Strong, Self‐Healable, and Recyclable Visible‐Light‐Responsive Hydrogel Actuators

Abstract

The most pressing challenges for light‐driven hydrogel actuators include reliance on UV light, slow response, poor mechanical properties, and limited functionalities. Now, a supramolecular design strategy is used to address these issues. Key is the use of a benzylimine‐functionalized anthracene group, which red‐shifts the absorption into the visible region and also stabilizes the supramolecular network through π–π interactions. Acid–ether hydrogen bonds are incorporated for energy dissipation under mechanical deformation and maintaining hydrophilicity of the network. This double‐crosslinked supramolecular hydrogel developed via a simple synthesis exhibits a unique combination of high strength, rapid self‐healing, and fast visible‐light‐driven shape morphing both in the wet and dry state. As all of the interactions are dynamic, the design enables the structures to be recycled and reprogrammed into different 3D objects.

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

“…The most common strategy alters molecular structures in actuators, and involves the use of reversible reactions such as rearrangement of liquid crystal mesogenic units, [ 25,28,29,31–34 ] trans‐cis isomerization of azobenzene, [ 35 ] and reversible crosslinking and decrosslinking. [ 36–39 ] This strategy modifies the anisotropic structures in actuators to achieve multi‐mode actuation. External stimuli such as heating and patterned light illumination are required to promote these reversible reactions that change the anisotropic structures in actuators.…”

Dynamic, multimodal hydrogel actuators using porphyrin-based visible light photoredox catalysis in a thermoresponsive polymer network

“…However, for potential biomedical applications, longer wavelengths of light in the near-IR optical window (650-950 nm) are required to penetrate human tissue. 49,50 Along these lines, many examples have been reported involving the fabrication of functional so materials that are programmed to respond to red [51][52][53] and/or NIR light. [35][36][37]41 But, to the best of our knowledge, none of the aforementioned materials and related designs are capable of operating using multiple wavelengths of light, whilst also simultaneously possessing thermoresponsive behavior.…”

Mechanically Stable Dynamic Urea Bond‐Based Crosslinked Polymer Blend with Tunable Self‐Healable and Physical Properties

“…The self‐healing mechanism of self‐healing polymers is mostly based on the dynamically reversible bond (e.g., hydrogen bonding, [ 4–7 ] π–π interactions, [ 8 ] metal–ligand interactions, [ 9,10 ] guest–host interactions, [ 11 ] Diels–Alder chemistry, [ 12,13 ] boronic ester, [ 14,15 ] diselenide, [ 16 ] diarylbibenzofuranone, [ 17 ] disulfide, [ 18,19 ] and alkoxyamine [ 20 ] ), shape memory effect‐assisted self‐healing, [ 21,22 ] and the enhanced movement of polymeric chain. Of note, the polymeric chain mobility is a key factor to facilitate dynamic bond reversibility and self‐healing.…”