Polyurethane-Based Photo/Thermal Energy-Storage Capsules Made with Manganese Phtalocyanine as a Photothermal Agent

Photo/thermal energy-storage capsules with glyceryl monostearate based waterborne polyurethane as the shell, manganese phthalocyanine as the photothermal agent, and ethyl palmitate as the phase change material are fabricated. The compositions and morphologies of capsules are characterized by Fourier transform infrared spectrometer, field scanning electron microscopy, and laser particle size analysis. The encapsulation efficiency and phase change performances of capsules are investigated by thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC). The results show that the photo/thermal energy-storage capsules with spherical shape are successfully prepared. The TGA results show that the encapsulation efficiency of ethyl palmitate in capsules is above 82%, indicating manganese phthalocyanine has little effect on encapsulation of ethyl palmitate. The DSC results show that the small amount of MnPc in the core of the capsules suppresses the supercooling phenomenon of ethyl palmitate and has little effect on the enthalpy of capsules. Manganese phthalocyanine has strong absorption in the near-infrared region, and photo/thermal energy-storage capsules containing manganese phthalocyanine can convert light energy into heat energy. The heat energy is transmitted to phase change materials in the capsule, which store the energy via phase state changing. The results of thermal infrared image testing show that the prepared capsules have good photothermal conversion and energy-storage capacity.