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.

Key words: liquid polycarbosilane, polyaluminocarbosilane, aluminum acetylacetonate, structure characterization