A copolymer includes structural units having the following formulae (1) and (2):
wherein each of R1 and R2 independently represents a hydrogen atom or a methyl group; X represents a hydrogen atom or a cationic ion; and L represents a single bond or —(CH
2
)
n
—O—, the oxygen atom of which is bonded with the biphenyl; and n represents an integer of from 2 to 18.
一种共聚物,包括具有以下式(1)和(2)的结构单元:其中R1和R2各自表示氢原子或甲基基团;X表示氢原子或阳离子离子;L表示单键或-(
CH2)n-O-,其中氧原子与
联苯键合;n表示2至18的整数。