Abstract
The effects of phenyltrichlorosilane [PTS] concentration, reaction temperature, and hydrophilicity of solvent on the chemical structure of poly (phenylsilsesquioxane) [PPSQ], which is synthesized by hydrolysis and subsequent dehydration condensation of PTS, were discussed. In the case of 0.75 mol/l PTS solution in chloroform, the hydrolysate thus obtained was the oligomer whose Mn determined by GPC was about 2000. The Mn became small as the PTS concentration was decreased. Lower concentration of PTS or more hydrophilic solvent such as tetrahydrofuran (THF) made lower the functionality, namely the number of OH groups per hydrolysate molecule, which was estimated by the determination of silanol groups by 1H NMR and the Mn, suggesting that a ladder-shaped oligomer with fewer defects was obtained under such conditions. In dehydration condensation process, a hydrolysate with lower functionality was polymerized into a desired soluble PPSQ in higher yield, and in the IR spectrum of the product, the peak assigned to the Si-O-Si stretching vibration on siloxane ladder sequence was observed more distinctly.
