Synthesis and Characterization of Erythritol-Based Nanoencapsulated Phase-Change Materials for High-Temperature Latent Functional Thermal Fluid

Erythritol-based nanocapsules with a phase-change temperature of 120 °C are successfully prepared under very mild conditions. The nanocapsules are produced via multiple crystallization precipitations from a saturated erythritol aqueous solution, followed by SiO 2 coating using a sol–gel method. Their nanostructure and elemental composition are characterized using scanning electron microscopy and energy-dispersive X-ray spectroscopy. The latent heat of the nanocapsules is measured with a differential scanning calorimeter. The erythritol nanocapsules, with an average size of ≈220 nm, exhibit a melting enthalpy of 192.7 J g −1 . Notably, the supercooling degree of the nanocapsules is reduced by ≈30.0 °C compared to pure erythritol. After 200 thermal cycles, the heat storage performance of the nanocapsules shows only a 7.6% decrease. A latent heat functional thermal fluid, suitable for high-temperature heat transfer, is prepared by dispersing the nanocapsules in silicone oil. The thermal conductivity and specific heat capacity of this fluid increase by 20.5% and 283.3%, respectively, compared to pure silicone oil. These findings demonstrate that erythritol nanocapsules significantly enhance the thermal properties of high-temperature heat transfer fluids, highlighting their potential for high-temperature heat storage and transfer application.