Novel stearic acid/graphene core–shell composite microcapsule as a phase change material exhibiting high shape stability and performance

• Core–shell stearic acid (SA)/graphene microcapsule is prepared by a latex technology.
• Graphene encapsulates SA latex particle in aqueous medium by electrostatic attraction.
• Obtained composite exhibits excellent performance as a shape-stabilized PCM.

A stearic acid (SA)/graphene composite microcapsule, having a core–shell structure, is prepared for the first time using a latex technology for use as a novel composite phase change material (PCM) for thermal energy management. Melted SA is dispersed in water using an anionic surfactant as a stabilizer and cooled to prepare a water-based latex containing negatively charged SA particles. A simple mixing of this latex with an aqueous dispersion of graphene, prepared with aid of a cationic surfactant, results in the self-assembly of graphene on a SA particle surface by an electrostatic interaction, allowing for the encapsulation of SA with graphene to form a core–shell composite microcapsule. The protective graphene shell gives an excellent shape stability to the composite during phase change and a substantial improvement in thermal stability of the active SA core. In addition, the core–shell structure contains a high weight fraction of the active core material due to the ultra-thin graphene shell having high thermal conductivity. This results in a high performance PCM with a large latent heat and an improved thermal conductivity.

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