Hydrogel Rivet with Unidirectional Shape Morphing for Flexible Mechanical Assembly

Abstract

Integrating diverse materials and functions into highly additive produce has piqued global interest due to the increasing demands of intelligent soft robotics. Nevertheless, existing assembly techniques, especially supramolecular assembly, heavily rely on precise chemical design and specific recognition. These approaches may prove inadequate when confronted with diverse external demands. Inspired by the traditional mechanical assembly, rivet connection, herein, we fabricated a thermo‐responsive hydrogel with unidirectional shape‐morphing and constructed a stable mechanical assembly by emulating the rivet connection mechanism. In this system, poly(acrylamide‐co‐acrylic acid) [P(AAm‐co‐AAc)] was employed to induce continuous swelling, while hexylamine‐modified polyvinyl alcohol (PVA‐C6) served as a molecular switch to control the swelling process. The hydrogel rivet was initially threaded through pre‐fabricated hollows in two components. Subsequently, upon the disassociation of alkane chains, the molecular switch would activate, inducing swelling and deformation at the ends of the hydrogel rivet and creating stable mechanical assembly via anchor structure. Moreover, to enhance the assembly strength, we introduced knots to guide the release of localized stress, thus encoding programmed deformations of the hydrogel. Additionally, by incorporating photo‐thermal nanoparticles, this system could be further remotely controlled by near‐infrared (NIR) light. This work presents a universal and efficient strategy for constructing stable mechanical assemblies without compromising overall softness, offering significant potential for the fabrication of integrated soft robots.This article is protected by copyright. All rights reserved