Synthesis and optical and thermal properties of poly [methyl(2,9-diphenyl-7,8-benzophenanthryl)silylene-co-1,4-bis(methylphenylsilyl)phenylene]

Poly[methyl(2,9-diphenyl-7,8-benzophenanthryl)silylene-co-1,4-bis(methylphenylsilyl)phenylene] (PMBS-co-BSP) was synthesized by the condensation reaction of dichloromethyl(2,9-diphenyl-7,8-benzophenanthryl)silane and 1,4-bis(chloromethylphenylsilyl)benzene with sodium in toluene. Optical and thermal behavior of the polymer was investigated. Because of the introduction of substituted benzophenanthryl groups into the Si atoms of the polymer, the UV absorption wavelength of the PMBS-co-BSP red-shifted significantly in the UV region, and a strong photoluminescence band was observed in the visible region other than the near-UV photoluminescence typical of normal polysilane. The photochemical behavior was examined both in solution and in thin film by fluorescence and UV spectroscopy. Irradiation of the PMBS-co-BSP with a low-pressure mercury lamp in solution resulted in homolytic scission of silicone-silicone bonds; the fluorescence emission intensities decreased gradually with increasing UV irradiation time and the maximum emission wavelength blue-shifted significantly. Irradiation of thin solid films of the PMBS-co-BSP in air led to the formation of photoproducts containing Si-OH and Si-O-Si groups. The PMBS-co-BSP began to weigh less at about 300 degrees C and the weight loss of the polymer at 700 degrees C was calculated to be 75% of the initial weight in N-2. (C) 2006 Society of Chemical Industry.