Indication of Local Phase Separation in Polyimide/Silica Hybrid Polymers

PI/SiO2 hybrid polymers involving the in situ generation of SiO2 particles through the sol/gel route have emerged as promising materials in many fields of modern technology thanks to their unique structural characteristics. In this paper their structural and dynamic properties were investigated by FT-IR and DMTA as a function of SiO2 content. All data consistently highlight a loosening of polymeric structure due to the presence of SiO2 nanoparticles and suggest a silica-induced structural change most probably due to a submicrometer scale SiO2 phase separation. Our results demonstrate how the analysis of sub-glass gamma-relaxation dynamics can be exploited to investigate submicro phase segregation in such materials.