Electrostatic Self-Assembled Carbon Black Phase-Change Microcapsules for Building Photothermal Conversion and Thermal Energy Storage

To enhance the photothermal response capability of phase change materials (PCMs), this study adopted a simple and efficient electrostatic self-assembly polymerization method. Using paraffin wax (PW) as the core material and silica/carbon black (CB) as the shell material, microcapsules were prepared as photothermal conversion and heat storage materials. The prepared carbon black phase change microcapsules (CB-MPCMs) exhibited excellent thermal storage performance, with a phase change enthalpy value of approximately 130.0 J g^-1, and the encapsulation efficiency could exceed 60%. These microcapsules can remain leak-free for long periods of time at temperatures as high as 80.0 °C. After multiple heating and cooling cycles, the phase change enthalpy of CB-MPCM remained stable. To address the challenges faced by phase-change microcapsule powders in practical applications, this study used a flexible nonwoven fabric as the substrate and attached the CB-MPCM to the flexible substrate using epoxy resin (ER) and a curing agent (CA). A transparent polycarbonate (PC) plate was used as the outermost layer to prevent contaminants and reduce heat loss. This method enabled the simple and rapid formation of CB-MPCM composite plates, which improved their application scope and methods for building thermal management. Under cyclic irradiation of 1 kW m^-2, these composite plates exhibited significant energy storage and release characteristics while maintaining stable performance. The research results indicated that it has broad application prospects in energy conservation and solar energy collection.