Further investigations on precursors to Si-N-C-O ceramics: Progress June 1988--December 1988

Abstract

We have recently reported that polymethylsilylethylenediamine (PMSED) can serve as a precursor to silicon nitride and/or silicon carbonitride/silicon axycarbonitride. The procedure used for the preparation of the polymer was that of Rochow and Minne, and in that procedure the silane to diamine ratio was 1:2 whereas the product (polymer) yield was about 50%. Since condensation of dichlorosilanes with diamines are known to result in mixed cyclic and acyclic structures, we were interested in exploring the various conditions under which cyclic structures would predominate over acyclic ones and vice versa. This communication thus deals with the cyclic to acyclic ratios, the percent cyclic, percent yields that are obtainable under different reaction conditions. We have also prepared poly(hexamethyldisilazanyl)-silyl-ethylenediamine (PHMDSSED), which should be essentially acyclic, to determine its decomposition behavior vis a vis that of PMSED. 6 refs., 8 figs., 1 tab.