Self-assembly fabrication of GO/TiO2@paraffin microcapsules for enhancement of thermal energy storage

To increase the thermal energy utilization rate of phase change materials (PCMs), an efficient composite structure was devised by integrating graphene oxide (GO) nanosheets and the microencapsulated paraffin with TiO2 shell. A collection of GO/TiO2@paraffin microcapsules was prepared by interfacial condensation polymerization in a sol-gel system, and the microstructure, chemical composition, and thermal properties were studied. Herein, the composite appeared a spherical core-shell structural morphology, and the GO nanosheets self-assemble on the surface of the microcapsules by sharing electrons and hydrogen bonds. The latent heat of microcapsules is more than 160.75 J/g, and the thermal conductivity enhanced from 0.195 to 0.297 W·m−1·K−1 thanks to the highly thermally conductive of GO nanosheets. In addition, the thermal conductivity is almost doubled compared to paraffin and preserving a high phase change enthalpy. It can be observed that most GO nanosheets were dispersed evenly on the surface of TiO2@paraffin microcapsules without obvious agglomeration, while a series of results indicated that paraffin, TiO2, and GO were physically combined. The prepared GO/TiO2@paraffin microcapsules composite PCMs with high thermal conductivity and great energy storage density is widely promising for low temperature heat storage. At the same time, this work provides a novel idea for the application of carbon material in the field of thermal energy storage microcapsule composite PCMs modification.