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Precursors for silicon carbide synthesised from dichloromethylsilane derivatives
journal contributionposted on 14.09.2016 by Xujin Bao, Mohan J. Edirisinghe, Gerard F. Fernando, Michael J. Folkes
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Several polysilanes, including two groups of copolymers and a group of ter-polymers, with overall functionalities ranging between 2 and 3 were prepared using the alkali metal dechlorination reaction. The yields of the soluble solid fractions of these polymers (the potential ceramic precursor) were in the range 40–70% wt and decreased with increasing overall functionalities in both cases of co- and terpolymers. The molecular weights and FT-IR spectra of the precursors have been determined and the ceramic in the residue after pyrolysis has been identified as silicon carbide. The pyrolytic yield can be increased by using a polymeric precursor of higher overall functionality. The reasons for this are discussed with reference to pyrolysis mechanisms. In particular, some of the ter-polymeric precursors synthesised with a high yield also give a high yield on pyrolysis due to the presence of branched structures and potential cross-linking sites.
The authors wish to thank the Soft Solids Initiative of EPSRC for funding this project (EPSRC Grant No. GR/L21976).
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