Preparation and characterization of adenine-based polyimide/nano-silica hybrid films

To broaden the application of polyimide materials, adenine-based polyimide/nano-silica hybrid films were prepared via sol-gel method without using coupling agents. Adenine-based diamine, 9,10-bis(4-aminopheny)adenine (p-APA), was introduced to polymerize with 3,3′,4,4′-tetracarboxydiphthalic ether dianhydride (ODPA) to synthesize polyimide (API) matrix. The compatibility between the polymer matrix and silica was improved by hydrogen bonding between NH group in p-APA and SiOH group in silica. Systematic studies showed that API hybrid films possess high transparency and outstanding thermal properties even though the doping content was up to 20 wt% (glass transition temperature (Tg): 328 °C, maximum decomposition occurring temperature (Tmax): 603 °C (N2), coefficient of thermal expansion (CTE): 16.60 ppm/oC).