Copolymer

Article By:

Coote, Michelle L. Research School of Chemistry, Australian National University, Canberra, Australia.

Last reviewed:January 2020

DOI:https://doi.org/10.1036/1097-8542.160850

A macromolecule in which two or more types of monomer are incorporated into the polymer chain. This contrasts with a homopolymer, which consists of only one type of monomer. Copolymerization offers the ability to alter the properties of a homopolymer by introducing an appropriately chosen second repeating unit, or to combine the desirable properties of two different homopolymers in a single molecule. The properties of a copolymer depend on the nature of the monomers and their distribution in the chain. Thus, monomers A and B can polymerize randomly (ABBAABA), they can alternate (ABAB), they can form blocks (AAABBB), or one polymer can be grafted onto another polymer (Fig. 1). Copolymers can be prepared by all the known methods of polymerization, including addition polymerization of vinyl monomers (by conventional or living free-radical, anionic, cationic, or coordination catalysis), ring-opening polymerization, or condensation polymerization. Copolymers can also be formed by the chemical reaction of functional groups (usually end groups) on the constituent polymer chains. See also: Free radical; Macromolecular engineering; Polymer; Polymerization; Ring-opening polymerization

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