Application of Molecular Orbital Theory to Vinyl Polymerization

Abstract

A chain polymerization may be said to occur when a monomer adds to some reactive species, generating another active compound, which then repetitively adds many more molecules of monomer. There exist hundreds of vinyl monomers which can be polymerized by either ionic or free-radical mechanisms, and therefore the experimental studies of vinyl chain polymerization have been very diverse in their character. All such studies, however, have had the common feature of seeking to determine the reactivity of the monomer involved in the polymerization. Strictly speaking, this reactivity includes the initiation, propagation, and termination reactions, as well as chain transfer and any side reactions, but in many cases the term “reactivity” is applied only to the propagation reaction, particularly in copolymerization studies. The latter practice will be followed in this review, which primarily deals with the molecular orbital (MO) calculation of monomer reactivity in propagation reactions, but also includes some discussion of other reactions in chain polymerization.