Recent Progresses in Liquid-Free Soft Ionic Conductive Elastomers†

Comprehensive SummaryWith the rapid growth of soft electronic and ionotronic devices such as artificial tissues, soft luminescent devices, soft robotics, and human-machine interfaces, there is a demanding need to accelerate the development of soft ionic conductive materials. To date, the first-generation ionotronic devices are mainly based on hydrogels or ionogels. However, due to their intrinsic drawbacks, such as freezing or volatilization at extreme temperatures, and the leakage problem under external mechanical forces, the reliability of ionotronic devices under harsh conditions remains a great challenge. The advent of liquid-free ionic conductive elastomers (ICEs) has the potentials to solve the issues related to the gel-type soft conductive materials. The free ions shuttling within the ion-dissolvable polymer network enable liquid-free ICEs to exhibit unparalleled ionic conductivity and elasticity. Moreover, by tuning the composition and structure of the polymeric network, it is also feasible to integrate other desirable properties, such as self-healing ability, transparency, biocompatibility, and stimulus responsiveness, into liquid-free ICE materials. In this review, we summarize the design strategies of recently reported liquid-free ICEs, and further explore the methods to introduce multifunctionality, which originate from the rational molecular design and/or the synergy with other materials. Moreover, we highlight the representative applications of liquid-free ICEs in soft ionotronics. It is believed that liquid-free ICEs might provide a unique material platform for the next-generation ionotronics.