A solvent driven dual responsive actuator based on MOF/polymer composite

The dual-responsive actuator which response to external stimulus with deformation and discoloration simultaneously gained considerable attention for their application such as soft robot. Inspired by the soft MOF (Metal-Organic framework)/polymer solvent driven actuator based on flexible MOF which can expand/contract with the gain and loss of solvent molecules, and also the structural color films with inverted opal structure, a monolayer solvent driven dual-responsive actuator based on MOF/polymer composite, namely MIL-88A/CB(carbon black)/PVDF, has been successfully prepared through the casting and etching method. The MIL-88A/CB/PVDF film can respond to the change of ambient solvent atmosphere with the whole or part of the composite film exhibiting a synergistic coupling of the surface color change and the out-of-plane motion under the driven of the methanol vapor. The bending deformation of 730° can be quickly achieved in about 1.66 s and the color change covers a wide range with three high saturation color (red, green and blue) which can be observed with different view angles. In addition, some simple devices including smart flower, inchworm walker, and visual gas sensor were designed based on this material. This work is the first example which apply MOF to solvent driven dual response materials with simultaneous deformation and discoloration, which opens up a new application field for MOF, and also provides a new perspective for the preparation of smart materials. [Display omitted] •A composite film with synchronous deformation-discoloration dual response to methanol.•The flexible MOF in the film enables a fast deformation response to methanol atmosphere.•The synchronous discoloration comes from surface inverted opal structure by etching.•Several smart devices were designed based on the dual-response of the composite film.