Actuating Supramolecular Shape Memorized Hydrogel Toward Programmable Shape Deformation

Abstract

Inspired by nature, diverse biomimetic hydrogel actuators are fabricated and become one of the most essential components of bionics research. Usually, the anisotropic structure of a hydrogel actuator is generated at the early fabrication process, only a specific shape transformation behavior can be produced under external stimuli, and thus has limited the development of hydrogel actuators toward the biomimetic shape deformation behavior. Herein, a novel bilayer hydrogel having a thermoresponsive actuating layer and a metal ion‐responsive memorizing layer is proposed, therefore, a 2D hydrogel film can be fixed into various 3D shapes via supramolecular metal‐ligand coordination, with further realizing programmable 4D shape deformation under the stimulus of temperature. By manipulating the temporary shapes via shape memory behavior, various temporary anisotropic structures can be obtained via the bilayer hydrogel, thus producing diverse reversible shape deformation performances, which is expected to promote the development of intelligent polymeric materials.

Stretchable and Thermally Responsive Semi‐Interpenetrating Nanocomposite Hydrogel for Wearable Strain Sensors and Thermal Switch

“…As shown in Figure 4a, the LCST of the conductive hydrogel was about 34 °C (PNIPAM has an LCST at around 32 °C in aqueous solutions. [34][35][36] ). It is concluded that LCST can be precisely justed by the content of the copolymer and the molar ratio of monomers.…”

Recent progress in the shape deformation of polymeric hydrogels from memory to actuation

“…10a ). 88 Unlike in the case of traditional hydrogel actuators, in this system, temporary anisotropic structures could be formed and programmed using shape memory, and various morphing transformations could be induced by the actuating process. For instance, the wings of a butterfly-shaped bilayer hydrogel could first be fixed into a curved shape by metal ion–Alg interactions, and the wings could then deform from the curved shape into a soaring shape in response to a heat stimulus.…”

Recent Progress in Bionic Skin Based on Conductive Polymer Gels

“…Electrical current is conducted by the migration of ions that results from adding inorganic salt, or ionic liquid and the conductivity could be simply tuned by the quantity of ions. Ionic conductive gels are usually endowed with stretchability, [12,42,53] compliance, [54,55] adhesive, [39,55] self-healing ability, [39,54,55] shape memory, [56] and transparent properties [24,39] by changing the precursor content and designing the polymer structure. They are promising materials for bionic skin, [26,[57][58][59][60][61] which are flexible ionic conductive polymer sensors that mimic the sensing functions of mammalian skin.…”