| abstract |
Disclosed is a copolymer including a monomer unit (a) derived from a compound represented by the formula (1) and a monomer unit (b) derived from a compound represented by the formula (2), and having a weight average molecular weight (Mw) of from 1,000 to 50,000 n nwherein R 1 represents a hydrogen atom or a methyl group, R 2 represents a hydrogen atom, a linear alkyl group having from 1 to 8 carbon atoms, or a branched alkyl group having from 3 to 8 carbon atoms, R 3 , R 4 , R 5 , R 6 , R 7 and R 8 may be the same or different, at least one of those groups represents an aliphatic hydrocarbon group having from 3 to 8 carbon atoms, and the remainder represents a hydrogen atom or an aliphatic hydrocarbon group having 1 or 2 carbon atoms. |