Composite Shell Microcapsules With Room Temperature Phase‐Change Properties and High Thermal Storage Density

Abstract Inorganic hydrated salts, noted for their high thermal storage density, excellent thermal conductivity, and non‐toxicity, are suitable candidate material for thermal management, particularly in enhancing human living environments when their phase transition points are near room temperature. Herein, we present an efficient and environmentally friendly microencapsulation method for inorganic hydrated salt through organic phase separation method. Eutectic hydrated salt (EHS) consisted of sodium carbonate decahydrate (SCD) and disodium hydrogen phosphate dodecahydrate (DHPD) was prepared as the core material while the mixture of ethyl cellulose (EC) and acrylonitrile‐butadiene‐styrene (ABS) as composite shell materials. Various characterization techniques were used to evaluate the micromorphology, chemical structure, thermal properties and thermal stability of the microcapsules. The resulting microcapsules exhibited a phase change temperature of 22.6 °C with a remarkable enthalpy of 131.4 J/g. Particularly, the enthalpy remained at 117.7 J/g even after 50 thermal cycles, indicating stable cycling thermal reliability. Furthermore, it was confirmed that the EHS was effectively encapsulated within the composite shell, and the microcapsules had a quasi‐spherical shape and core‐shell structure. More importantly, this method of microencapsulation could potentially be extended to other liquid hydrated salts at room temperature, offering a versatile approach for future applications.