Fabrication and Performance of Polyurethane/Polyurea Microencapsulated Phase Change Materials with Isophorone Diisocyanate via Interfacial Polymerization

The polyurethane/polyurea microcapsules containing n-octadecane were prepared and modified by interfacial polymerization, where styrene maleic anhydride copolymer (SMA) was selected as emulsifier, polyurea based shell material was synthesized with isophorone diisocyanate (IPDI) and diethylenetriamine (DETA). Besides, polyethylene glycol 400 (PEG-400) was also added to form polyurethane shell and modify the microcapsules morphology. SEM images proved that with the modification of polyethylene glycol 400, the microcapsules morphology improved significantly. The microstructure of microcapsules under varying factors such as emulsification rates, DETA dropping rates and core/shell ratios were analyzed systematically. In particular, the equipments such as field emission scanning electron microscope (FE-SEM), different scanning calorimetry (DSC) and thermogravimetric (TG) were used to investigate the morphology, phase change properties and thermal stability of microcapsules. The DSC results verified the phase transition behavior of octadecane microcapsules, and microcapsules also displayed pretty thermal stability.