Integration of phase change materials with multi-responsive halloysite nanotubes for efficient Pickering emulsification of high-viscosity oil

In view of the low fluidity caused by the high viscosity of viscous oil, a rational construction of emulsifiers with in situ heating function is highly desirable to power a high-viscosity oil emulsification process. Herein, we demonstrate a novel composite phase change material (PCM) with the dual functions of photothermal and magnetic-thermal conversion to realize the efficient Pickering emulsification of viscous oil. The superior photo/magnetic-thermal response characteristics together with its excellent energy storage and heat release properties endow the designed composite PCM with a good viscosity reduction capacity, thus greatly promoting the emulsification of viscous oil. Owing to the polydopamine (PDA) and Fe3O4 coating, the temperature of functionalized composite PCMs could rapidly reach 80.9 °C and 68.5 °C under simulated sunlight illumination and an alternating magnetic field, respectively. The viscosity of crude oil can be significantly reduced when it comes into contact with heated materials. Most importantly, due to the encapsulation of PEG, the slow release of the stored heat ensured a sustained reduction in the viscosity of the oil over a considerable period of time and greatly improved the energy utilization efficiency simultaneously. Overall, the rationally designed multifunctional composite PCM with both in situ heating characteristics and Pickering emulsification properties provides a new solution for the emulsification of high-viscosity oil.