Protective Coating with Crystalline Shells to Fabricate Dual-Stimuli Responsive Actuators

Abstract

The hybridization of mechanically responsive molecular crystals with polymers has proven to be an efficient approach to fabricate smart hybrid materials that can produce multiple motions upon external stimulus actuation. However, this fabrication approach occasionally displays limitations due to the solubility or poor dispersibility of molecular crystals in the polymer matrix solution. To address these challenges, we have created a facile and versatile strategy to use metal-organic frameworks (MOFs) as a protective coating against external perturbations while also improving the dispersibility of molecular crystals. As such, a series of hybrid smart materials with reversible photomechanical performance were successfully fabricated. Notably, the afforded smart materials can combine the photoresponsive properties of mechanically responsive molecular crystals with the vapor-responsive properties of certain polymers in one system, thereby obtaining dual-stimuli responsive actuators that can perform complicated motions (e.g., crawling). These results pave the way for the fabrication of multistimuli responsive smart materials and broaden the applicable scope of MOFs.