Reconsidering terms for mechanisms of polymer growth: the “step-growth” and “chain-growth” dilemma


The terms “step-growth polymerization” and “chain-growth polymerization” are used widely in both written and oral communications to describe the two main mechanisms of polymer growth. As members of the Subcommittee on Polymer Terminology (SPT) in the Polymer Division of the International Union of Pure and Applied Chemistry (IUPAC), we are concerned that these terms are confusing because they do not describe the fundamental differences in the growth of polymers by these methods. For example, both polymerization methods are comprised of a series of steps, and both produce polymer chains. In an effort to recommend comprehensive terms, a 1994 IUPAC Recommendation from the then version of SPT suggested polycondensation and polyaddition as terms for the two variants of “step-growth polymerization”, and similarly chain polymerization and condensative chain polymerization for the two variants of “chain-growth polymerization”. However, these terms also have shortcomings. Adding to the confusion, we have identified a wide variety of other terms that are used in textbooks for describing these basic methods of synthesizing polymers from monomers. Beyond these issues with “step-growth” and “chain-growth”, synthesis of polymers one monomer unit at a time presents a related dilemma in that this synthetic strategy is wholly encompassed by neither of the traditional growth mechanisms. One component of the mission of IUPAC is to develop tools for the clear communication of chemical knowledge around the world, of which recommending definitions for terms is an important element. Here we do not endorse specific terms or recommend new ones; instead, we aim to convey our concerns with the basic terms typically used for classifying methods of polymer synthesis, and in this context we welcome dialogue from the broader polymer community in a bid to resolve these issues.

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Divisions: College of Engineering & Physical Sciences > Aston Institute of Materials Research (AIMR)
College of Engineering & Physical Sciences > Aston Polymer Research Group
Additional Information: This article is licensed under a Creative Commons Attribution 3.0 Unported Licence Funding Information: We acknowledge IUPAC for support of this work through project 2019-027-1-400.
Uncontrolled Keywords: Bioengineering,Biochemistry,Organic Chemistry,Polymers and Plastics
Publication ISSN: 1759-9962
Last Modified: 15 Jul 2024 08:19
Date Deposited: 21 Apr 2022 15:25
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PURE Output Type: Letter
Published Date: 2022-04
Published Online Date: 2022-04-05
Accepted Date: 2022-03-15
Authors: Chan, Chin Han
Chen, Jiun-Tai
Farrell, Wesley S.
Fellows, Christopher M.
Keddie, Daniel J.
Luscombe, Christine K.
Matson, John B.
Merna, Jan
Moad, Graeme
Russell, Gregory T.
Théato, Patrick
Topham, Paul D. (ORCID Profile 0000-0003-4152-6976)
Sosa Vargas, Lydia



Version: Published Version

License: Creative Commons Attribution

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