Synthesis and characterization of silica-alumina co-doped polyimide film

A new class of polyimide/silica-alumina (PI/SiO₂-Al₂O₃) composite film was prepared by synthesizing ceramic oligomers through sol-gel reaction using tetraethoxysilane (TEOS) and heteropropyl-aluminium (HPAl) as the inorganic precursors and incorporating them into polyamic acid (PAA) derived from pyromellitic dianhydride (PMDA) and 4,4´-oxydianiline (ODA) in N,N-diethlacetanide (DMA_c). The chemical structure of the hybrid polyimide film was characterized by FTIR. And the surface morphology of the film was characterized by AFM. It turned out that a kind of co-doped polyimide film containing a homogeneous dispersion of SiO₂ and Al₂O₃ particles was obtained. And when the content of the inorganic moieties was not beyond 10% SiO₂ and 5% Al₂O₃ (wt%), the size of the ceramic particle was in the range of nano-level, besides, the film was golden and transparent.