Transparent, Mechanically\nRobust, Adhesive, Temperature-Tolerant,\nand 3D Printable Nanocomposite Ionogels for Flexible Sensors

Abstract

Ionogels are emerging as soft materials for flexible\nstrain sensors.\nHowever, the integration of multiple functionalities into a single\nionogel for diverse applications in complex scenarios remains a challenge.\nIn this study, we present a multifunctional nanocomposite ionogel\nthat combines high strength, transparency, stretchability, temperature\ntolerance, adhesiveness, and 3D printing capabilities. The ionogels\nare fabricated through a one-step photopolymerization process involving\nacrylic acid and 2-acrylamide-2-methylpropanesulfonic acid in an ionic\nliquid, with Al­(OH)₃ nanoparticles serving as cross-linkers.\nThe resulting ionogels exhibit robust noncovalent interactions, including\nionic coordination, hydrogen bonding, and ionic dipole interactions,\nproviding exceptional mechanical strength, conductivity, and wide\ntemperature tolerance while ensuring strong adhesion to various substrates.\nWearable strain sensors based on these ionogels can accurately detect\nand differentiate a range of movements, from large body motions such\nas bending limbs to subtle distinctions such as writing different\nletters. Additionally, the pregel solution can serve as printing ink\nfor the rapid and efficient mass production of 3D printed high-precision\nmicrocircuits. Impressively, the nanocomposite ionogels exhibit a\nhigh latent heat value of 240 J g^–1 at a melting\ntemperature of −65 °C, suggesting significant potential\nfor cold energy storage in ultralow-temperature cold-chain transportation\nsystems. Thus, these outstanding features of the ionogels offer a\npromising strategy for advancing wearable electronics and cold energy\nstorage systems.