Effect of polyborazine additive on thermolysis of polyphenylsilane and polyvinylsilane

To improve the ceramic residue yields and processabilities of polyphenylsilane (PPS) and polyvinylsilane (PVS), polyborazine (PBN) was employed as an additive. The ceramic residue yield of PPS increased from an original 39wt% to 65wt%, and of PVS from an original 26wt% to 64wt% by simply heating with 1wt% PBN at 70 °C. Furthermore, low viscous PPS and PVS were transformed into highly viscous polymers, which were found to be suitable for hand drawing into green fibers. The enhanced properties were attributed to an increased molecular weight, as analyzed by GPC. 1H-NMR and 29Si-NMR spectra suggested that dehydrocoupling of SiH3 in PVS and SiH in PPS by PBN was responsible for the improved ceramic yields.