Polysilane High Polymers: Mechanism of Photodegradation

Photolysis of the high polymer (n-C6H13, MeSi)nin CCL4leads to the formation of C2CL6, indicating that the photodegradative pathway of these polymers includes the formation of silyl radicals. Photolysis of alkyl-substituted polysilane polymers, (R1R2Si)n (R1= n-hexyl, R2 = Me; R1 = R2 = n-hexyl; R1= cyclohexyl, R2 = Me), at 254 nm in the presence of triethylsilane gives two major products, Et3Si-R1R2SiH and HR1R2Si-R1R2SiH. Photolysis of (n-C6H13MeSi)„ in the presence of ROH (R = Me; R = n-Pr) gives four major products, n-C6H13(Me)Si(OH)H, H(n-C6H13)(Me)Si-(n-C6H13)(Me)SiH, H(n-C6H13)(Me)Si-(n-C6H13)(Me)SiOR, and (RO)(n-C6HI3)(Me)Si-(n-C6H13)(Me)SiOR. To explain these results, a photolytic cascade mechanism that involves both the extrusion of silylene units and the formation of silyl radical terminated polymer fragments is proposed. The photochemistry of phenyl-substituted polysilane polymers was examined and found to be considerably more complex than the photochemistry of the alkyl-substituted polymers. © 1985, American Chemical Society. All rights reserved.