Preparation and thermal characterization of n-octadecane/pentafluorostyrene nanocapsules for phase-change energy storage

A novel class of nano-encapsulated phase-change material (NEPCM) was produced using the suspension polymerization method with the core n-octadecane capsulated in the shell of poly(2,3,4,5,6-pentafluorostyrene). The morphology and components of the NEPCM were analyzed by the scanning electron microscopy, the X-ray diffractometer, and the Fourier-transform infrared spectroscopy. The thermal performance of various NEPCM samples was compared based on the measurements of the differential scanning calorimetry, the thermogravimetric analyzer, and the thermal conductivity meter. It is found that the NEPCM4 with shell/core mass ratio 1:2 has the best thermal performance among the tested samples with six different mass ratios. The measured melting enthalpy heat of (171.8 ± 2.2) J•g−1 for the NEPCM4 is the highest among all the tested capsules and the encapsulation efficiency for the NEPCM4 is also maximized at (76.1 ± 1.8)%. Capsule size variation in the prepared samples is small. The average size diameter of the NEPCM4 capsules is measured to be 490 ± 16 nm. The thermogravimetric investigation reveals that the initial weight-loss temperature for the NEPCMs is increased in comparison with that for the pure n-octadecane. The prepared nanocapsules exhibit excellent thermal stability and thermal properties, possessing enormous potentials to enable practical applications in thermal energy storage.