Catalysis in Polymerization

Hardly a single polymerization process exists in which certain accelerating, regulating, and modifying ingredients are not used with great advantage even though they might be present only in very small quantities. In the early years of the art, when there did not yet exist a well-founded understanding of the mechanism of polymerization processes, the action of these ingredients and additives so much resembled the phenomenon of normal catalysis that the name catalysts was used for them. Today, in the clarifying hindsight of a rather well-developed theory of polymerization reactions, it is evident that in most cases the role of these substances during the formation of macromolecules does not fall in the domain of the classical definitions of the words catalysis and catalyst.