PREPARATION METHOD OF POLYMETHYLSILSESQUINOXANE COPOLYMER UNIFORMLY INTRODUCED WITH DIMETHYLSILOXANE GROUP

摘要

PURPOSE: A method for preparing a polymethylsilsesquinoxane copolymer uniformly introduced with a dimethylsiloxane group is provided, to allow a dimethylsiloxane group to be uniformly dispersed in a methylsiloxane structure in molecular level. CONSTITUTION: The method comprises the steps of mixing methyltrialkoxysilane (T structure) and dimethyldichlorosilane (D structure) in the molar ratio of 2:1 and heating the mixture at 100-150 deg.C for 5-20 hours to prepare a T-D-T-type precursor of methyltrialkoxysilane and dimethyldichlorosilane; adding methyltrialkoxysilane to the T-D-T-type precursor to make the ratio of methyl siloxane group/dimethyl siloxane group be 0.95/0.05 to 0.70/0.30 by mol, and adding water in an organic solvent mixture of tetrahydrofuran and toluene at 0-60 deg.C to react them by a sol-gel method; and adding diluted liquid ammonia to the obtained mixture solution to neutralize it to the pH 6-7.