Thermal Management Applications of Phase Change Microcapsules with the PDA‐Modified TiO ₂ as a Multilayered Shell

Abstract The novel multilayer shell phase change microcapsule (NePCM), which consists of paraffin/titanium dioxide‐polydopamine (PW/TiO 2 ‐PDA), is prepared by a two‐step method. The PDA deposits on the TiO 2 surface through self‐polymerization of dopamine (DA). The NePCM5 and NePCM‐PDA‐0.6 samples have maximum phase change enthalpies of 106.43 and 80.12 J g −1 , respectively. There is no trend of continuous increase in phase change enthalpy with increasing PDA content, which may attribute to the agglomeration behaviors caused by the excessive PDA content. The PW encapsulated within the microcapsules maintains stable phase change performances during the storage and release processes of thermal energy. The as‐prepared microcapsules show regular monolayer and multilayer spherical core‐shell structures. The average size of the NePCM5 and NePCM‐PDA‐0.6 samples are approximately 259.4 and 311.4 nm, respectively. The particle size of nanoscale microcapsules is advantageous for improving heat transfer efficiency, maintaining uniform distribution, optimizing mechanical properties, and reducing phase change lag of thermal storage systems (TES) in industrial applications. The obtained microcapsules are applied to modify thermal insulation coatings based on the low thermal conductivity of the PW. The maximum temperature difference and the lowest thermal conductivity reach 19.70 °C (5 mm) and 0.126 W (m·K) −1 (5 mm) after adding the NePCM‐PDA‐0.6. The resulting coating have a high stability, low thermal conductivity, superior mechanical strength, high heat storage and heat preservation effect. Therefore, the stability of the PW can be further enhanced and the thermal conductivity of PW/TiO 2 microcapsules is reduced by coating the TiO 2 shell layer. The double‐shell microcapsules possess distinct advantages and wide application prospects in coatings, construction and textiles fields.