Interfacial Mechanophore Activation Using Laser-Induced Stress Waves
A new methodology is developed to activate and characterize mechanochemical transformations at a solid interface. Maleimide–anthracene mechanophores covalently anchored at a fused silica–polymer interface are activated using laser-induced stress waves. Spallation-induced mechanophore activation is observed above a threshold activation stress of 149 MPa. The retro [4+2] cycloaddition reaction is confirmed by fluorescence microscopy, XPS, and ToF-SIMS measurements. Control experiments with specimens in which the mechanophore is not covalently attached to the polymer layer exhibit no activation. In contrast to activation in solution or bulk polymers, whereby a proportional increase in mechanophore activity is observed with applied stress, interfacial activation occurs collectively with spallation of the polymer film.
Additional Information© 2018 American Chemical Society. Received: February 5, 2018; Published: March 29, 2018. This work was supported in part by the National Science Foundation (Grant No. DMR 13-07354) and the Office of Naval Research (Grant No. 0014-12-1-0828). M.J.R. gratefully acknowledges the Arnold and Mabel Beckman Foundation for a Beckman Institute Postdoctoral Fellowship. The authors declare no competing financial interest.
Supplemental Material - ja8b01427_si_001.pdf