Synthesis of Polysilazane from Isocyanato (methyl) silanet

Abstract

The reaction of triisocyanato (methyl) silane with ammonia in diethyl ether, tetrahydrofuran or pyridine was investigated. Isocyanato (methyl) silazane was isolated as a white powder soluble in organic solvents after removal of the oligomers by means of reprecipitation. The isolated polysilazane was unstable and easily polymerizable and was composed of the unit structures of MeSi (NH)_X/2(NCO)_3-X( X =1, 2, 3)with a number average molecular weight of 500. However, the reaction of methylisocyanatopolysilazane with amine provided silylurea derivatives of polysilazane with a softening point, spinnability, and stability against condensation.