Near‐Infrared Light‐Driven Shape‐Morphing of Programmable Anisotropic Hydrogels Enabled by MXene Nanosheets

Abstract

Herein, we report near‐infrared (NIR) light‐driven shape‐morphing of programmable MXene‐containing anisotropic hydrogel actuators that are fabricated through in situ free‐radical copolymerization of a judiciously designed MXene nanomonomer with thermosensitive hydrogel network. A low electric field (few V mm−1) was found to enable a spatial distribution of MXene nanosheets and hence introduce anisotropy into the hydrogel network. Programmable anisotropic hydrogel actuators were developed by controlling ITO electrode pattern, direct‐current (DC) electric field direction and mask‐assisted photopolymerization. As a proof‐of‐concept, we demonstrate NIR light‐driven shape morphing of the MXene‐containing anisotropic hydrogel into various shapes and devise a four‐arm soft gripper that can perform distinct photomechanical functions such as grasping, lifting/lowering down and releasing an object upon sequential NIR light exposure.

Light‐Driven Self‐Oscillating Actuators with Phototactic Locomotion Based on Black Phosphorus Heterostructure

“…[7] Among various type of actuators,photoactuator owns unique features of remote actuation, no contact, concise control, and abundant sources of light energy,which is suitable as driving unit for use in untethered soft robot. [8] Fort he purpose of fabricating high-performance photoactuator,i ti sc rucial to develop new light responsive materials.I nr ecent years,t wo dimensional (2D) nanomaterials such as graphene, [9] MXene [10] and MoS 2 [11] with unique structure and excellent optical properties have been used to prepare photoactuators with outstanding actuation performance,r evealing the great potential of the new 2D materials in the next-generation highperformance photoactuators.Black phosphorus (BP) is anew class of 2D nanomaterials with unique lamellar structure, excellent properties and promising applications in energy storage, [12] catalysis, [13] sensing, [14] and biomedicine. [15] In particular,B Ph as shown anisotropic mechanical property, [16] exceptional electromechanical performance, [17] outstanding photothermal conversion capability across ab road range of wavelengths, [18] and thermal expansion feature, [19] making it ideal candidate for the fabrication of soft actuators.F or example,W ue tal.,f abricated black phosphorus based electrochemical actuator with high actuation properties, which mainly stems from the ordered lamellar structure and large redox activity of the black phosphorus for ions with smooth diffusion and flooding accommodation.…”

4D printing of MXene hydrogels for high-efficiency pseudocapacitive energy storage

“…2D MXenes with a formula of M n+1 X n T x (M is an early transition metal, X is carbon and/or nitrogen, n is an integer between 1 and 4, and T x represents surface functional groups) offer a large number of promising candidates for designing conductive 2D hydrogels owing to their large surface-area-to-volume ratios, high electrical conductivities (≥20,000 S cm -1 ), redox capable surface groups, and chemical/structural diversities [6][7][8][9][10][11] . To date, several MXene hydrogels have been developed by filtration 12 , or using metal ions 13 , graphene oxide 14 , or polymers (e.g., polyvinyl alcohol (PVA) 15 , polyacrylamide 16 , cellulose 17 , chitosan 18 , poly(acrylic acid) 19 , and poly(N-isopropylacrylamide) 20 ) as crosslinkers, and have demonstrated some success. Nevertheless, research on MXene hydrogels is still in its infancy, and serious challenges remain.…”

Oscillating light engine realized by photothermal solvent evaporation

“…Actuators can generate bending, contraction, elongation, and rotation morphing motions upon exposure to external stimuli to output mechanical energy 9 – 12 . Different types of actuators have been successfully developed, including dielectric elastomer actuators 13 , 14 , conducting polymers 15 , 16 , shape memory polymers and alloys 17 , 18 , twisted fiber artificial muscles 19 , 20 , ionic polymer composites 21 , pneumatic actuators 22 , and other inorganic materials 23 , 24 . The major application area of thin film actuator is either actuation or morphing.…”