A
chain reaction in which the growth of a polymer
chain proceeds exclusively by reaction(s) between
monomer(s) and reactive site(s) on the polymer chain with regeneration of the reactive site(s)
at the end of each growth step.
Notes:
-
A chain polymerization consists of initiation and propagation reactions, and may also include termination and chain transfer reactions.
-
The adjective 'chain' in 'chain polymerization' denotes a 'chain reaction' rather than a 'polymer chain'.
- Propagation in chain polymerization usually occurs without the formation of small molecules. However, cases exist where
a low-molar-mass by-product is formed, as in the polymerization of oxazolidine-2,5-diones derived from amino acids (commonly termed amino-acid N-carboxy anhydrides). When a low-molar-mass by-product is formed, the adjective 'condensative' is recommended to give the term condensative chain polymerization
-
The growth steps are expressed by:
where
denotes the growing chain of degree of polymerization
,
a monomer and
a low-molar-mass by-product formed in the case of condensative chain polymerization.
-
The term 'chain polymerization' may be qualified further, if necessary, to specify the type of chemical reactions
involved in the growth step, e.g. ring-opening chain polymerization, cationic chain polymerization.
-
There exist, exceptionally, some polymerizations that proceed via chain reactions that, according to the definition, are not chain polymerizations.
For example, the polymerization:
proceeds via a radical chain reaction with intermolecular transfer of the radical centre. The growth step, however, involves reactions between
molecules of all degrees of polymerization and, hence, the polymerization is classified as a polyaddition. If required, the classification can be made more precise and the polymerization described as a chain-reaction polyaddition.
Source:
PAC, 1996, 68, 2287
(Glossary of basic terms in polymer science (IUPAC Recommendations 1996)) on page 2306
InChI=1/2C2H3.Y/c2*1-2;/h2*1H,2H2;
KNFDAYSMHRAUJS-UHFFFAOYAD
Cite as:
IUPAC. Compendium of Chemical Terminology, 2nd ed. (the "Gold Book"). Compiled by
A. D. McNaught and A. Wilkinson. Blackwell Scientific Publications, Oxford (1997).
XML on-line corrected version: http://goldbook.iupac.org (2006-) created by M. Nic,
J. Jirat, B. Kosata; updates compiled by A. Jenkins. ISBN 0-9678550-9-8.
https://doi.org/10.1351/goldbook.
