Enhanced Stimuli-Responsive Phase Change Gels through Pickling-Enabled Ion Permeation

Abstract

Supercooled phase change materials (PCMs) are desirable for thermal regulation in energy storage, electronics thermal management, and biomedical applications owing to their reversible phase change transitions and exceptional thermal energy storage capacity. Among these materials, hydrated salt phase change gels stand out due to their tunable mechanical properties and controllable solidification dynamics but are constricted by the trade-off between the low enthalpy and limited mechanical strength - a consequence of salt-ion-induced disruption of network crosslinking. Inspired by the ancient art of vegetable pickling, we develop stimuli-responsive phase change gels (PCGs) that simultaneously achieve ultrahigh stiffness and enthalpy through a novel ion permeation strategy. By leveraging the competitive hydration effect between salt ions and the polymer network—akin to the cucumber pickling mechanism—we engineer PCGs with unprecedented mechanical strength (up to 2120 MPa, the highest reported value for such materials) while maintaining exceptional thermal energy storage capacity (210 kJ/kg). The supercooling behavior of hydrated salts enables a haptic/temperature-triggered reversible transition between soft and rigid states. These PCGs exhibit outstanding low-temperature deicing performance, generating rapid thermal release even at −10 °C through stimuli-activated heating. Furthermore, our approach is robust, cost-effective, and easily scalable, opening new possibilities for further thermal management.