Ultrafast and continuous synthesis of phase change nanocapsules using salt-accelerated microwave-assisted polymerization

Abstract

Using nanoencapsulated phase change materials (NanoPCMs) for thermal energy storage has great application prospects in addressing the mismatch issues between energy supply and demand. However, the rapid, large-scale preparation of NanoPCMs is a challenge. Here, we developed a facile, efficient, green, and continuous method for the ultrafast preparation of NanoPCMs for energy storage using microwave-assisted polymerization with cross-linked poly(methyl methacrylate) and the PCM n-octadecane utilized as the shell and core materials, respectively. Sodium chloride (NaCl) acted as a microwave sensitizer and synergized with emulsifier to control the particle size of the NanoPCMs. Through orthogonal experiments, we investigated the effects of microwave power, temperature, and polymerization time on the properties of the NanoPCMs. The optimum conditions were 1.0 wt% NaCl, 60 °C, 10 min, and 600 W. The resulting NanoPCMs with uniform, spherical, core–shell structures were successfully utilized as thermal energy storage materials. The encapsulation efficiency was 50.8% and the NanoPCMs exhibited a particle size of ca. 95 nm, a high latent heat storage capacity of ca. 114.9 J g⁻¹, and good thermal stability. In particular, the reaction time was greatly reduced from 12 h to 10 min, 100 times faster than conventional hydrothermal polymerization. Based on these parameters, the continuous, efficient production of microwave-assisted NanoPCMs was realized through reactor design, laying a foundation for the commercial production of NanoPCMs.