Microencapsulated phase change materials based on graphene Pickering emulsion for light-to-thermal energy conversion and management

The superior thermal behavior and light-to-thermal energy conversion performance are crucial for microencapsulated phase change materials (microPCMs) in thermal energy management. In this work, a series of paraffin@graphene/melamine-formaldehyde microPCMs based on graphene Pickering stabilizer were prepared by in-situ polymerization. Graphene was served as a Pickering stabilizer. We have undertaken a comprehensive study of the effects of different graphene concentrations and core/shell ratio on the microPCMs. The leakage rate test showed that the leakage rate of the microPCMs with 0.2 wt% of graphene is decreased by 93.20% than that of the microPCMs without graphene. Graphene promotes light-to-thermal conversion efficiency of microPCMs, which reaches to 90.7%. Additionally, the optical microscope (OM) and scanning electron microscope (SEM) were used to characterize the morphology of the Pickering emulsion droplet and microPCMs, respectively. Thermal properties of microPCMs were evaluated by differential scanning calorimetry (DSC) and thermal conductivity test. The results indicated that the latent heat of the microPCMs with core/shell ratio of 4/1 is 204.0 J g^‑1 and thermal conductivity of that is 0.707 W m^‑1 K^‑1. Furthermore, because of the leakage prevention performance, thermal conductivity and light-to-thermal conversion performance of microPCMs, it may be forecast that microPCMs possess significant applications in thermal energy storage management.