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

Abstract

Open AccessCCS ChemistryRESEARCH ARTICLE1 Jan 2022Protective Coating with Crystalline Shells to Fabricate Dual-Stimuli Responsive Actuators Peixin Xu, Qi Yu, Yao Chen, Peng Cheng and Zhenjie Zhang Peixin Xu State Key Laboratory of Medicinal Chemical Biology, College of Chemistry, Nankai University, Tianjin 300071 , Qi Yu State Key Laboratory of Medicinal Chemical Biology, College of Chemistry, Nankai University, Tianjin 300071 Shandong Provincial Key Laboratory of Fine Chemicals, School of Chemistry and Pharmaceutical Engineering, Qilu University of Technology, Jinan 250353 , Yao Chen State Key Laboratory of Medicinal Chemical Biology, College of Chemistry, Nankai University, Tianjin 300071 , Peng Cheng State Key Laboratory of Medicinal Chemical Biology, College of Chemistry, Nankai University, Tianjin 300071 Key Laboratory of Advanced Energy Materials Chemistry, Ministry of Education, Nankai University, Tianjin 300071 and Zhenjie Zhang *Corresponding author: E-mail Address: [email protected] State Key Laboratory of Medicinal Chemical Biology, College of Chemistry, Nankai University, Tianjin 300071 Key Laboratory of Advanced Energy Materials Chemistry, Ministry of Education, Nankai University, Tianjin 300071 https://doi.org/10.31635/ccschem.021.202000663 SectionsSupplemental MaterialAboutAbstractPDF ToolsAdd to favoritesDownload CitationsTrack Citations ShareFacebookTwitterLinked InEmail 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. Download figure Download PowerPoint Introduction Mechanically responsive smart materials that can convert chemical energy into mechanical movement have been attracting considerable interest in a wide range of advanced applications such as robotics, actuators, and sensors.1–8 This energy transformation can be achieved by the reversible deformation of materials (e.g., contraction, expansion, rotation, bending, twisting, and curling) under external stimuli such as electrical fields, temperature, light, pH, vapor, and pressure.9–12 At present, most mechanically responsive materials are based on polymeric materials, including organic polymers, hydrogels, and liquid crystal elastomers,13–17 while relatively less focus has been placed on molecular crystals that possess precisely determined structures with ordered molecular packing. Molecular crystals exhibit many advantages as smart materials that can surpass traditional polymeric materials such as rapid response, faster relaxation recovery, and a higher Young's modulus.9,18 Nevertheless, the small size, brittleness, and poor mechanical properties make molecular crystals unsuitable for sufficient energy conversion into useful motion (work) or macroscale device fabrication. To address these and other challenges, Lan and Chen19 and Yu et al.20 have developed facile strategies to fabricate macroscale hybrid materials by combining nano- or microsca