MQ silicone resins were prepared through hydrolytic condensation of ethyl polysilicate or tetraethoxysilane and hexamethyl disiloxane. The unit ratio of the MQ resins was determined by Si-29-NMR. The relationship of t...MQ silicone resins were prepared through hydrolytic condensation of ethyl polysilicate or tetraethoxysilane and hexamethyl disiloxane. The unit ratio of the MQ resins was determined by Si-29-NMR. The relationship of the unit ratio of the product resins with that in the feed was studied. When the reaction was catalyzed by aqueous hydrochloric acid, and the unit ratio of M to Q in the feed was more than 1, the unit ratio of the product was usually lower than that of the feed. The MQ silicon with an unit ratio of M/Q > 2 could not be obtained. However, if the reaction was catalyzed by concentrated sulfuric acid and the reverse hydrolysis process was employed, MQ silicone resin with very high M/Q ratio was successfully prepared.展开更多
文摘MQ silicone resins were prepared through hydrolytic condensation of ethyl polysilicate or tetraethoxysilane and hexamethyl disiloxane. The unit ratio of the MQ resins was determined by Si-29-NMR. The relationship of the unit ratio of the product resins with that in the feed was studied. When the reaction was catalyzed by aqueous hydrochloric acid, and the unit ratio of M to Q in the feed was more than 1, the unit ratio of the product was usually lower than that of the feed. The MQ silicon with an unit ratio of M/Q > 2 could not be obtained. However, if the reaction was catalyzed by concentrated sulfuric acid and the reverse hydrolysis process was employed, MQ silicone resin with very high M/Q ratio was successfully prepared.
