含钛聚碳硅烷的合成、表征及其形成机理研究

Synthesis and mechanism of polytitanocarbosilane from LPCS and Ti(OBu)_4

以合成聚碳硅烷的副产品——液态小分子聚碳硅烷(LPCS)和钛酸正丁酯为原料,合成含钛聚碳硅烷,并通过产物的凝胶液相色谱、核磁、红外等表征方法研究其反应机理。研究表明,液态小分子聚碳硅烷的Si—H基团受热分解所形成的自由基,部分相互偶联,另一部分则与钛酸丁酯发生自由基取代反应,从而形成含钛聚碳硅烷,并因链的增长,分子量相应增大,最终形成主分子链由支化或交联度较高的链段所组成的含钛聚碳硅烷,具有较高的陶瓷产率,可以用作SiC陶瓷的先驱体。

Polytitanocarbosilane was synthesized from liquid polycarbosilane（LPCS） and tetrabutyl titanate（Ti（OBu）4）.They were characterized by gel permeation chromatography（GPC）,nuclear magnetic resonance（NMR） and Fourier transform infrared spectroscopy（FT-IR）.Based on these characterizations,the reaction mechanism was proposed as follows： the silicon free radicals were generated from Si—H group and then attacked the tetrabutyl titanate to form a branched or cross-linked network of silicon-containing fragment linked by Si—O—Ti group.The ceramic yield of the PTCS prepared in this way is very good.It can be used as the precursor for SiC ceramic composite matrix.