SiC(Al)陶瓷纤维先驱体聚铝碳硅烷的合成与表征

SYNTHESIS AND CHARACTERIZATION OF PRECURSOR POLYALUMINOCARBOSILANE TO SiC(Al) CERAMIC FIBERS

利用聚二甲基硅烷(PDMS)热解聚合的液相产物聚硅碳硅烷(PSCS)与乙酰丙酮铝(Al(AcAc)3)反应制备了SiC(Al)陶瓷纤维的先驱体聚铝碳硅烷(PACS)。选用PSCS为原料消除了Al(AcAc)3在合成反应过程中出现的升华现象。合成的PACS化学式为:SiC2.0H7.6O0.13Al0.018,数均分子量Mn=2265。研究反应过程发现PSCS发生裂解重排反应,Si-H键在反应中显示出巨大的活性,反应时伴随有乙酰丙酮气相副产物产生。反应机理研究表明,PACS分子量的增加是PSCS形成的Si-H键与Al(AcAc)3的配位基发生交联反应形成Si-Al键的结果。

The precursor Polyaluminocarbosilane (PACS) to SiC(Al) ceramic fibers was synthesized by the reaction of Aluminum acetylacetonate (Al(AcAc)_3) with polysilacarbosilane (PSCS), which was prepared by the thermolysis and condensation of polydimethylsilane (PDMS). The sublimation of Al(AcAc)_3 could be avoided by the use of PSCS as reactant. The empirical formula of PACS is SiC_(2.0)H_(7.6)O_(0.13)Al_(0.018), the number molecular weight is 2265. When the reaction of PSCS with Al(AcAc)_3 proceeds, an enormous decrease in the number of (Si-H) bonds in PSCS is observed, at the same time, gas acetylacetonate is a by-product of the reaction based on the ligands of Al(AcAc)_3, and after the reaction about half of ligands of Al(AcAc)_3 remains in the PACS. The reaction mechanism was found to be related to the increase in the molecular weight of PACS by the cross-linking reaction of (Si-H) bonds in PSCS with Al(AcAc)_3, which leads to the production of (Si-Al) bonds.