Asymmetric Metal–Organic Framework-Based Mixed Matrix Membrane for Reversible Self-Assembling 3D Architecture

Abstract

Shape-transformation metal–organic framework (MOF)-based soft actuators that can quickly respond to external stimuli have been potential candidates in the areas of biomimetic soft robots, smart mechanical devices, and flexible devices. Herein, we construct a unique asymmetric mixed matrix membrane (MMM) consisting of swellable iron(III) fumarate (MIL-88A, MIL= Materials from Institute Lavoisier) on one side and methacrylate-functionalized polydimethylsiloxane (MA-PDMS) on the other side. Upon variation of the humidity environment, the asymmetric composite membrane exhibits reversible and repeatable bending behavior. Through simple graphical programming, the composite membrane obtains a self-folding ability and successfully realizes diversified predictable 3D architectures, including artificial flowers, automatic mechanical claws, and unilateral crawling devices. Moreover, the 3D architecture could be restored to a 2D plane through the desorption of MIL-88A and the thermal expansion of MA-PDMS derived from near-infrared (NIR) light and exhibit continuous motion to imitate living creatures in nature. This work will offer insight into the fabrication of programmable soft actuators, thus shining enlightenment for their potential application in bioinspired soft robots and smart mechanical devices.