Synthesis, characterization, and thermal properties of alternate copolymers containing N,N'-Bis(diphenylsilyl)tetraphenylcyclodisilazane

摘要

Hexamethyldisilazane was used as the starting material to synthesize N,N'-bis(hydroxydiphenylsilanyl)-tetraphenylcyclodisilazane (BHPTPC). By condensation polymerization of BHPTPC with alpha,omega-bis(dialkylamino)dimethylsiloxane, a series of alternate copolymers containing N, N'-bis(diphenylsilyl)tetraphenylcyclodisilazane was synthesized. GPC studies show that the highest molecular weight was obtained at a ratio of 1.005 : 1 (BHPTPC: alpha,omega)-bis(dimethylamino)dimethylsiloxane). Data of DSC indicate that the temperature of glass transition (T-g) and temperature of melting point (T-m) decreased with the increasing of dimethylsiloxane segments units. Three stages of degradation were found in the thermogravimetric analysis curves. The activation energy of the copolymer (with m=2, 3, and 7) was calculated by using Flynn-Wall-Ozawa method. The activation energy of the copolymer with m=2,3, and 7 at second stage is 214,211, and 184 kJ/mol, respectively. Isothermal gravimetric analysis shows that for the same temperature and the same time, the weight loss of the alternate copolymer was greatly less than that of common polydimethylsiloxane. (c) 2006 Wiley Periodicals, Inc. I Appl Polym Sci 103: 611-617, 2007