Tough Interfacial Adhesion of Bilayer Hydrogels with Integrated Shape Memory and Elastic Properties for Controlled Shape Deformation

Abstract

The weak adhesion between two hydrogel layers may lead to the delamination of bilayer hydrogels or low force transfer efficiency during deformation. Here, tough interfacial adhesive bilayer hydrogels with rapid shape deformation and recovery were prepared by simple attachment-heating of two gel layers. The bilayer hydrogels, composed of a shape memory gel (S-gel) and an elastic gel (E-gel), exhibited extremely tough interfacial adhesion between two layers (Γ ∼ 2200 J/m2). The shape deformation and shape recovery of the bilayer hydrogels, tuned by “heating–stretching” mode and “stretching–heating–stretching” mode, were rapid (<5 s) and no delamination between two gel layers was detected during shape deformation. Based on the fast shape deformation and recovery, the bilayer hydrogels could mimic the flower and hand, and a gel gripper could be fabricated to catch the object in the hot water. This work provides a simple method to prepare tough adhesive bilayer hydrogels with controlled shape deformation.

Gradient adhesion modification of polyacrylamide/alginate–calcium tough hydrogels

“…10 Although scientists have developed a series of integrated adhesive–tough hydrogels, 11–16 it is still difficult to obtain the synergy of adhesion and cohesion. 17 Janus hydrogels with a bilayer structure 18–20 or gradient structure 21–23 have significant advantages in simultaneously obtaining strong adhesion and high toughness of hydrogels.…”

Multi-responsive and conductive bilayer hydrogel and its application in flexible devices

“…Furthermore, an eight-arm gripper made of a bilayer hydrogel could grasp and release an object. Wang et al 25 prepared a strong-interfacial bilayer hydrogel consisting of a shape-memory layer and an elastic layer. The bilayer hydrogel underwent different deformations via various heating-stretching modes.…”

Injectable Thermogel Generated by the “Block Blend” Strategy as a Biomaterial for Endoscopic Submucosal Dissection

“…Herein, we suppose that a thermogel of the copolymer composed of poly­(ethylene glycol) (PEG) and some biodegradable polyesters such as poly­( d , l -lactide- co -glycolide) (PLGA) might be a suitable candidate for a good SFC. In addition to the excellent properties of conventional hydrogels, − this material undergoes a sol–gel transition upon heating, and the gelation temperature can be between the room temperature and the body temperature. − The fluid property of this material at the sol state at room temperature guarantees the low injection pressure and thus the convenient injection, while the semisolid state with a high modulus owing to the sol–gel transition at body temperature affords a good elevated pad.…”