Patent ID: 8916058

Claim:
A fluorocopolymer having a molecular weight less than 10,000 g/mol comprising units represented by the following formula: wherein R f represents a perfluorinated alkyl group, optionally interrupted by oxygen, having 3 to 6 carbon atoms; each R 1 is independently chosen from a C 1 -C 20 hydrocarbylene; R 8 is chosen from a C 1 -C 20 hydrocarbyl or hydrogen; R 2 is chosen from hydrogen, fluorine, or a C 1 -C 4 ; s is 0 or 1; Y is benzyl or carbonyl; R B is a group with the formula C a N b O c S f H 2(a-e)+b+1-2d having a structure which incorporates at least one betaine group of the formula (N + —C n H 2n —CO 2 − ) or (N + —C n H 2n —SO 3 − ) wherein a is an integer from 4-25, b is an integer from 1 to 4, c is an integer from 2 to 15, d is an integer from 0 to 3, e is an integer from 0 to 4, f is an integer from 0 to 4, the sum of e and f is from 1 to 4; n is independently chosen from an integer from 1 to 5; and R 3 is chosen from hydrogen or a C 1 -C 4 hydrocarbyl; provided that 2(a−e)+b+1−2d equals an integer from 8 to 55; and x is an integer from 1 to 10, y is an integer from 4 to 200, and the ratio of y:x is at least 1:1; wherein the repeat unit containing R B is formed by reacting a betaine forming compound with the repeat unit of a monomer selected from 2-(dimethylamino)-1-[(dimethylamino)methyl]ethyl acrylate, 3-(dimethylamino)-2,2-dimethylpropyl acrylate, 2-(4-morpholinyl)ethyl acrylate, 2-(4-morpholinyl)ethyl methacrylate, 2-(1-piperidinyl)ethyl methacrylate, 2-(1-piperidinyl)ethyl acrylate, 3-(dimethylamino)propyl acrylate, 2-[bis(1-methylethyl)amino]ethyl methacrylate, 2-(dimethylamino)ethyl acrylate, 2-(diethylamino)ethyl acrylate, 2-(diethylamino)ethyl methacrylate, 1-methyl-4-(2-methyl-1-oxo-2-propenyl)-piperazine, 4-ethyenyl-N,N-dimethylbenzylamine, or N-(p-vinylbenzyl)dibutylamine.