Fabrication and characterization of microencapsulated phase change material with low supercooling for thermal energy storage

Microencapsulated phase change material with a low supercooling degree is one of the increasing important researches as well as industrial application for thermal energy storage. This study develops a novel and low supercooling microencapsulated n-octadecane (MicroC18) with n-octadecyl methacrylate (ODMA)–methacrylic acid (MAA) copolymer as shell using suspension-like polymerization. The fabrication and properties of MicroC18 were characterized by using a field-emission scanning electron microscope (FE-SEM), Fourier transformed infrared spectroscopy (FTIR), particle size distribution analysis, differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA). The MicroC18 with spherical shapes and an average diameter of 1.60–1.68 μm are fabricated. The onset crystallizing temperatures of MicroC18 are only 4 °C below that of n-octadecane. The unique copolymer shell has a significant impact on the low supercooling of MicroC18. The n-octadecane in all of the samples crystalizes by heterogeneous nucleation. The content of n-octadecane in the microcapsules is low; however, the microcapsules still exhibit high enthalpy through the contribution of the shells. At a monomers/n-octadecane mass ratio is 2:1, as used in the recipes, the MicroC18 with highest phase change enthalpy was obtained. The temperature of thermal resistant of MicroC18 is approximately 235.6 °C, which is affected by the thickness of the polymer shell.