Preparation, Characterizations and Oxidation Stability of Polyethylene Coated Nanocrystalline VO2 Particles and the Thermo-Chromic Performance of EVA/VO2@PE Composite Film

摘要

In this study, an alternative approach is presented for developing thermo-chromic film, based on ethylene vinyl acetate copolymer (EVA) and vanadium dioxide (VO2) composite, with enhanced oxidation stability and compatibility. The neat monoclinic nanocrystalline VO2 particles were firstly prepared via a hydrothermal process, using citric acid as a reducing agent. After that, the synthesized VO2 particles were characterized, prior to mixing with maleic anhydride grafted PE. The crystalline structure, morphology and thermochromic performance of the polyethylene coated vanadium dioxide (VO2 @ PE) particles were then verified by SEM, TEM, DSC, XRD, FTIR techniques. After coating, a better oxidation stability of the VO2 particles was noted while the thermo-chromic performance of the VO2 @ PE was also maintained. After mixing with EVA, the percentage strain and tensile toughness of the VO2 @ PE based EVA films was the highest, followed by those of the uncoated VO2-based EVA films and the neat EVA, respectively. The VO2 @ PE-based films also maintained the thermochromic behavior of the monoclinic VO2. The above improvements were achieved at the expense of percentages of visible light transmittance and gel content of the EVA. This is the first report of the EVA/VO2-based thermo-chromic film, which is tougher and more stable toward oxidation than the prior state of the art. This composite film has the potential to be used as a kind of a specialty lamination material for smart windows and energy efficiency in buildings.