A novel stearic acid/expanded graphite/Fe3O4 composite phase change material with effective photo/electro/magneto-triggered thermal conversion and storage for thermotherapy applications

Abstract

Composite phase change materials (CPCMs) have demonstrated high potential in thermotherapy; however, their poor energy conversion limits thermal−charge performance, thus negatively affecting their practical applications. Herein, we combined stearic acid (SA), expanded graphite (EG), and Fe3O4 nanoparticles (NPs) to obtain an 80 wt% SA/EG/Fe3O4 CPCM with multisource−triggered thermal conversion and storage abilities. The CPCM was equipped with a photothermal conversion facilitated by high light absorption of EG and localized surface plasmon resonance of Fe3O4. The high electrical conductivity of EG also offered the CPCM with an effective electrothermal conversion. An accelerated magnetothermal conversion was further achieved for the CPCM owing to the superparamagnetism of Fe3O4 NPs. Resultantly, the 80 wt% SA/EG/Fe3O4 CPCM could be facily charged as applied with either low−energy electricity (2.0 V), actual sunlight radiation (98−110 mW/cm2), or alternating magnetic field (120 W). In addition, it exhibited relatively high thermal storage capacity (152.4 J/g), excellent leakage resistance, and high thermal stability, conductivity, and cycling reliability. As in the form of a heat pack, the 80 wt% SA/EG/Fe3O4 CPCM maintained a heat release to a human back within 50–52 °C for 34 min, overtaking the criteria for high−temperature thermotherapy. The proposed multisource−triggered thermal conversion abilities and suitable thermal properties made SA/EG/Fe3O4 CPCM promising for multiple energy utilization and practical thermotherapy applications.

Keywords

• Stearic acid/expanded graphite/Fe3O4
• Photothermal conversion
• Electrothermal conversion
• Magnetothermal conversion
• Thermotherapy