不同温度下聚铝碳硅烷的合成与表征

为了研究合成温度对聚铝碳硅烷(PACS)结构的影响, 采用具有Si—C骨架结构的低分子量液态聚碳硅烷(LPCS)与乙酰丙酮铝[Al(AcAc)3]为原料, 在300, 360和420 ℃下分别合成了固态PACS, 并对合成的PACS样品进行元素组成及结构表征. 表征结果显示, 合成温度明显影响样品的Al, O含量及Si—H键数量. 合成温度升高, Al含量与O含量增大, 但PACS中的Si—H键数量急剧减少, 在360 ℃下合成的样品具有理论Al含量, 而在300和420 ℃下合成的样品的Al含量分别小于和大于理论Al含量. 27Al MAS NMR结果显示, Al与O形成AlO4, AlO5和AlO6 三种配位形式. 反应过程中消耗Si—H键形成Si—O—Al交联结构是PACS数均分子量及多分散系数增加的主要原因.

Preparation and Characterization of Polyaluminocarbosilane at Different Temperatures

Polyaluminocarbosilanes (PACS) were synthesized by reacting liquid polycarbosilane (LPCS) with aluminum acetylacetonate [Al(AcAc)3] at 300, 360 and 420 ℃, respectively. Chemical elemental analysis results indicated that the Al contents in PACS were almost equal to the theoretical Al content calculated from the proportioning of reactants when PACS was synthesized at 360 ℃, but became less and more than the theoretical Al content when PACS was synthesized at 300 and 420 ℃, respectively. The Al and O contents increased when the reactive temperature increased. The results of structure analysis suggested that Al in the PACS existed in the forms of AlO4, AlO5 and AlO6. The LPCS reacted with Al(AcAc)3 by consuming Si—H bonds, and forming Si—O—Al crosslinking bonds, leading to the increases in the number average molecular weight and poly-dispersion index of PACS. Then the possible mechanism of LPCS reacting with Al(AcAc)3 was proposed.