Patent ID: 7247691

Claim:
A copolymer comprising monomers copolymerized in the following percentages by weight, relative to the total weight of the copolymer: a) 45–90% by weight of a monomer of formula II wherein R F is a straight or branched-chain perfluoroalkyl group containing 4 to 20 carbon atoms, R 1 is H or CH 3 , R 2 is H or an alkyl group with 1 to 4 carbon atoms, and m and n are, independently of each other, an integer from 2 to 11; and b) 5–30% by weight of a monomer of formula III (R 2 ) 2 N—(CH 2 ) k —X 1 —C(═O)—C(R 1 )═CH 2 (III) in which the nitrogen atom is partially or completely quaternized or in the form of a salt and X 1 is O or N(R 2 ) and wherein R 1 and R 2 are defined as above, each R 2 is the same or different, and k is 2 to 4; and c) 0–10% by weight of at least one copolymerizable nonfluorinated vinyl monomer.