METHOD FOR PREPARING POLYCARBOSILANE BY CATALYTIC REARRANGING

摘要

Provided is a method for preparing a polycarbosilane by cracking and rearranging a cyclic silane compound or chain polysilane under the catalysis of a boron-containing catalyst in a trace amount (less than 1 wt%). In the method, polydimethylsilane (denoted as PDMS) or a pyrolysis product thereof, i.e. a liquid silane-carbosilane compound (denoted as LPS), is used as the raw material, less than 1 wt% (with respect to the dosage of the raw material) of the boron-containing catalyst is added, and then the temperature is gradually increased to the reaction temperature to perform the pyrolysis/rearrangement reaction under normal pressure or high pressure so as to obtain solid polycarbosilane (PCS) having a higher ceramic yield. This method has a short reaction time, a high synthetic yield, a good product quality, simple equipment and a safe operation; and the polycarbosilane prepared is a precursor polymer for SiC, and can be used for the preparation of a SiC fibre and a SiC-based composite.