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Basic Classification and Definitions of Polymerization Reactions

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Published/Copyright: October 29, 2025
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Chemistry International
From the journal Chemistry International Volume 47 Issue 4

This document provides recommendations addressing the long-standing dilemma of the wide variety of terms that are used to describe the two common classes of polymerization mechanisms in the scientific literature, which includes chemistry and polymer-science textbooks. It is an update of a 1994 IUPAC document on this topic and provides clarification and hierarchical structure regarding the basic classification and terminology describing polymerization reactions. The term step polymerization describes polymerizations in which growth occurs by reactions between monomer, oligomer, or polymer molecules of any length. We clearly denote here the two subclasses of step polymerization: additive step polymerization (synonym: polyaddition) and condensative step polymerization (synonym: polycondensation). The term chain polymerization describes polymerizations that proceed via a chain reaction with monomer molecules adding to active sites on polymer chains. Subclasses of chain polymerization include additive chain polymerization and condensative chain polymerization. The terms provide a logical and straightforward structure for describing the two common classes of polymerization mechanisms. Previously defined terms relevant to these two classes of polymerization reactions are also replicated in this Recommendation document.

Comments by 30 November 2025

https://iupac.org/recommendation/basic-classification-and-definitions-of-polymerization-reactions/

Published Online: 2025-10-29
Published in Print: 2025-10-01

©2025 by Walter de Gruyter Berlin/Boston

This work is licensed under the Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 International License.

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https://doi.org/10.1515/ci-2025-0423
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Articles in the same Issue

  1. Masthead - Full issue pdf
  2. Past President’s Column
  3. Chemistry at the Crossroads: Enabling Solutions for a Changing World
  4. Features
  5. IUPAC’s 2025 Top Ten Emerging Technologies in Chemistry
  6. Preventing spread of chemical weapons in an era of rapid technological change
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  8. Spotlight on IUPAC Young Observers
  9. Spotlight on IUPAC U.S. Young Observers
  10. IUPAC Wire
  11. IUPAC Launches Global Call to Action for Responsible Chemistry
  12. IUPAC Announces the 2025 Top Ten Emerging Technologies in Chemistry
  13. Actions Taken by IUPAC Council, Kuala Lumpur, Malaysia, July 2025
  14. Recognising Excellence: CCE 2026 Awards—Call for Nominations
  15. 2026 IUPAC-Richter Prize—Call for Nominations
  16. 2026 IUPAC–Soong Prize for Sustainable Chemistry—Call for Nominations
  17. 2026 IUPAC-Solvay International Award for Young Chemists—Call for Applicants
  18. Systems Thinking in Chemistry Education—Call for Papers
  19. Special issue IYQ in PAC
  20. In Memoriam
  21. Project Place
  22. Terminology for Dynamic Polymer Networks and Hydrogels
  23. Systems Thinking, Sustainability and Chemical Industry
  24. Small-Scale Chemistry Initiative in India
  25. Making an imPACt
  26. Definitions and preferred symbols for mass diffusion coefficients in multicomponent fluid mixtures including electrolytes (IUPAC Technical Report)
  27. IUPAC/CITAC guide: interlaboratory comparison of categorical characteristics of a substance, material, or object (IUPAC Technical Report)
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  29. IUPAC Provisional Recommendations
  30. Basic Classification and Definitions of Polymerization Reactions
  31. Conference Call
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  34. Can the “Right to Science” Restore Public Trust?
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  37. Science at a Crossroads: Restoring Integrity and Public Trust
  38. Science: A Truth Worth Defending
  39. Building Trust in Science: A Two-Way Commitment
  40. Science Under Siege: Confronting the Hydra’s Many Heads
  41. Sustainable Practices for Promoting Diversity in Chemistry
  42. Green Chemistry for a Sustainable Future
  43. Advancing Scientific Terminology & Standards for the Digital Era—DUST Conference 2025
  44. Stockholm Declaration on Chemistry for the Future
  45. Mark Your Calendar
  46. Index
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