Preparation of Polyurea Microcapsules Containing Phase Change Materials Using Microfluidics

The polyurea microcapsules containing phase change materials (MicroPCMs) are prepared by using a simple microfluidic device at low temperature. Paraffin is the core material, and isophorone diisocyanate (IPDI) and tetraethylenepentamine (TEPA) are the shell materials. Effects of the flow rate of each phase, the emulsifier type, and the emulsifier dosage on MicroPCMs are investigated systematically. The size of MicroPCMs can be controlled by changing the flow rate of each phase. Fourier transform infrared spectroscopy (FT-IR) and scanning electron microscope (SEM) are used to characterize the chemical structure and morphology of the MicroPCMs, respectively. The images of SEM show that MicroPCMs have the regular spherical shape and a good size distribution. The results of FTIR indicate that MicroPCMs have been successfully prepared as the characteristic peaks of paraffin and polyurea are observed in the curve of MicroPCMs. The thermal properties and stabilities of MicroPCMs are investigated through differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA). When taking sodium dodecyl sulfate (SDS) as the emulsifier, the results show that the latent heat is 87.5 J/g with an encapsulation efficiency of 96.5% and the appropriate dosage of SDS is 1.0 g for synthesizing MicroPCMs. The results of TGA present that the polyurea shell can prevent the leakage and volatilization of the paraffin.