A @[email protected] in which the growth of a polymer @[email protected] proceeds exclusively by reaction(s) between @[email protected] and reactive site(s) on the polymer chain with regeneration of the reactive site(s) at the end of each growth step.
  1. A chain @[email protected] consists of @[email protected] and @[email protected] reactions, and may also include @[email protected] and @[email protected] reactions.
  2. The adjective 'chain' in 'chain @[email protected]' denotes a '@[email protected]' rather than a 'polymer chain'.
  3. @[email protected] in chain @[email protected] usually occurs without the formation of small molecules. However, cases exist where a low-molar-mass by-product is formed, as in the @[email protected] of oxazolidine-2,5-diones derived from amino acids (commonly termed amino-acid N-carboxy @[email protected]). When a low-molar-mass by-product is formed, the adjective 'condensative' is recommended to give the term condensative chain polymerization
  4. The growth steps are expressed by: \[\text{P}_{x} + \text{M}\rightarrow \text{P}_{x + 1}\hspace{5pt}(+\ \text{L}) \hspace{35pt} \{x\}\in \{1,2,\ \dots \infty\};\] where \(P_{x}\) denotes the growing chain of @[email protected] \(x\), \(M\) a @[email protected] and \(L\) a low-molar-mass by-product formed in the case of condensative chain polymerization.
  5. The term 'chain @[email protected]' may be qualified further, if necessary, to specify the type of chemical reactions involved in the growth step, e.g. ring-opening chain @[email protected], cationic chain @[email protected]
  6. There exist, exceptionally, some polymerizations that proceed via chain reactions that, according to the definition, are not chain polymerizations. For example, the @[email protected]:
    proceeds via a radical @[email protected] with @[email protected] transfer of the radical centre. The growth step, however, involves reactions between molecules of all degrees of @[email protected] and, hence, the @[email protected] is classified as a @[email protected] If required, the classification can be made more precise and the @[email protected] described as a chain-reaction @[email protected]
PAC, 1996, 68, 2287. (Glossary of basic terms in polymer science (IUPAC Recommendations 1996)) on page 2306 [Terms] [Paper]