Synthesis and properties of methyl palmitate-polyurea phase change microcapsules

In this study, a methyl palmitate-polyurea phase change microcapsule (MPCM) was successfully synthesized by interfacial polymerization with methyl palmitate with high latent heat as the core material and tolylene-2,4-diisocyanate (TDI) and diethylene triamine (DETA) as the shell monomers. The effects of emulsifier type and content, cosolvent, reaction rate and core-shell mass ratio on the phase change properties of microcapsules were systematically discussed, and the optimum process was determined. A series of characterization techniques were used to analyze the composition, crystal structure, morphology, microstructure, particle size distribution and thermal performances of the microcapsules. The experimental results presented that the microcapsules synthesized under the optimal conditions had outstanding encapsulation efficiency (72.42 %) and encapsulation rate (70.77 %) with melting temperature and solidification temperature of 27.2 °C and 13.8 °C, and melting enthalpy and solidification enthalpy of 160.5J/g and 157.3J/g, respectively. Moreover, the resulting microcapsules had regularly spherical morphology with compact and smooth surface, and uniform particle size distribution with average particle size of 909.94 nm. Meanwhile, the microcapsules possessed excellent thermal stability, low thermal conductivity (0.2932 W K −1  m −1 ) and excellent thermal reliability. These characteristics made methyl palmitate-polyurea MPCMs have a broad application prospect in the field of thermal insulation.