethylacrylamide) side segments.

[0047] The following example illustrates the invention without, however, limiting it. It demonstrates that it is possible to prepare comb polymers without an acrylamide backbone comprising side segments of N-alkylacrylamide type which are heat-thickening.

Preparation of a comb copolymer comprising a backbone of ATBS type, to which poly(N-isopropylacrylamide) side segments are grafted ATBS-g-NIPAM

[0048] (1) Preparation of a poly(N-isopropyl acrylamide) telomer

[0049] 435 g of N-isopropylacrylamide (NIPAM) are dissolved in a tert-butanol/water mixture (50/50 by volume) in a thermostatically controlled reactor until 1000 g are reached, and stirring is carried out under nitrogen sparging for approximately one and a half hours. 2-Aminoethanethiol hydrochloride (AET.HCl) is subsequently added in a predetermined NIPAM/AET.HCl molar ratio of approximately 48/1. The polymerization is initiated with dilauroyl peroxide by bringing the temperature to 60 C. and then the reaction medium is left stirring and under nitrogen sparging for a further 2 hours. A white and pasty final reaction mixture is obtained.

[0050] (2) Preparation of the Macromonomer

[0051] A solution of potassium hydroxide (0.16 N) in tert-butanol and acryloyl chloride are added to the reaction medium obtained in stage (1) maintained at a temperature of 10 C., while maintaining the pH in the vicinity of 9. At the end of the reaction, the content of NIPAM macromonomer is 17.8% by weight and the water content is 10.7% by weight.

[0052] (3) Synthesis of the Copolymer

[0053] 61.8 g of the reaction medium obtained in stage (2) are diluted in 170 g of tert-butanol in the reactor thermostatically controlled at 15 C. 77 g of the ammonium salt of 2-acrylamido-2-methylpropanesulfonic acid and then 0.44 g of trimethylolpropane triacrylate are added thereto. The polymerization is initiated with dilauroyl peroxide and the medium is left stirring for four hours while maintaining the temperature at 60 C.

The polymer which precipitated during the polymerization is recovered by filtration. After drying, the desired copolymer is obtained in the powder form.

[0054] It is found that a 1% by weight solution of the polymer in water is slightly viscous. After heating above 80 C., there is formation of a gel, which is characteristic of a heat-thickening polymer.