Design and Synthesis of Microencapsulated Phase-Change Materials with a Poly(divinylbenzene)/Dioxide Titanium Hybrid Shell for Energy Storage and Formaldehyde Photodegradation

A novel series of microcapsules with high thermal energy storage (TES) and formaldehyde photodegradation functions was successfully fabricated by eco-friendly Pickering emulsion polymerization without addition of co-emulsifiers. The microcapsules consist of paraffin as the phase-change core material and poly(divinylbenzene) (PDVB)/titanium dioxide nanoparticles (TiO2 NPs) as the hybrid shell. The silane coupling agent KH-570 was used to adjust the hydrophobicity of TiO2 NPs for improving the stability on the oil/water surface. Meanwhile, the effects of the modification degree and addition amount of TiO2 NPs on the morphology of the microcapsules were investigated in detail, where the size of the microcapsule was adjusted from the micron to the submicron scale. The as-fabricated integrated TES system was first verified for the higher potential of formaldehyde photodegradation than that of pure TiO2 NPs under UV lamp irradiation because the microcapsule provides TiO2 NPs with heat to accelerate the catalytic process. Furthermore, the defect that TiO2 NPs are easy to fall off from the microcapsule shell was overcome by anchoring the TiO2 NPs to the PDVB shell with covalent bonds for improving the durability and reliability. The dual-functional microcapsules as the indoor green building materials have a potential application on ambient temperature regulation and indoor air purification.