Controlled Latent Heat Phase-Change Microcapsules for Temperature Regulation

Microencapsulationof phase-change materials (PCMs) is of greatvalue and significance for improving energy efficiency and reducingcarbon dioxide emissions. Here, highly controllable phase-change microcapsules(PCMCs) with hexadecane as the core material and polyurea as the shellmaterial were developed for precise temperature regulation. A universalliquid-driven active flow focusing technique platform was used toadjust the diameter of PCMCs, and the shell thickness can be controlledby adjusting the monomer ratio. In synchronized regime, the dropletsize is only related to the flow rate and excitation frequency, whichcan be accurately predicted by the scaling law. The fabricated PCMCshave uniform particle size with a coefficient of variation (CV) under2%, smooth surface, and compact structure. Meanwhile, under the goodprotection of a polyurea shell, PCMCs exhibit fair phase-change performance,strong heat storage capacity, and good thermal stability. The PCMCswith different sizes and wall thickness show obvious differencesin thermal properties. The feasibility of the fabricated hexadecanephase-change microcapsules in phase-change temperature regulationwas verified by thermal analysis. These features indicate that thedeveloped PCMCs by the active flow focusing technique platform havebroad application prospects in thermal energy storage and thermalmanagement.