Polyurea-Polyurethane Encapsulated CH₃COONa·3H₂O Phase Change Microcapsules with Ultrahigh Enthalpy for Chip Thermal Management

Microencapsulation technology is an effective method to enhance the thermal energy storage performance and operational reliability of phase change materials. However, inorganic hydrated salt phase change microcapsules have long faced challenges such as low encapsulation efficiency and insufficient thermal cycling stability due to the high salt concentration and hydrophilic nature of hydrated salts. In this study, sodium acetate trihydrate was employed as the core phase change material. Utilizing a water-in-oil inverse emulsion templating method, hydrophilic monomer diethylenetriamine and flexible PEG were spontaneously triggered to polymerize with hydrophobic monomer isophorone diisocyanate at the oil–water interface, successfully preparing SAT phase change microcapsules with a polyurea-polyurethane shell. These phase change microcapsules demonstrated outstanding thermal energy storage performance, exhibiting a phase change enthalpy as high as 258.9 J/g and an encapsulation efficiency of 93.03%. After 200 thermal cycles, the enthalpy retention rate remained at 98.1%. In a simulated chip thermal management experiment, compared to the control group without phase change microcapsules, the temperature control system incorporating these microcapsules extended the time required for the chip to reach 70 °C by 461.8%, showcasing exceptional thermal buffering performance. This work provides a novel approach for the preparation of SAT phase change microcapsules, and the fabricated microcapsules demonstrate significant potential for applications in the field of chip thermal management.