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.