Method for preparing polyaluminocarbosilane

Polyaluminocarbosilane (PACS) was synthesized directly by the one‐pot reaction of polydimethylsilane (PDMS) with aluminum acetylacetonate [Al(acac) 3 ] in an autoclave. In this closed system, all the aluminum in Al(acac) 3 was converted into PACS. Therefore, the content of aluminum could be readily controlled quantitatively. On the basis of Fourier transform infrared, 1 H‐NMR, 13 C‐NMR, 29 Si‐NMR, and 27 Al magic‐angle spinning NMR analysis, the reaction mechanism was proposed as follows: PDMS dissociated during pyrolysis to generate silicon free radicals, and then they reacted with Al(acac) 3 to yield PACS containing (SiO) n Al groups ( n = 4, 5, or 6). Meanwhile, these reactions resulted in the cleavage of OC and/or OC bonds in Al(acac) 3 . Some of the free‐radical fragments generated by this cleavage continued to react with the silicon free radicals and were incorporated into the structural units of PACS; the rest of them may have been converted into small oxygen‐containing compounds, which were removed in the subsequent processing after the reactions. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009