Synthesized acrylate monomers to improve photothermal conversion efficiency and fire safety of PEG/black phosphorus (BP) phase change composites

The combination of photothermal components and phase change materials (PCMs) has received extensive attention. However, the incorporation of photothermal functionality into PCMs confronts the fatal problems of low utilization efficiency and performance compromise during processing. In this work, an acrylate monomer-passivation strategy was proposed to wrap photosensitive black phosphorus nanosheets (CG-BPs) to retain their intrinsic properties for high photothermal conversion efficiency. In addition, a flame-retardant acrylate (MCBDB) was further synthesized to crosslink with CG-BPs and build a framework for PEG1000 encapsulation. The resulting composite (cPCMs-1.2) was able to achieve a photothermal conversion efficiency of 85.3% even with a low content of CG-BPs (1.2 wt%) and unconcentrated irradiation. And benefiting from the synergistic flame-retardancy of CG-BPs and poly(MCBDB), the PCM composites displayed a reduced peak heat release rate of 38.7% compared with that of pristine PEG1000, indicating improved fire resistance. Considering its appropriate phase-change temperature, the application demonstration of the fabricated cPCMs-1.2 for human body hot compress was conducted, in which the promoting effect on blood circulation was observed. This work provides us with a new idea for the simple fabrication and new application of photothermal PCM with high photothermal conversion efficiency and application safety.