Dual-Cure Coatings: Spiroorthoesters as Volume-Controlling Additives in Thiol–Ene Reactions

Philipp Marx, Angelo Romano, Roland Fischer, Ignazio Roppolo, Marco Sangermano, Frank Wiesbrock

Research output: Contribution to journalArticleResearchpeer-review

6 Citations (Scopus)


Most thiol–ene systems exhibit shrinkage during cross-linking, potentially resulting in micro-cracks and delamination. Oligocyclic monomers like spiroorthoesters (SOEs), on the contrary, show expansion during the ring-opening polymerization. In this communication, a photocurable thiol–ene system composed of a trifunctional thiol, a bisfunctional allyl-bisphenol A compound, and an SOE compound bearing one olefin function shows expansion in the range from −3.07 to +1.70 vol% if the SOE content is increased from 0–30 wt%. Network formation can be accomplished under visible light if a radical as well as a cationic photoinitiator (dual-cure mechanism) and a sensitizer are used. The elasticity of the cured resin increases upon the addition of the SOE; correspondingly, the glass-transition temperature shows a (minor) decrease from 16 to 3 °C. A tailor-made combination of the allyl-bisphenol A compound (90 wt%) and the SOE (10 wt%) yields networks that are volume-neutral during curing.
Original languageEnglish
Article number1800627
Number of pages5
JournalMacromolecular materials and engineering
Issue number4
Early online date18 Jan 2019
Publication statusPublished - Apr 2019

Bibliographical note

Publisher Copyright: © 2019 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim


  • dual-cure mechanisms
  • spiroorthoesters
  • thiol–ene reactions
  • thiol–ene resins
  • UV-mediated curing
  • volumetric expansion

Cite this