A transparent and robust ionogel prepared via phase separation for sensitive strain sensing

Abstract

Improving the mechanical properties of ionogels is crucial for their widespread practical application. Herein, physically crosslinked ionogels were proposed by copolymerizing two monomers, acrylamide (AM) and N,N-dimethylacrylamide (DMAAm), in an ionic liquid via random copolymerization. By leveraging the distinct hydrogen bonding capabilities of the two monomers, we controlled the hydrogen bond content in the ionogel and investigated its impact on the ionogel's structure, transparency, and mechanical properties. The resulting ionogel demonstrated outstanding mechanical properties, including a tensile strength of 8.94 MPa, an elongation at break of 404.4%, and a toughness of 21.94 MJ m⁻³. The ionogel not only exhibits exceptional transparency and thermal stability, but also possesses remarkable self-healing and shape memory capabilities. Moreover, it can be easily recycled using environmentally friendly methods. As expected, the ionogel exhibits excellent ionic conductivity and biocompatibility, making it suitable for various fields, including sensors, biomedical engineering, and smart materials. Therefore, the gel opens an effective avenue to fabricate flexible strain sensors, enabling the precise and accurate monitoring of human motion activities.