Preparation, morphology and thermal properties of microencapsulated palmitic acid phase change material with polyaniline shells

Novel microencapsulated phase change materials (MicroPCMs) in which palmitic acid (PA) acted as core material and polyaniline as shell material were prepared by in situ polymerization method without any emulsifier and doping agent. The effects of the preparation temperature, polymerization time, oxidant concentration and the acid dopants on the morphology and thermal properties of the MicroPCMs were investigated by field emission scanning electron microscope, differential scanning calorimetry and thermogravimetry. The results showed that spherical MicroPCMs could be obtained when the polymerization was initiated at a temperature higher than the melting point of PA with a medium oxidant concentration and then relatively slowly completed the polymerization at a low temperature without any acid dopant. The best preparation condition in this work was that the polymerization was initiated at 348 K for 2 h with the oxidant/aniline mole ratio of 0.75 and then completed at 303 K for 18 h. The prepared MicroPCMs showed spherical morphology with the phase change enthalpy of 106.3 J g(-1). Furthermore, the evaporation of PA in the MicroPCMs was postponed due to that PA was fully encapsulated in the capsules, which is favorable for its application.