Preparation of liquid polycarbosilane containing vinyl ether group and its rapid curing through thiol-ene click reaction

In this study, an SiC ceramic precursor vinyl ether-grafted liquid polycarbosilane (VE-LHBPCS) with approximate formulas of [SiH1.95(OCH2CH2OCH = CH2)(0.05)CH2](n) was designed and synthesized. In order to cross-link the ceramic precursor via fast thiol-ene click reaction. The VE-LHBPCS was mixed with 1-wt% ultraviolet (UV) decomposable free radical initiator BAPOs and 7-wt% bis-thiol compound 1,6-hexanedithiol. According to Fourier transform infrared spectroscopy spectroscopy and photolithography experiment, more than 80% vinyl ether group was consumed within 3 s, and photolithography pattern with clear boundary could be formed after UV irradiation for only 1 s. Even for the VE-LHBPCS mixture with a thickness of 4 mm, 20-s UV irradiation was sufficient to cure it with smooth surface and regular edge. Thermal gravimetric analysis demonstrated that the UV-cured VE-LHBPCS mixture had a ceramic yield of 70.0 wt% at 1000 degrees C, which was 20 wt% higher than that of raw LHBPCS. After pyrolysis up to 1000 degrees C, about 29.5% isotropic linear shrinkage associated with the precursor-to-ceramic conversion was observed, and black dense ceramic with a density of 2.49 +/- 0.09 g/cm(3) and a chemical formula of SiC1.01O0.18S0.04 was obtained. With increasing the pyrolysis temperature, the content of element S decreased and the diffraction peaks of beta-SiC became sharper and stronger.

Automated summary

In this study, an SiC ceramic precursor, VE-LHBPCS, was designed and synthesized. The ceramic precursor was cross-linked via thiol-ene click reaction. The results showed that the VE-LHBPCS mixture could be cured within a short period of time, forming a high yield ceramic at high temperatures.