Development of dual-shell phase change microcapsules with enhanced thermal conductivity and photothermal conversion efficiency for advanced building thermal management

To enhance the thermal conductivity (k) and photothermal conversion efficiency of phase change microcapsules, we developed dual-shell phase change microcapsules via a bonding method. The outer shell layer consists of molybdenum disulfide (MoS 2 ), and the inner shell layer is made of melamine-formaldehyde (MF) resin. The prepared phase change microcapsules exhibit excellent heat storage, thermal stability, thermal conductivity, photothermal conversion, and flame retardancy performance. The effects of the MoS₂ shell layer proportion on the microstructure, leakage performance, thermal conductivity, photothermal conversion efficiency, heat storage performance, and flame retardancy of the microcapsules were investigated. Additionally, the mechanisms behind the enhancement of photothermal conversion and thermal conductivity in the dual-shell microcapsules were analyzed. The results indicate that when the MoS₂ shell layer proportion reaches 10 %, the phase change enthalpy of the dual-shell microcapsules is 148.2 J/g, with an encapsulation efficiency of 67.9 %. Compared to single-shell microcapsules made solely of MF resin, the thermal conductivity of the dual-shell microcapsules improved by 172.2 %. When applied to building energy conservation, the microcapsules can more rapidly bring indoor temperatures to a comfortable level while delaying heat loss after sunset, thereby improving occupant comfort and reducing the use of high-energy-consuming equipment such as air conditioning. Furthermore, the MoS₂-MF dual shell significantly enhances the flame retardancy of the phase change materials, enhancing safety. The dual-shell phase change microcapsules developed in this study offer the advantages of a simple preparation method, demonstrating immense potential for applications in building energy conservation and solar thermal utilization.