Dual-Layer Microencapsulated Phase Change Material Composite with Enthalpy-Active Shell for Thermal Absorption and Directional Heat Management

Abstract Localized heat accumulation in electronic devices degrades performance, safety, and cycle life. Phase change materials (PCMs) have been widely investigated for passive thermal regulation; however, conventional core–shell encapsulated PCMs often exhibit limited effective heat absorption because shell materials remain thermally inactive and heat transport in composite systems remains uncontrolled. In this study, the naturally derived materials gum arabic and gelatin were used as shell materials. The gum arabic/gelatin shell exhibited endothermic reactions over a wider range, providing additional heat absorption beyond the intrinsic phase change enthalpy of the PCM core. Two functionally differentiated composite systems were developed. To mitigate localized heat accumulation, two differentiated composites were developed to address localized heat generation in electronic devices. An insulation-oriented heptadecane and silica aerogel (SA) based composite (BPA/Heptadecane/SA) exhibits a through-plane thermal conductivity of 0.15 W/mK and a heat absorption capacity of 54.7 J/g, whereas eicosane and a heat-spreading-expanded graphite (EG) based composite (BPA/Eicosane/EG) exhibits an in-plane thermal conductivity of 4.80 W/mK and a heat absorption capacity of 59.3 J/g. The results confirm that the proposed enthalpy-enhanced shell structure functions as an active thermal damper and that the hierarchical composite architecture enables simultaneous thermal insulation and directional heat management to mitigate localized heating.