Fabrication and performances of microencapsulated phase change materials based on n-octadecane core and resorcinol-modified melamine–formaldehyde shell

A series of microencapsulated phase change materials (micro-PCMs) based on n-octadecane core and resorcinol-modified melamine–formaldehyde shell were synthesized by in situ polymerization method using different emulsifiers. The Fourier transform infrared spectra confirmed that the resorcinol-modified melamine–formaldehyde shell was successfully fabricated on the surface of the core material; however, the morphology investigation suggested that the sodium salt of styrene-maleic anhydride copolymer as an anionic emulsifier is optimal for the fabrication of the microcapsules in this study. And the microcapsules fabricated with a core/shell weight ratio of 75/25 have a compact surface of the shell and a mean particle size of below 20 μm with the centralized size distribution. The sample under this condition has much better phase change properties and a higher efficiency of encapsulation (about 92%) than the others through the evaluation of the differential scanning calorimetry, while it also exhibits an excellent stability from the anti-osmosis measurement. In addition, the confinement effect of n-octadecane inside the microcapsules also results in a significant decrease in both the melting and crystallization temperatures of the micro-PCMs.