Preparation and performance of Heterogeneous photothermal conversion enhanced composite phase change materials

To address the heat transfer bottleneck in photothermal devices due to low material thermal conductivity and insufficient photothermal synergy, this study prepared a graphene-reinforced flexible stratified composite phase change materials (FSPCM) based on paraffin wax (PW), styrene-ethylene-butene block copolymer (SEBS), and graphene (Gr) system by utilizing Gr’s high thermal conductivity and broad-spectrum light-absorption properties. The design forms a “heat-absorbing-heat-conducting” functional gradient structure by alternately stacking a black high light-absorbing/heat-conducting Gr/PW/SEBS layer with a white phase-change light-transmitting PW/SEBS layer. The experimental results show that the phase transition enthalpy is 187.96 J/g in DSC test, and the mass loss is only 0.028 % after 200 thermal cycles, with excellent cycling stability. The layered gradient design significantly improves the interfacial heat transfer efficiency, and the thermal conductivity of the composite material reaches 1.53 W/(m·K). Through the positive feedback mechanism formed by the plasma resonance effect of Gr and the phase change transmittance of PW, the efficiency of the light-heat conversion is improved by 22.9 %. Through the xenon lamp light source simulation test, FSPCM in 500 W/m² irradiation heating rate of 0.87 °C/min, phase transition time shortened by 10 %, compared with the traditional homogeneous material Gr dosage reduced by 60 %, cost reduction of 22 %.