We report a new core-shell microcapsule system for the visual detection of mechanical damage. The core material, 1,3,5,7-cyclooctatetraene, is a conjugated cyclic olefin and a precursor to intensely colored polyacetylene. A combination of poly(urea-formaldehyde) and polyurethane is required to effectively encapsulate the volatile core material. Increasing the outer shell wall thickness and including a core-side prepolymer improves the thermal stability and free-flowing nature of these capsules, which tend to leach and rupture with thinner shell walls. Capsules ruptured in the presence of the Grubbs-Love ruthenium catalyst show immediate color change from nearly colorless to red-orange and dark purple over time, and color change in thin films resulted from scratch damage.

Original languageEnglish (US)
Pages (from-to)4547-4551
Number of pages5
JournalACS Applied Materials and Interfaces
Issue number12
StatePublished - Dec 28 2011


  • color change
  • damage detection
  • encapsulation
  • microcapsule
  • ring-opening metathesis polymerization

ASJC Scopus subject areas

  • General Materials Science


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