Comparative study on morphology and properties of polyimide/silica hybrid films derived from different polymeric precursors

Hybrid films derived from two polymeric precursors of polyamic acid (HYBRID-PAA) and soluble polyimide (HYBRID-PI) were prepared via a sol–gel process from hydrolysed tetraethoxysilane (TEOS). The UV-vis and scanning electron microscopy results show that two sizes of silica particles were acquired from PAA, while a single size of silica particles was acquired from PI. This phenomenon was induced by the carboxyl group in PAA. The differential scanning calorimetry results show that the glass transition temperature (T _g) of the hybrid using PAA was 40°C higher than when using PI. The tensile strain stress test shows that the tensile strength and modulus of hybrid films from PAA are greater than that from PI; but the elongation at break of hybrid films from PAA is lower than that from PI. The dynamic mechanical analysis and thermal mechanical analysis tests further suggest that the thermal properties and mechanical properties are influenced by the morphology of hybrids.