Calcium Coordinated Poly(acrylic acid) Ion Gels for Strain Sensing

Abstract

Although ion gels show great promise for various applications, their large-scale practical implementation remains hindered by challenges such as poor mechanical properties, lack of self-healing and recyclability, and insufficient interfacial adhesion. Herein, supramolecular ion gels were fabricated via a one-pot UV-initiated polymerization of acrylic acid in the ionic liquid 1-ethyl-3-methylimidazolium ethylsulfate (EMImES) using calcium acetate as a dynamic coordination cross-linker. Calcium acetate introduces Ca2+ to form a physically cross-linked network through metal coordination with poly(acrylic acid) chains. The resulting ion gels are characterized by superior stretchability (964%), efficient self-healing (93%), recyclability (83%), high transparency (90%), and robust interfacial adhesion. Ion gel-based strain sensors can detect a range of deformations and human activities, providing sensitive (0–100%, gauge factor (GF) = 1.31), reproducible sensing signals (500 cycles). This work offers a strategy for synthesizing high-performance, recyclable ion gels for sustainable flexible electronics.