Multiresponsive Shape-Stabilized Hexadecyl Acrylate-Grafted Graphene as a Phase Change Material with Enhanced Thermal and Electrical Conductivities

A phase change material (PCM) essentially making up hexadecyl acrylate-grafted graphene (HDA-g-GN) was fabricated via a solvent-free Diels–Alder (DA) reaction. The novel material exhibits multiresponsive, enhanced thermal and electrical conductivities and valid thermal enthalpy. In addition, the optimum DA reaction conditions were explored. A variety of characterization techniques were used to study the thermal, crystalline, and structural properties of HDA-g-GN. The melting and crystallizing enthalpies of HDA-g-GN were as high as 57 and 55 J/g, respectively. Furthermore, the melting and freezing points of HDA-g-GN were 29.5 and 32.7 °C, respectively. The thermal conductivity of HDA-g-GN reached 3.957 W/(m K), which is well above that of HDA itself and the previously reported PCMs. HDA-g-GN exhibited an excellent electric conductivity of 219 S/m. Compared to HDA, the crystalline activation energy of HDA-g-GN decreased from 397 to 278 kJ/mol (Kissinger model) and 373 to 259 kJ/mol (Ozawa model). Moreover, HDA-g-GN exhibited excellent thermal stability, shape stability, and thermal reliability. More importantly, HDA-g-GN can be employed to realize high-performance light-to-thermal and electron-to-thermal energy conversion and storage, which provides wide application prospects in energy-saving buildings, battery thermal management system, bioimaging, biomedical devices, as well as real-time and time-resolved applications.