Synergistic enhancement of thermal properties in n-octadecane microcapsules via graphene oxide and alkylated derivatives

The growing demand for efficient thermal management has increased the importance of phase change materials (PCMs). Microencapsulation technology mitigates the leakage issue of liquid-state PCMs. However, enhancing the thermal conductivity and structural stability of microencapsulated PCMs (MEPCMs) remains a challenge. Graphene oxide (GO) and its chemically functionalized derivatives have shown great potential in enhancing the performance of MEPCMs. In this study, GO and octadecylamine-grafted GO (GO-ODA) were employed as thermally conductive fillers to modify n -octadecane@melamine-formaldehyde resin microcapsules. Four formulations were developed by varying the spatial distribution of GO and GO-ODA within the microcapsules. The dispersion of GO-ODA in the core was found to reduce defects in the shell structure, while distributing the additives across the core, interface, and shell promoted the formation of a continuous thermal conduction network. The experimental results indicate that, with a filler content of 0.2 wt%, the thermal conductivity increased by 5.8 times, reaching 0.587 W/(m·K), compared to the unmodified MEPCM with a value of 0.086 W/(m·K). Additionally, the leakage rate was reduced by 87.5%, significantly enhancing the structural stability of the microcapsules.