Single-step synthesis of chemically cross-linked polysilastyrene and its conversion to β -silicon carbide

A new method for chemically cross-linking polysilastyrene using divinylbenzene as the cross-linking agent is reported. The procedure involves a single-step synthesis using the alkali-metal sodium to promote the polymerization of dimethyldichlorsilane in the presence of the comonomers phenylmethyldichlorosilane and divinylbenzene. The cross-linked polymer can be readily converted to β-SiC on pyrolysis at 1500° C. The β -SiC obtained by this procedure is nanocrystalline and has a grain-size distribution of 8-20 nm

Chemically cross-linked polysilanes as stable polymer precursors for conversion to silicon carbide

Cross-linked polysilanes were prepared by the co-polymerization of Me2SiCl2 or PhMeSiCl2 with varying amounts of divinylbenzene (2-15% by weight) using molten sodium as the dehalogenating agent. All the cross-linked polysilanes were stable to air and could be processed thermally for conversion to silicon carbide. Polymers containing from 5-15% of the cross-linking agent underwent a uniform shrinkage during thermal treatment (1500 ° C) to afford β -SiC in good yields. The ceramic was characterized by a variety of techniques including Raman and infrared spectroscopy, powder XRD, as well as Scanning Electron Microscopy (SEM)