. . . . . "ne chain, X is wherein R is C1-C8 alkyl or wherein each of R1 and R2 is a hydrogen or a halogen atom, and Y is wherein R3 and R4 are the same or different and each is a halogen atom, C1-C4 alkyl, or C1-C4 alkoxy, m and n are 0 or an integer from 1 to 4, and Z is a direct bond or a radical selected from the group consisting of wherein each of R5 and R6 independently of the other is a hydrogen atom," . .