Polymerizations have traditionally been classified as addition polymerizations and condensation polymerizations. However, developments in chemical methods of polymerization and syntheses of new types of polymer have meant that more than two classes of polymerization need to be defined if a clear terminology is to be achieved. Several, alternative, two-fold terminologies have been introduced ad hoc into the literature. All have serious shortcomings in terms of comprehensiveness, unambiguity and scientific correctness. The present document defines basically four categories of polymerization chain polymerization, condensative chain polymerization, polycondensation and polyaddition - which cover unambiguously all presently known types of polymerization. The definitions also allow further qualification if desired e.g. cationic chain polymerization. The present definitions are in accord with the recommended IUPAC Glossary of Terms for Physical Organic Chemistry (1983) and the IUPAC Basic Definitions of Terms Relating to Polymers (1974).
