Intramolecular chain termination by ring formation determining features of radical polymerization of arylacetylenes

Kinetics of thermal polymerization of phenyl- and β-deuterophenylacetylene were studied in bulk at 393–423°K. The constancy of the reactivity of a growing macroradical with degrees of polymerization f⩾3–4 in the case of thermal and f⩾6 in the case of initiated process, as well as low M and narrow MD of products of radical polymerization of arylacetylenes prove that chain termination is by intramolecular ring formation of the propagating end with the formation of a cyclohexadienyl radical, stabilized by intra- or intermolecular transfer of the hydrogen atom at a stage where it does not limit the rate of polymerization.