The effect of SiO2/Al2O3 weight ratio on the morphological and properties of polyimide/SiO2-Al2O3 ternary hybrid films

Polyimide/silica-alumina (PI/SiO₂-Al₂O₃) hybrid films were prepared via sol-gel process with tetraethoxysilane (TEOS) and aluminum isopropylate (AIP) as inorganic precursors. The presence of SiO₂ and Al₂O₃ inorganic phases and its weight ratio showed a remarkable effect on the microstructure and properties of the polyimide based hybrid films. The chemical structure of hybrid films was analyzed by Fourier transform infrared (FTIR) and the results showed that the completely hydrolysis of inorganic precursors and the formation of three dimensional Si-O-Al network in the hybrid films. The morphology and its distribution of inorganic phases in hybrid films were studied by scanning electron microscopy (SEM). The thermal and mechanical properties of the hybrid films were measured and compared to the pure PI. Results indicated that the incorporation of inorganic enhanced the thermal stability and mechanical properties of the hybrid films. However, the UV-vis transmittance of hybrid films was reduced.