SWCNT-Encapsulated Phosphorus-Grafted Stearyl Alcohol as a Flame-Retardant Phase-Change Material with Superior Thermal Properties

Organic phase-change materials (OPCMs) are one of the most preferred media for thermal energy storage (TES) applications but are troubled by their low thermal conductivity, leakage, and flammability problems. Herein, stearyl alcohol (SAL), as an OPCM, was first chemically bonded with phosphorus oxychloride (POCl3) to reduce its flammability and then encapsulated in a single-wall carbon nanotube (SWCNT) skeleton to address the low thermal conductivity and leakage issue, obtaining a flame-retardant form-stable phase-change material film (PCMF). As a result, a promising heat storage capacity (191.3 kJ/kg) and superior thermal stability of the modified SAL were achieved as evaluated via differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA) testing. Then, microscale combustion calorimetry (MCC) testing was carried out, showing that the peak of the heat release rate (PHRR) and total heat release (THR) of the modified SAL were, respectively, reduced by 24.4% and 24.3% compared to bare SAL. After encapsulating the modified SAL into the SWCNT skeleton, the PHRR and THR values of the as-prepared PCMF can be further reduced because of the synergistic effect between the phosphorus group and the SWCNT skeleton, while the electrical and thermal conductivity of the PCMF were significantly improved, simultaneously. In addition, the obtained PCMF presented excellent light-to-thermal conversion and thermal energy storage performance. Thus, the strategy presented in this work provides a general method to extend the OPCMs application with superior flame-retardant properties.