Preparation and mechanical properties of novel polyimide/T-silica hybrid films

Polyimide/silica tube (PI/T-silica) hybrid films were successfully prepared from solution of polyamic acid (polyimide precursor) and silica tubes modified by coupling agent (γ-aminopropyltriethoxy silane, KH 550). Silica tubes were obtained by hydrolyzing tetraethyl orthosilicate (TEOS) using d,l-tartaric acid as a template. The morphology of silica tubes was investigated by transmission electron microscopy (TEM) and scanning electron microscopy (SEM). The results showed that the silica tubes were rectangle and 100–500 nm in width and their aspect ratio was 10–500. The effects of coupling agent and silica filler content on the mechanical properties were studied. The results showed that there existed the optimal coupling agent and silica contents leading to the highest mechanical properties. When the weight ratio of KH 550/T-SiO2 was equal to 1/10 and the T-silica content was 1 wt%, the mechanical properties of PI/T-SiO2 hybrids were markedly improved.