Novel soluble thermally stable silane-containing aromatic polyimides with reduced dielectric constant

Bis(p-aminophenoxy)diphenylsilane (BPS), bis(m-aminophenoxy)diphenylsilane (BMS) and bis(5-amino-1-naphthoxy)diphenylsilane (BAS) as three silane-diamines were prepared by the reactions of 4-aminophenol, 3-aminophenol, and 5-amino-1-naphthol respectively, with dichlorodiphenylsilane in the presence of triethylamine. The related silane-containing polyimides were prepared by two-step polycondensation reactions of these diamines with three different aromatic dianhydrides. All the polymers were characterized and their physical and thermal properties were studied. The polymers showed high thermal stability while their solubility was greatly increased in polar aprotic solvents. Wide angle X-ray diffraction showed that all the polyimides were almost amorphous. Also their dielectric constants were decreased due to the incorporation of softening and low-polarizing siloxane units into the polymer backbone.