Photoreaction of alkoxypolysilanes

The photoreaction of network ethoxypolysilanes ((MeSi)(n)[Me(EtO)Si](m)) using low pressure mercury lamps was investigated in the presence and in the absence of oxygen, and was compared with that of poly(hexylsilyne) and poly(dihexylsilylene). The photoreaction of the ethoxypolysilanes in the presence of oxygen led to their photooxidation, and resulted in a decreased molecular weight and the disappearance of ultraviolet absorption over 300 nm. The molecular weight of the ethoxypolysilanes was more slowly reduced than that of poly(hexylsilyne). On the other hand, photolysis of the ethoxypolysilanes under an inert atmosphere caused an increase in molecular weight, though similar photolysis of the alkylpolysilanes showed a molecular weight decrease. These results could be explained by the influence of the ethoxysilyl groups in the polysilanes. The decomposition of polymer chains would be depressed by the reaction of the alkoxysilyl groups with silanols produced from photooxidation and the insertion reaction of silylenes into Si-OEt bonds. (C) 1997 Elsevier Science Ltd.