A Fast, Reversible, and Robust Gradient Nanocomposite Hydrogel Actuator with Water‐Promoted Thermal Response

Abstract

Poly(N-isopropylacrylamide)/Laponite (PNIPAM/Laponite) gradient nanocomposite hydrogel actuators are developed as temperature-controlled actuators with excellent performance using a facile electrophoresis method. The actuators exhibit a rapid (20 s response time) and reversible response, as well as large deformation (bending angle of 231°), which is due to the graded forces generated by the thermo-induced anisotropic shrinkage and extension of the gradient hydrogels. A good linear relationship is observed between the maximum bending angles and the corresponding temperatures for the actuators with fixed sizes. Moreover, the gradient hydrogel with high water content achieved larger actuation angles and shorter response time than the one with low water content, showing an interesting water-promoted effect. Meanwhile, different types of actuators are designed to suit for more specific scenarios, and may be used for various applications, such as biosensing, artificial organization, and transportation of targeted objects.

Nanoparticle–Polymer Synergies in Nanocomposite Hydrogels: From Design to Application

“…In addition, electrical stimuli could induce the formation of gradient and orderly structures in NC gels. For example, a gradient structure of PNIPAAm/clay NC gels could be prepared by applying an external DC electric field during polymerization . The negative charge on the surface of the laponite tends to move toward the anode in the electric field, which induces gradient structure and anisotropic properties along the direction of the electric field ( Figure ) .…”

“…For example, a gradient structure of PNIPAAm/clay NC gels could be prepared by applying an external DC electric field during polymerization . The negative charge on the surface of the laponite tends to move toward the anode in the electric field, which induces gradient structure and anisotropic properties along the direction of the electric field ( Figure ) . Based on the gradient structure and stimuli‐responsive properties of hydrogels, a novel actuator was fabricated, which gave the gradient NC gels good prospects in the fields of tissue engineering, artificial organ, and sensor technology.…”

“…Schematic illustration of the preparation of the gradient PNIPAAm/clay nanocomposite hydrogel in a DC field. Reproduced with permission . Copyright 2018, Wiley‐VCH.…”

“…Artificial soft robots are flexible devices that can perform complex and programed motions driven by external commands. NC gels with controllable mechanical properties can convert diverse environmental stimuli, including temperature, light, humidity, phase and volume change, without structural failure, making them an ideal candidate for artificial soft robots that can perform macroscopic actuation by structure and shape transitions under external stimuli …”

Non‐Volatile Glycerin Gel Enhanced by Sub‐5 nm Particles with Super Elasticity, Recoverability, and High Temperature Resistance

“…To achieve a gel material with strong mechanical properties, there are generally several methods based on previous research, such as double‐network gels, sliding‐ring gels, topological gels, and nanocomposite gels . Among them, nanocomposite gels can offer facile synthesis, superior mechanical strength, sensitive stimuli, and outstanding reversible properties at the same time.…”