Functionalization of planar and curved glass surfaces with spiropyran (SP) molecules and localized UV-induced activation of the mechanophore are demonstrated. Fluorescence spectra of UV-irradiated SP-functionalized surfaces reveal that increases in surface roughness or curvature produce more efficient conversion of the mechanophore to the open merocyanine (MC) form. Further, force-induced activation of the mechanophore is achieved at curved glass-polymer interfaces and not planar interfaces. Minimal fluorescence signal from UV-irradiated SP-functionalized planar glass surfaces precluded mechanical activation testing. Curved glass-polymer interfaces are prepared by SP functionalization of E-glass fibers, which are subsequently embedded in a poly(methyl methacrylate) (PMMA) matrix. Mechanical activation is induced through shear loading by a single fiber microbond testing protocol. In situ detection of SP activation at the interface is monitored by fluorescence spectroscopy. The fluorescence increase during interfacial testing suggests that attachment of the interfacial SP molecule to both fiber surface and polymer matrix is present and able to achieve significant activation of SP at the fiber-polymer matrix interface. Unlike previous studies for bulk polymers, SP activation is detected at relatively low levels of applied shear stress. By linking SP at the glass-polymer interface and transferring load directly to that interface, a more efficient mechanism for eliciting the SP response is achieved.
|Number of pages||8|
|State||Published - Jun 2 2020|
Bibliographical noteFunding Information:
The authors gratefully acknowledge the Beckman Institute for Advanced Science and Technology for their assistance in this work. Experiments were carried out in the Beckman Institute Imaging Technology Group, University of Illinois at Urbana—Champaign. The authors also thank Nicholas Munaretto for assistance with SP synthesis and Amanda Jones for helpful insight into single fiber testing. Funding was provided by the ARO MURI W911NF-07-0409 and the National Science Foundation, CMMI 11-61517.
© 2020 American Chemical Society.
ASJC Scopus subject areas
- Materials Science (all)
- Condensed Matter Physics
- Surfaces and Interfaces