Expanding Monomers as Anti-Shrinkage Additives

Philipp Marx, Frank Wiesbrock

Research output: Contribution to journalReview articlepeer-review

4 Citations (Scopus)


Commonly, volumetric shrinkage occurs during polymerizations due to the shortening of the equilibrium Van der Waals distance of two molecules to the length of a (significantly shorter) covalent bond. This volumetric shrinkage can have severe influence on the materials’ properties. One strategy to overcome this volumetric shrinkage is the use of expanding monomers that show volumetric expansion during polymerization reactions. Such monomers exhibit cyclic or even oligo-cyclic structural motifs with a correspondingly dense atomic packing. During the ring-opening reaction of such monomers, linear structures with atomic packing of lower density are formed, which results in volumetric expansion or at least reduced volumetric shrinkage. This review provides a concise overview of expanding monomers with a focus on the elucidation of structure-property relationships. Preceded by a brief introduction of measuring techniques for the quantification of volumetric changes, the most prominent classes of expanding monomers will be presented and discussed, namely cycloalkanes and cycloalkenes, oxacycles, benzoxazines, as well as thiocyclic com-pounds. Spiroorthoesters, spiroorthocarbonates, cyclic carbonates, and benzoxazines are particularly highlighted.
Original languageEnglish
Article number806
Number of pages32
Issue number5
Publication statusPublished - 6 Mar 2021

Bibliographical note

Publisher Copyright: © 2021 by the authors. Licensee MDPI, Basel, Switzerland.


  • Cationic ring-opening polymerization
  • Expanding monomer
  • Radical ring-opening polymerization
  • Volumetric expansion
  • Volumetric shrinkage

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