High Cycle‐Life Twistocaloric Cooling of Poly‐p‐Phenylene Benzodioxole Fibers

Abstract

It is an urgent need to develop efficient solid state cooling technologies and materials with high cycle life. Poly‐p‐phenylene benzodioxole (PBO) is a high performance fiber with excellent mechanical properties. In this work, for the first time, we report elasto‐ and twistocaloric cooling of PBO fibers by stretching and twisting of the PBO fiber bundles. The cooling temperature reached ‐0.4 K and ‐1.3 K, for fiber stretching and twisting, respectively. A self‐coiled PBO fiber achieved maximum cooling of ‐3.7 K upon stretching by 35% strain, with an exceptionally high cycle life of 200,000 times. During the twisting of the PBO fibers, we observed reversible changes in the intensity of the diffraction peaks in X‐ray diffraction patterns. A strain‐sensitive color change application was realized by coating a self‐coiled PBO fiber with liquid crystallite dyes. This work provides new perspectives for PBO fibers as a high cycle‐life solid‐state refrigeration material.This article is protected by copyright. All rights reserved