Photocrosslinking Patterning of Single-Layered Polymer Actuators for Controllable Motility and Automatic Devices

Abstract

Shape-programmed deformation of soft polymer films is essential for applications in robotics, self-adaptive devices, and sensors. In comparison to bilayer polymer actuators, the challenge remains to manipulate single-layered soft actuators for rapid, reversible, and shape-programmed deformations in response to external stimuli owing to their homogeneous composite structures. Herein, this work reports a soft polymer film actuator that has a single-layered structure, yet demonstrates the shape-programmed motility. The actuator is composed of polyvinylidene fluoride film as a matrix and patterned by photocrosslinking of acrylamide and N′,N′-methylenebisacrylamide, which generates soft–hard alternating segments in the structure. As it is exposed to acetone vapors, the soft–hard structures lead to an unequal response that results in the shape-programmed deformation. The actuator is elastic (strain: 160%) and tough (stress: 40 MPa) and can maintain its rapid, reversible, and shape-programmed motions for a few hours, even longer. The soft–hard structure enables the film actuator (3.5 mg) to give a contracting stress of 4 MPa that is used in an automatic device able to lift a cargo of 5.09 g, ∼1453 times heavier than the film itself. The power output reaches 474 J kg–1, ∼100 times higher than the reported soft actuators. This simple application indicates a potential for the soft actuator used in acetone vapor sensing devices.

Highly Tunable Piezoelectricity of Flexible Nanogenerators Based on 3D Porously Architectured Membranes for Versatile Energy Harvesting and Self-Powered Multistimulus Sensing

“…As displayed in Figure b and Video S3, when exposed to the volatile acetone vapor, the representative PHFe-5 membrane bends quickly into a circle within 2 s, while it returns to the initial flat state after removing the acetone stimuli. The observed acetone vapor-responsive actuation is attributed to the noncovalent interactions between PVDF-HFP chains and acetone vapor molecules. , Understandably, when the porous PHFe membranes are positioned above the acetone solvent, the evaporated molecules diffuse rapidly into the membranes from the lower surface to the upper surface. Due to the difference in the spatial absorbance rate across the thickness of membranes, an asymmetric volume expansion rate occurs such that the membrane bends to the upper surface side.…”

Interfacial Fabrication of CNTs/PVDF Bilayer Actuator with Fast Responses to the Light and Organic Solvent Vapor Stimuli

“…As soon as exposure to the acetone vapor, one finger-shaped membrane bends rapidly within 0.19 s. When the acetone vapor is switched off, the bent finger returns to the original straight state in 1.24 s. One reversible bending/ relaxing cycle can be finished within 1.43 s. This bending and relaxing speed of prepared CNT/PVDF is much faster than the previous PVDF-based actuator. [7,22,[40][41][42][43][44][45][46][47] Compared with other carbon-based PVDF bilayer without porous structures, [11,48] the responding speed of prepared CNT/PVDF is also much faster. The porous structures can accelerate the internal mass transport and give rise to a rapid responsiveness.…”

A New Strategy of Discretionarily Reconfigurable Actuators Based on Self‐Healing Elastomers for Diverse Soft Robots

“…[ 1,10,11 ] Anisotropic hybrid systems of smart materials are critical for the development of actuators. [ 12–14 ] The methods that are currently available for the fabrication of anisotropic structures include one‐step method, [ 15,16 ] layer‐by‐layer polymerization, [ 17–19 ] 3D printing, [ 20 ] photolithography, [ 21 ] and ion printing. [ 22,23 ] These actuators contain crosslinking structures, and chemical crosslinking usually fixes the anisotropic structures of soft actuators and stabilizes their actuation performance.…”