Long-Lasting Sustainable Self-Healing Ion Gel with Triple-Network by Trigger-Free Dynamic Hydrogen Bonds and Ion Bonds

Abstract

Considering their unsustainability, brittle shape, and weak mechanical properties, the application of conventional hydrogels suffers significant limits in various fields. Herein, with the contribution of sustainable cellulose nanocrystals (CNCs), a novel triple-network ion gel with high mechanical strength and self-healing ability is synthesized through a new method using ionic liquids instead of water. The obtained BmimHSO4-c ion gel exhibits more excellent mechanical properties by adding graphene oxide (GO) and sustainable CNCs, such as high tensile strengths (up to 15.9 MPa), excellent elongation (610%), and satisfied toughness (53.8 KJ/m3). In addition, with the interactions of ionic bonds between Bmim+ of ionic liquid and −OH of poly(vinyl alcohol) (PVA) as well as the hydrogen bonding among the gel, BmimHSO4-c results in 93.8% cure in strength and 93.3% cure in elongation after healing for 24 h in air without any external stimulus. Moreover, the newly prepared self-healing ion gel shows significant long-lasting self-healing performance. In the proposed system, ionic liquid not only acts as solvents, but also functions as a cross-linker, and a mechanism for the reaction of ionic liquids with poly(vinyl alcohol) PVA and participation in self-healing is first proposed.