Patent ID: 6861197

Claim:
A polymer containing a group of the following formula (1) and having a weight average molecular weight of 1,000 to 500,000, wherein R 1 is hydrogen, fluorine or a straight, branched or cyclic alkyl or fluorinated alkyl group of 1 to 20 carbon atoms, and R 2 and R 3 bond together to form a ring such that each is an alkylene group of 1 to 20 carbon atoms which optionally contains an oxygen, sulfur or nitrogen hetero atom, R 4 and R 5 each are hydrogen or fluorine, R 6 and R 7 each are hydrogen, fluorine or a straight, branched or cyclic alkyl or fluorinated alkyl group of 1 to 20 carbon atoms, in which case at least one of R 6 and R 7 is a fluorinated alkyl group of 1 to 20 carbon atoms, or alternatively R 6 and R 7 bond together to form a ring and in that event, each is a straight, branched or cyclic alkylene or fluorinated alkylene group of 1 to 20 carbon atoms, and “a” is 0 or 1.