Preparation and Investigation of Hydrophobic Phase Change Microcapsules

Microencapsulation of phase change materials (PCMs) can undergo phase transitions to absorb and release heat avoiding the leakage of core materials which have important applications for printable materials with heat management. However, PCMs still face a severe challenge in the practical applications of water and moisture which accelerate its aging and degradation. In this study, we prepared hydrophobic microcapsules with eicosane as core materials by microencapsulation technology which used three monomers—acrylonitrile, methyl methacrylate, and methyl acrylate as wall materials with silica nanoparticles as dispersant. The silica-coated microcapsules were further modified using a hexadecyltrimethoxysilane (HDTMS) to realize the hydrophobicity. Fourier transform infrared spectroscopy (FTIR) and energy-dispersive X-ray spectroscopy (EDS) confirmed the successful synthesis of microcapsules with silica attachment on their surfaces. Scanning electron microscopy (SEM) observations and particle size analysis showed that the microcapsules exhibited regular, spherical morphologie with an average diameter of 54.88 μm. After that the phase change enthalpy of the hydrophobic PCMs was measured by differential scanning calorimetry (DSC) and the results indicated a significantly reduced phase change enthalpy compared to microcapsules without modification, showing more sensitive responses to ambient temperature changes. The water contact angle (WCA) of the modified microcapsules was 129.9° ± 5°, which satisfied the hydrophobic standard. The microencapsulation and modification of PCMs expand their applicability to a broader range of fields.