Preparation of polyimide/silica hybrid composites based on polymer-modified silica gel

摘要

With a view to improve the affinity of silica particles for the polymer matrix, a new type of polyimide/silica (PI/SiO2) hybrid composite films has been successfully prepared using the polymer-modified silica gels. First, poly(maleic anhydride-co-styrene)/silica [P(MA-ST)/SiO2], polymer-modified silica gels, were prepared by the condensation reaction of the surface hydroxyl group of silica gel with a polymeric coupling agent, P(MA-ST)-trimethoxysilane. Then, PI/SiO2 hybrid films of different silica contents were obtained by the blending of polymer-modified silica gels with poly(amic acid) (PAA) from pyromellitic dianhydride (PMDA) and 4,4'-diaminodiphenyl ether (ODA) in N-methyl-2-pyrrolidinone (NMP). The decomposition temperature at 5 wt% loss (Td(5)) of the hybrid films, as measured by thermogravimetric analyses (TGA), increased with the increasing P(MA-ST)/SiO2 content within the measured range. The PI/SiO2 hybrid films with ca. 5 wt% of modified-silica exhibited balanced mechanical properties, whereas the hybrid films with higher silica contents had reduced mechanical properties, as confirmed by the scanning electron micrographs (SEM) observation.