Catalysis of Thermal Cure and Ceramization of Phenylethynyl-Terminated Oligosilane

Phenylethynyloligosilane (PEPSI), prepared by lithium condensation, was stable in liquid state after a bench life over one year, and PEPSI can be used as precursor of SiC–C ceramic. The thermal cure occurred readily through polymerization reaction of ethynyl groups and hydrosilylation of Si–H with ethynyl at 230–330 °C. Thermal cure was dramatically accelerated by catalyst addition; among the investigated catalysts of Fe(acac)₃, Co(acac)₃ and Ni(acac)₂, the highest catalysis performance was achieved for Ni(acac)₂. The effect of catalyst amount [1, 2 and 3 % Ni(acac)₂, respectively] on thermal cure and ceramization was studied using DSC, TGA, XRD, and SEM–EDS, etc. The results show: 1 % weight of catalyst Ni(acac)₂ was enough for catalytic thermal cure and pyrolysis; the thermal cure process showed a decrease in the initiation crosslinking temperature from 230 to 120 °C and the peak temperature from 280 to 155 °C; the ceramic yield was improved from 58 to 71 %; the ceramic crystallization was accelerated by catalytic sintering of Ni(acac)₂.