Two novel electrochromic aromatic polyimides (named as TPA-BIA-PI and TPA-BIB-PI, respectively) with pendent benzimidazole group were synthesized from 1,2-Diphenyl-N,N′-di-4-aminophenyl-5-amino-benzimidazole and 4-Amino-4′-aminophenyl-4″-1-phenyl-benzimidazolyl-phenyl-aniline with 4,4′-(hexafluoroisopropane) phthalic anhydride (6FDA) via two-step polymerization process, respectively. Then, polyimide films were prepared on ITO-conductive glass by electrostatic spraying, and their electrochromic properties were studied. The results showed that due to the π-π* transitions, the maximum UV–Vis absorption bands of TPA-BIA-PI and TPA-BIB-PI films were located at about 314 nm and 346 nm, respectively. A pair of reversible redox peaks of TPA-BIA-PI and TPA-BIB-PI films that were associated with noticeable color changed from original yellow to dark blue and green were observed in the cyclic voltammetry (CV) test. With increasing voltage, new absorption peaks of TPA-BIA-PI and TPA-BIB-PI films emerged at 755 nm and 762 nm, respectively. The switching/bleaching times of TPA-BIA-PI and TPA-BIB-PI films were 13 s/16 s and 13.9 s/9.5 s, respectively, showing that these polyimides can be used as novel electrochromic materials.
由 1,2-二苯基-N.N′-二-4-氨基苯基-5-氨基苯并咪唑和 4-氨基-4′-氨基苯基-4″-1-苯基-苯并咪唑合成了两种新型电致变色芳香族聚酰亚胺(分别命名为 TPA-BIA-PI 和 TPA-BIB-PI)、N′-di-4-aminophenyl-5-amino-benzimidazole 和 4-Amino-4′-aminophenyl-4″-1-phenyl-benzimidazolyl-phenyl-aniline 与 4,4′-(hexafluoroisopropane)phthalic anhydride (6FDA) 通过两步聚合工艺分别合成了带有下垂苯并咪唑基团的 TPA-BIA-PI 和 TPA-BIB-PI。然后,通过静电喷涂在 ITO 导电玻璃上制备了聚酰亚胺薄膜,并研究了它们的电致变色性能。结果表明,由于π-π*跃迁,TPA-BIA-PI 和 TPA-BIB-PI 薄膜的最大紫外可见吸收带分别位于约 314 nm 和 346 nm 处。在循环伏安法(CV)测试中,TPA-BIA-PI 和 TPA-BIB-PI 薄膜出现了一对可逆的氧化还原峰,并伴随着明显的颜色变化,由原来的黄色变为深蓝色和绿色。随着电压的升高,TPA-BIA-PI 和 TPA-BIB-PI 薄膜分别在 755 nm 和 762 nm 处出现了新的吸收峰。TPA-BIA-PI 和 TPA-BIB-PI 薄膜的切换/漂白时间分别为 13 秒/16 秒和 13.9 秒/9.5 秒,表明这些聚酰亚胺可用作新型电致变色材料。