Preparation and Properties of Imidazole-containing Polyimide/Silica Hybrid Films

Imidazole-containing polyimide/silica(PI/SiO2) hybrid films were prepared from 3,3', 4,4'-biphenyltetracarboxylic dianhydride(BPDA) and 2,2'-di(p-aminophenyl)-5,5'-bibenzimidazole in N, N-dimethylacetamide(DMAc) by sol-gel method and thermal imidization. The hybrid film with high silica mass fraction up to 40% was transparent. Scanning electron microscope(SEM) and transmission electron microscope(TEM) results of the film indicate a homogeneous dispersion of silica nanoparticles in the polyimide matrix. One hybrid film PI/SiO2 with 15% SiO2 exhibits better mechanical properties with a tensile strength of 222 MPa, an elongation at break of 12%, and a tensile modulus of 5.66 GPa. The reinforced mechanism on mechanical properties was also studied.