Sensitive Mechanochromisms Based on a Polymer Bilayer Structure
【摘要】：We have designed a series of mechanochromic devices inspired by nature with the capabilities of changing transparency and "switching on/off" luminescence in response to mechanical stimuli. The key to accomplish these excellent optical properties is to control strain-induced surface engineering,that is,the longitudinal cracks opening and transverse invaginated folds. All of these devices are comprised of a rigid thin layer atop polydimethylsiloxane(PDMS) based elastomer,which can be facilely and quickly fabricated. For transparency change mechanochromism,the folds and cracks with excellent light trapping and scattering capabilities can endow high opaqueness to the originally highly transparent samples. The evolution of crack opening and fold–ridge mechanisms are captured through finite analysis that incorporates damage and cracks in the rigid thin layer. For luminescent mechanochromism,the strain-tunable cracks on the UV shield layer act as "gates" to mediate the traveling of UV light to "switch on/off" the luminescence of mechanochromism. This device exhibits a remarkably high strain responsive sensitivity,demonstrating an excellent sensing capability for detecting mechanical failure or damage. All the mechanochromisms also show outstanding durability and reversibility.