Ultralight and flexible carbon-based phase change composites with high porosity for enhanced shape memory and photothermal conversion performance

Phase change materials (PCM) have limited practical application due to their high rigidity, poor photothermal conversion, low thermal conductivity, and insufficient drive capability. In this work, a flexible CF/(HO-BNNS@CuO)/PEG composite with high thermal conductivity and photothermal conversion capacity was prepared by using carbon foam (CF) as flexible supporting material, hydroxyl boron nitride nanosheets (HO-BNNS) as thermal conductivity filler, and copper oxide (CuO) as photothermal conversion agent. In CF/(HO-BNNS@CuO)/PEG containing 90 wt% PEG, the photothermal conversion storage efficiency reached 91.8% and the thermal conductivity was improved by 348% compared to pure PEG. It also presents excellent thermally driven shape memory properties (98 s) with the elastic characteristics of CF and the phase change characteristics of PEG. This provides a strategy to prepare flexible PCM with outstanding comprehensive performance, which helps to broaden the practical application of PCM. • Carbon foam (CF) has high elastic modulus and complete three-dimensional skeleton. • The photothermal conversion storage efficiency of CF/(HO-BNNS@CuO)/PEG(90) is as high as 91.8%. • CF/(HO-BNNS@CuO)/PEG(90) presents excellent thermally driven shape memory properties (98 s). • CF/(HO-BNNS@CuO)/PEG(90) has high heat storage capacity and fast heat transfer speed (1.12 W/m·K).