Isocyanate-Modified Polysilazane Ceramic Precursors
J. Schwark
Numerous methods have been developed to prepare polysilazanes by the oligomerization of low molecular weight silazanes. These methods include base-catalyzed dehydrocyclodimerization, hydrosilylation, transition metal catalysis, and acid-catalyzed rearrangement. Few reports have appeared, however, describing the preparation of polysilazanes by the reaction of cyclic silazanes with organic electrophiles.
Liquid polysilazanes with a broad range of tailored viscosities have now been prepared by the reaction of cyclic silazanes with mono- and multi-functional isocyanates. These isocyanate-modified polysilazanes may be used in a variety of applications (e.g., binders, coatings, infiltrants) because their viscosity may be tailored to the desired end use.