A multifunctional flexible composite phase-change film with excellent solar driven thermal management

The development of multifunctional films with integrated temperature regulation, photothermal conversion, and bendability is urgently needed for personal thermal management products. In this paper, aminated multi-walled carbon nanotubes modified phase-change microcapsules (ACNTs-PCMC) were synthesized. Subsequently, a flexible polyvinyl alcohol (PVA)/graphene/ACNTs-PCMC composite film (PGAMF) with a three-dimensional sandwich structure was prepared by a simple tape-casting method. The obtained PGAMF films possessed a phase-change enthalpy of 45.5 ± 0.7 J/g. The designed sandwich structure can fix the ACNTs-PCMC microcapsules inside the PGAMF films through the bonding effect of the PVA to prevent them from falling off and sliding, so that the PGAMF composite films have the proper mechanical properties and excellent flexibility. More importantly, the PGAMF composite films had a high photothermal conversion efficiency of 88.8%. In the cold environment, the center temperature of the PGAMF composite film adhered to the fiber fabric driven by a low solar radiation was 14.5 ± 0.5 °C higher than that of the fiber fabric without the PGAMF composite film. Therefore, the multifunctional composite films with flexibility, heat storage and solar-to-heat conversion prepared in this study have broad application scenarios in heat preservation in low temperature areas and solar-driven thermal management engineering.