Photoconductive polyimides derived from a novel imidazole-containing diamine

A new diamine containing an imidazole structure, 4,4′-(4,5-diphenyl-1H-imidazole-1,2-diyl)dianiline (DIMA), was synthesized to prepare photoconductive polyimides (PIs) with four types of dianhydrides such as 3,3′,4,4′-biphenyltetracarboxylic dianhydride, 4,4′-oxyduphthalic anhydride, 4,4′-(hexafluoroisopropylidene) diphthalic anhydride, and cyclobutane-1,2,3,4,-tetracarboxylic dianhydride, based on the fact that the imidazole ring is a useful n-type block with high electron-donating property and good thermal stability. The imidazole-containing diamine possesses high electron-donating properties due to the lone pair electrons at nitrogen, which affords a high hole-transport property. All the PIs prepared from DIMA were amorphous due to the large side group and kink structure of the diamine, optically transparent (transmittances of 92–98% at 450 nm), and exhibited high thermal stability (10% weight loss temperatures ranged 453–558°C).