An organic soluble polyimide was prepared from 3,3′-dihydroxybenzidine and 2,2-bis(phthalic anhydride)hexafluoropropane. The two hydroxy groups in the repeating unit of the polyimide thus prepared were utilized in attaching 4-nitro-4′-diphenylaminoazobenzene chromophores onto the main chain perpendicularly (or in an end-on fashion) or laterally (or in a side-on fashion) through either the oxydimethylene or oxyhexamethylene spacer. All the polymers revealed two strong absorptions: one λmax at 300 nm and the other λmax at 493 nm. The polymers, when electrically poled, showed 2nd order nonlinear optical properties, r33 = 9–23 pm V−1 at 1300 nm, r33 = 102–194 pm V−1 at 633 nm, and d33 = 59–109 pm V−1
at 1064 nm depending on their structure. The polymers bearing side-on attached chromophores revealed higher r33 values than those with end-on attached chromophores. Temporal stability of the former was also greater than that of the latter.
用 3,3′-
二羟基联苯胺和 2,2-双(
邻苯二甲酸酐)
六氟丙烷制备了一种有机可溶聚
酰亚胺。利用由此制备的聚
酰亚胺重复单元中的两个羟基,通过氧二
甲苯或氧六亚甲基间隔物,将 4-硝基-4′-二苯基
氨基
偶氮苯发色团垂直(或端对)或横向(或侧对)连接到主链上。所有聚合物都有两个强吸收峰:一个 λmax 波长为 300 纳米,另一个 λmax 波长为 493 纳米。聚合物在通电极化后显示出二阶非线性光学特性:1300 纳米波长处 r33 = 9-23 pm V-1,633 纳米波长处 r33 = 102-194 pm V-1,1064 纳米波长处 d33 = 59-109 pm V-1。侧面附着发色团的聚合物的 r33 值高于端面附着发色团的聚合物。前者的时间稳定性也高于后者。