Development of supramolecular ionic gels with self-healing capability and biodegradability using a bioderived ionic liquid and poly(vinyl alcohol)

Abstract

Gels are promising candidates for environmental sensing and implants because of their high stretchability, ionic conductivity, and low toxicity toward the environment and human body. Self-healing gels can recover their mechanical and electrical properties after rupturing under environments with harsh mechanical stress. However, current self-healing gels rely on healing agents, metal ions, or dynamic bonding; these materials exhibit toxicity and nonbiodegradability, hindering their use in environmental sensing and implant applications. Herein, we developed supramolecular ionic gels (SIGs) with self-healing capability and biodegradability through the physical crosslinking of poly(vinyl alcohol) (PVA) and the bioderived ionic liquid (IL) choline lactate. Fourier-transform infrared spectroscopy and wide-angle X-ray scattering revealed that the IL and PVA formed hydrogen bonds, thereby resulting in nanocrystalline structures in the SIGs. After cutting, dynamic bonding helps self-healed SIGs recover fracture stress and strain by 39% and 45%, respectively, compared to pristine SIGs. Furthermore, hydrogen bonding is a reversible reaction that enables ruptured SIGs to reconfigure their shapes after tensile-stress tests. The reconfigured SIGs involve fracture stress and strain comparable with those of the initial SIGs. This study provides insights into bio/ecoresorbable electronics with high mechanical robustness, which can help develop transient devices for wearables, implants, and environmental sensing.