Microfluidic fabrication and thermal properties of microencapsulated n-heptadecane with hexanediol diacrylate shell for thermal energy storage

An easy two-stage approach was proposed to prepare microencapsulated phase-change materials (MEPCMs) with n-heptadecane as the core and hexanediol diacrylate (HDDA) polymer as the shell in a co-flowing microfluidic device. The micromorphology and chemical compositions of the MEPCMs were investigated by scanning electron microscopy and Fourier transform infrared spectroscopy, respectively. The results showed that the shell of HDDA polymer was successfully fabricated upon n-heptadecane core. The obtained MEPCMs had regular spherical shape, smooth surface, and uniform particle size. The coefficient of variation in size was within the 2% limit. The thermal energy storage properties of the MEPCMs were investigated by differential scanning calorimetry. The results revealed that the MEPCMs with HDDA shell had good phase-change performance, high thermal-storage capability. The thermogravimetric analysis and thermal cycling test consisted with 100 heating/cooling processes were conducted to investigate the thermal stability of the MEPCMs. The results showed that the HDDA shell of MEPCMs was able to provide good protection for the core material of n-heptadecane. The excellent thermal stability of the MEPMCs was confirmed by the absence of n-heptadecane leakage. These advantageous properties make the MEPCMs with HDDA shell potential materials for thermal energy storage applications.