Pyrolysis chemistry of polysilazane precursors to silicon carbonitride .1. Thermal degradation of the polymers

The cross-linking reactions and the decomposition processes of three different polysilazane precursors to silicon carbonitride have been investigated systematically in the course of pyrolysis to 1400 degrees C. The polymer to ceramic conversion chemistry was studied for the following precursors: (ViSiHNH)(n) (VS), (ViSiHNMe)(n) (VNMS), [(ViSiHNH)(0.5)-(MeSiHNH)(0.5)](n) (VS/MS), by means of thermogravimetry, mass spectrometry, solid-state NMR and IR spectroscopies, elemental analysis and X-ray diffraction. The influence of the structure and the polymer backbone (the nature and distribution of the functional groups) on the conversion chemistry was investigated. The occurrence of the cross-linking reactions, the ceramic yields and the abundance of the free carbon phase are related to the polymeric precursor structures.