Disclosed therein are a photoreactive polymer, and an alignment layer comprising the same that exhibit excellences in alignment rate and alignment stability. The photoreactive polymer comprises a cyclic olefin-based repeating unit with at least one photoreactive substituent, and the maximum absolute value of a variation in dichloric ratio per unit UV dose as given by d(dichloric ratio)/d(mJ/cm
2
) upon exposure to a polarized UV radiation having a wavelength of 150 to 450 nm at a total exposure dose of 20 mJ/cm
2
or less is at least 0.003.
其中公开了一种光敏聚合物和包含该聚合物的定向层,具有优异的对准速率和对准稳定性。该光敏聚合物包含至少一个光敏取代基的环烯烃基重复单元,且在暴露于波长为150至450纳米的偏振紫外辐射下,总暴露剂量为20 mJ/cm2或更少时,每单位紫外线剂量所给出的二
氯比率变化的最大绝对值为d(dichloric ratio)/d(mJ/cm2)至少为0.003。