A Density Functional Theory Study of Secondary Reactions in n-Butyl Acrylate Free Radical Polymerization

In this work, secondary reactions involved in the free radical polymerization of butyl acrylate are investigated using quantum chemistry. First, various backbiting reactions are studied by adopting a simplified molecular model suitable for treating long polymer chains. The predicted reaction kinetics suggest the possibility of a radical migration along the poly(butyl acrylate) (PBA) chain as a consequence of subsequent j:j+4 hydrogen abstractions, which are characterized by a low activation energy. Moreover, branching propagation and -scission reactions originating from mid-chain radicals are investigated using a complete PBA model composed of five monomer units. The reaction kinetics involving short-branch radicals are also examined, and a novel backbiting step leading to the formation of short branches is proposed.