Highly ordered rubbers with a giant elastocaloric effect.

Abstract

Rubbers have emerged as the leading candidates for solid-state refrigerants in elastocaloric cooling, owing to their low driving force and high coefficient of performance. However, their elastocaloric effect is generally limited by the intrinsic disorder nature of their molecular chains. Here, we report that the rubbers synthesized from a cycloaliphatic diisocyanate and an ordered polyol exhibit both high short- and long-range ordering, giving rise to strain-induced crystallinity of ordered chains up to 66.3%. Consequently, the structurally optimized rubber demonstrates an adiabatic temperature change of 20.1 kelvin and an isothermal entropy change of 179.8 joules per kilogram per kelvin, greatly surpassing previously reported elastocaloric polymers. Moreover, we develop a rubber-based roll-to-roll stretching refrigeration device that addresses the key limitations of conventional stress-based elastocaloric polymer devices.