High molar mass polysilazane : a new polymer

The ionic ring-opening polymerization of cyclosilazane monomers is studied. Various cyclosilazanes have been reacted with both anionic and cationic initiators. Whereas cyclotrisilazanes and cyclotetrasilazanes give an equilibrated polymerization analogous to that observed with cyclosiloxanes, cyclodisilazanes with tert-butyl, isopropyl, or ethyl groups on the nitrogen only oligomerize. When the nitrogen substituent is a methyl group and for various silicon substituents, high molar mass polymers are obtained by both anionic and cationic processes