title: Visual indication of mechanical damage using core-shell microcapsules.
abstract: 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.
authors: Beckman Institute for Advanced Science & Technology, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801, USA.
authors: Susan A
authors: SA
authors: Odom
authors: Aaron C
authors: AC
authors: Jackson
authors: Alex M
authors: AM
authors: Prokup
authors: Sarut
authors: S
authors: Chayanupatkul
authors: Nancy R
authors: NR
authors: Sottos
authors: Scott R
authors: SR
authors: White
authors: Jeffrey S
authors: JS
authors: Moore