Photo-Induced Mechanical Cloaking of Diarylethene-Crosslinked Microgels.

The serial connection of multiple stimuli-responses in polymer architectures enables the logically conjunctive gating of functional material processes on demand. Here, a photoswitchable diarylethene (DAE) acts as crosslinker in poly(N-vinylcaprolactam) (PVCL) microgels and allows the light-induced shift of the volume phase transition temperature (VPTT). While swollen microgels below the VPTT are susceptible to force and undergo breakage-aggregation processes, collapsed microgels above the VPTT stay intact in mechanical fields induced by ultrasonication. Within a VPTT shift regime, photoswitching of the DAE transfers microgels from the swollen to the collapsed state and thereby gates their response to force as demonstrated on the light-gated activation of an embedded fluorogenic mechanophore. This photo-induced mechanical cloaking system operates on the polymer topology level and is thereby principally universally applicable. This article is protected by copyright. All rights reserved.