γ radiolysis of neat 2-phenylheptamethyltrisilane as a model of polysilastyrene

2-Phenylheptamethyltrisilane as a model compound of polysilastyrene was irradiated at a high dose (1440 kGy) of γ-rays without any additive. The trisilane was found to be resistant to γ-rays, while it gave small amounts of Me₆Si₂, Me₃SiSiMe₂Ph, Me₃SiH, Me₃SiSiHMePh and (Me₃Si)₂ SiMeC₆H₄SiMe₃. These products can be interpreted as being due to a chain contraction of the trisilane with the extrusion of methylphenylsilylene, a methyl migration with the extrusion of dimethylsilylene, a scission of an Si–Si bond due to an attack by hydrogen atoms, and a substitution of a hydrogen atom on the phenyl group by a trimethylsilyl radical. The same reactions, except the chain contraction, are observed in the cases of pentamethylphenyldisilane and 1,2-diphenyltetramethyldisilane. On the basis of the data obtained, the chemical behavior of polysilastyrene during the irradiation is discussed.