THERMAL-DEGRADATION OF POLY(METHYL-N-HEXYLSILYLENE)

Thermal degradation of poly(methyl-n-hexylsilane) in the solid state i n absence of oxygen reveals formation of a cyclic pentamer between 150 and 250 degrees C. Polymer is gradually degraded to an intermediate m olecular weight distribution. The weight average of this new distribut ion is not only temperature-dependent, but is also a function of visco sity of the polymer and nature of chain ends. As no insolubles or Si-H groups are formed, the degradation mechanism is most likely a back-bi ting mechanism induced by active chain ends such as silyl anions or Si -Cl rather than a homolytic cleavage of the main chain. A concurrent i ntramolecular rearrangement reaction is also proposed. Moreover, this study proposes an explanation to the trimodal molecular weight distrib ution obtained by the Wurtz coupling of dichlorosilanes with molten so dium in refluxing toluene. (C) 1995 John Wiley and Sons, Inc.