Programmable Self‐Assembling 3D Architectures Generated by Patterning of Swellable MOF‐Based Composite Films

Abstract

The integration of swellable MOFs into polymeric composite films is a straightforward strategy to develop soft materials which undergo reversible shape transformations derived from the intrinsic flexibility of MOF crystals. However, a crucial step towards their practical application relies in the ability to attain specific and programmable actuation, which enables the design of self-shaping objects on demand. Herein, a chemical etching method is demonstrated for the fabrication of patterned composite films showing tunable self-folding response, predictable and reversible 2D-to-3D shape transformations triggered by water adsorption/desorption. These films are fabricated by selective removal of swellable MOF crystals allowing the control over their spatial distribution within the polymeric film. Upon exposure to moisture, various programmable 3D architectures that include a mechanical gripper, a lift and a unidirectional walking device are generated. Remarkably, these 2D-to-3D shape transformations can be reversed by light-induced desorption. The reported strategy offers a platform for fabricating flexible MOF-based autonomous soft mechanical devices with functionalities for micromanipulation, automation and robotics.

Asymmetric elastoplasticity of stacked graphene assembly actualizes programmable untethered soft robotics

“…Recently, a variety of flexible morphing systems have been developed with configurable soft materials by taking the advantage of various mechanisms such as asymmetric thermal expansion 5,6 , liquid crystalline transitions 7,8 , phase transitions [9][10][11][12] , and anisotropic swelling [13][14][15][16][17][18][19][20][21] , etc. To achieve shape programming and customization, numerous efforts have been made by applying specific chemical structures through a variety of polymeric materials including shape memory polymers (SMPs) [22][23][24][25] , vitrimer 26 , hydrogel [27][28][29] , organogel 30 .…”

Actuation and locomotion driven by moisture in paper made with natural pollen

“…Consider, for example, the case of smart actuators wherein most of the key components are derived from graphenebased materials or synthetic polymers (26)(27)(28)(29)(30). Given the common limitations associated with these materials in terms of their relatively high cost, strict reaction control, and issues with environmental sustainability, the quest for more cost-effective materials from natural and renewable sources has accelerated (31)(32)(33)(34). Although natural materials such as agarose (24,32,35) and cellulose (11,(36)(37)(38) are used in a number of applications, they must be extracted and refined from raw resources at a considerable energy cost.…”

Laser‐Induced Graphene for Electrothermally Controlled, Mechanically Guided, 3D Assembly and Human–Soft Actuators Interaction

“…Currently, many promising actuating materials, that can potentially trigger 2D‐to‐3D shape transformations, are available, such as dielectric elastomers, shape‐memory polymers, polymer composites, and hydrogels, which can be driven by electricity, heat, light, magnetism, solvent, humidity, and/or multi‐stimuli. [ 25–39 ] For example, compressive bulking guided, on‐demand 3D assembly has been recently achieved by using dielectric elastomers [ 38 ] and shape memory polymers [ 39 ] as the assembly substrates. However, these two strategies have some limitations in terms of high operation voltages (thousands of volts) and poor reversibility and cyclability, respectively.…”