the polymer chain and a side chain portion of the first segment having an orientation property, and the polymer matrix has a cross-linked structure wherein R1 and R2 are, respectively, H or an alkyl group of 2 or fewer carbon atoms, A is a group having at least a polyether group, and R3 is a group having at least an alkyl group of 6 or more carbon atoms, wherein R3 in the general formula (1) is a