A Universal Zwitterionic Cross-Linking Strategy for Designing Conductive Soft Electronics with Enhanced Mechanical Properties.

ABSTRACT

Ionogels are emerging as promising electronics due to their exceptional ionic conductivity, stretchability, and high thermal stability. However, developing ionogels with enhanced mechanical properties without compromising conductivity and ion transport rates remains a significant challenge. Here, we report a zwitterionic cross-linker, 4-(2-(((2-(methacryloyloxy)ethyl)carbamoyl)oxy)ethyl)-4,14-dimethyl-8,13-dioxo-7,12-dioxa-4,9-diazapentadec-14-en-4-ium-1-propanesulfonate (MEPS) and utilized it to cross-link a variety of functional monomers, leading to the synthesis of conductive ionogels that exhibit both high mechanical strength and versatile applicability. Due to its abundant hydrogen bond donors/acceptors and zwitterionic moiety, MEPS exhibits several hundred times higher solubility in ionic liquids compared to conventional cross-linkers. As a proof-of-concept, the poly(acrylic acid-MEPS) ionogels demonstrate enhanced elongation, fracture toughness, and superior thermal stability, all while maintaining high conductivity due to the high affinity between ionic liquids and zwitterionic networks. Furthermore, MEPS-cross-linked poly(α-thioctic acid) electronics can be engineered as strain sensors, showing exceptional antifatigue properties and recyclability, remaining stable and functional over 300 consecutive cycles. This universal cross-linking strategy not only improves the overall performance of ionogels but also contributes to the development of next-generation soft electronics with enhanced functionality and durability.