Lightweight and Flexible Phase Change Materials for Thermal Management with Integrated Rapid Heating and Cooling Functions

Development of flexible electronics and functional textiles requires phase change material (PCM) with mechanical flexibility. Here, a lightweight and flexible composite PCM has been prepared by loading melted paraffin wax (PW) into a robust carbon nanotube (CNT) scaffold. This flexible PW/CNT PCM with 85 wt.% PW loading shows a mechanical strength of 3.1 MPa and a tensile strain up to 21%, suggesting a high flexibility and structural integrity that cannot be found in traditional carbon foams. The greatly increased toughness of the flexible PCM was ascribed to the interwoven structure of the CNT scaffolds bonded by PW. Additionally, the material maintains 99.78% of the initial capacity after 200 cycles. High thermal storage capacity (183.93 kJ kg −1 ) and cycling stability endow the nanocomposite with a stable cooling function, while the CNT scaffolds are conductive and allow the flexible nanocomposite to display rapid heating function. Additionally, the as-prepared flexible PW/CNT PCM has greatly enhanced thermal conductivity, which causes rapid thermal response for heat transfer. Thereby, the nanocomposite materials show potential for use over a wider temperature range and multi-functional thermal management. Graphical Abstract