A flexible composite phase change material with ultrahigh stretchability for thermal management in wearable electronics

Application of phase change materials (PCMs)-based thermal management technology in flexible electronic devices has been inhibited due to the leakage and strong rigidity of PCMs. A novel flexible composite PCMs with ultrahigh extensibility was developed in this paper. Concretely, a kind of paraffin@copper (PA@Cu) microcapsule with paraffin as core and nano-Cu particle as “flexible” metal shell was prepared by a simple Pickering emulsion method in an aqueous medium. The encapsulation ratio of paraffin reached 98wt%. Then the PA@Cu microcapsules were introduced into uncured liquid silicone to fabricate flexible composite PCMs (PA@Cu/SE). SEM results demonstrated that the microcapsules were tightly and uniformly wrapped in the three-dimensional network structure of silicone elastomer matrix. Owing to the good compatibility of PA@Cu with the polymer elastomer and a barrier for the melted PA provided by the “flexible” nano-Cu shell, the resulting composite PCMs present superior flexibility and thermal reliability. Tensile tests showed that the flexible composites with a relative higher loading of PA@Cu (40wt%) exhibit outstandingly larger extensibility (> 730%) than many reported literatures. In addition, the composites presenting superior thermal protection for biological tissue make them well-suited for thermal management in wearable electronics. Graphical abstract