Thermal decomposition of poly(styrene) in the presence of a hydrogen atom transfer agent

General-purpose poly(styrene) is conventionally prepared using radical techniques in which termination of polymerization occurs through radical coupling to form a head-to-head unit. Previous evidence has shown that the bond linking the head-to-head components can undergo homolysis under thermal stress. Styrene monomer is generated from the rapid depolymerization of the macroradicals generated to release styrene monomer. Poly(styrene) containing no head-to-head units, on the other hand, does not undergo similar decomposition. Furthermore, the presence of polymer additives such as a hydrogen transfer agent that can effectively trap the macroradicals generated by chain scission should inhibit chain unzipping to form monomer. A direct comparison of the stability of the polymer in the presence and absence of a hydrogen atom transfer agent is readily available by thermogravimetric techniques.