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 journalArticlepeer-review


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
Publication statusPublished - 2019


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

ASJC Scopus subject areas

  • Materials Chemistry
  • Chemical Engineering(all)
  • Polymers and Plastics
  • Organic Chemistry

Fields of Expertise

  • Advanced Materials Science


  • NAWI Graz


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