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 Si OH 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 ( T g ): 328 °C, maximum decomposition occurring temperature ( T max ): 603 °C (N 2 ), coefficient of thermal expansion (CTE): 16.60 ppm/ o C).