A polymer of the formula or, wherein each R is independently a linear or branched C 1 -C 10 -alkyl, which is unsubstituted or substituted with 1, 2 or 3 substituents selected from the group consisting of halogen, CN, NO 2, OH, O(C 1 -C 4 -alkyl), NH 2, NH(C 1 -C 4 -alkyl), N(C 1 -C 4 -alkyl) 2, and phenyl; or phenyl, which is unsubstituted or substituted with 1, 2 or 3 substituents selected from the group consisting of halogen, CN, NO 2, OH, O(C 1 -C 4 -alkyl), NH 2, NH(C 1 -C 4 -alkyl), N(C 1 -C 4 -alkyl) 2, C 1 -C 4 -alkyl, and CF 3; R 1 is a linear or branched C 1 -C 10 -alkyl, which is unsubstituted or substituted with 1, 2 or 3 substituents selected from the group consisting of halogen, CN, NO 2, OH, O(C 1 -C 4 -alkyl), NH 2, NH(C 1 -C 4 -alkyl), N(C 1 -C 4 -alkyl) 2, and phenyl; each R 2 is independently a linear or branched C 1 -C 10 -alkyl, which is unsubstituted or substituted with 1, 2 or 3 substituents selected from the group consisting of halogen, CN, NO 2, OH, O(C 1 -C 4 -alkyl), NH 2, NH(C 1 -C 4 -alkyl), N(C 1 -C 4 -alkyl) 2, and phenyl; each Ar is independently phenyl, which is unsubstituted or substituted with 1, 2 or 3 substituents selected from the group consisting of halogen, CN, NO 2, OH, O(C 1 -C 4 -alkyl), NH 2, NH(C 1 -C 4 -alkyl), N(C 1 -C 4 -alkyl) 2, C 1 -C 4 -alkyl, and CF 3; biphenyl, which is unsubstituted or substituted with 1, 2 or 3 substituents selected from the group consisting of halogen, CN, NO 2, OH, O(C 1 -C 4 -alkyl), NH 2, NH(C 1 -C 4 -alkyl), N(C 1 -C 4 -alkyl) 2, C 1 -C 4 -alkyl, and CF 3; or naphthyl, which is unsubstituted or substituted with 1, 2 or 3 substituents selected from the group consisting of halogen, CN, NO 2, OH, O(C 1 -C 4 -alkyl), NH 2, NH(C 1 -C 4 -alkyl), N(C 1 -C 4 -alkyl) 2, C 1 -C 4 -alkyl, and CF 3; k is an integer from 1 to 8; n is an integer from 5 to 1000; x is an integer from 3 to 500; y is an integer from 3 to 500. each R is independently a linear or branched C 1 -C 10 -alkyl, which is unsubstituted or substituted with 1, 2 or 3 substituents selected from the group consisting of halogen, CN, NO 2, OH, O(C 1 -C 4 -alkyl), NH 2, NH(C 1 -C 4 -alkyl), N(C 1 -C 4 -alkyl) 2, and phenyl; or phenyl, which is unsubstituted or substituted with 1, 2 or 3 substituents selected from the group consisting of halogen, CN, NO 2, OH, O(C 1 -C 4 -alkyl), NH 2, NH(C 1 -C 4 -alkyl), N(C 1 -C 4 -alkyl) 2, C 1 -C 4 -alkyl, and CF 3; R 1 is a linear or branched C 1 -C 10 -alkyl, which is unsubstituted or substituted with 1, 2 or 3 substituents selected from the group consisting of halogen, CN, NO 2, OH, O(C 1 -C 4 -alkyl), NH 2, NH(C 1 -C 4 -alkyl), N(C 1 -C 4 -alkyl) 2, and phenyl; each R 2 is independently a linear or branched C 1 -C 10 -alkyl, which is unsubstituted or substituted with 1, 2 or 3 substituents selected from the group consisting of halogen, CN, NO 2, OH, O(C 1 -C 4 -alkyl), NH 2, NH(C 1 -C 4 -alkyl), N(C 1 -C 4 -alkyl) 2, and phenyl; each Ar is independently phenyl, which is unsubstituted or substituted with 1, 2 or 3 substituents selected from the group consisting of halogen, CN, NO 2, OH, O(C 1 -C 4 -alkyl), NH 2, NH(C 1 -C 4 -alkyl), N(C 1 -C 4 -alkyl) 2, C 1 -C 4 -alkyl, and CF 3; biphenyl, which is unsubstituted or substituted with 1, 2 or 3 substituents selected from the group consisting of halogen, CN, NO 2, OH, O(C 1 -C 4 -alkyl), NH 2, NH(C 1 -C 4 -alkyl), N(C 1 -C 4 -alkyl) 2, C 1 -C 4 -alkyl, and CF 3; or naphthyl, which is unsubstituted or substituted with 1, 2 or 3 substituents selected from the group consisting of halogen, CN, NO 2, OH, O(C 1 -C 4 -alkyl), NH 2, NH(C 1 -C 4 -alkyl), N(C 1 -C 4 -alkyl) 2, C 1 -C 4 -alkyl, and CF 3; k is an integer from 1 to 8; n is an integer from 5 to 1000; x is an integer from 3 to 500; y is an integer from 3 to 500.