Preparation And Performance Investigation Of Vanadium Dioxide Intelligent Temperature Control Materials

There are many kinds of vanadium oxide that are vanadium pentoxide (V₂O₅), vanadiumdioxide (VO₂), vanadium trioxide (V₂O₃), mixed valence oxide (VnO_2n+1, VnO(2n-1)) and so on. V₂O₅ is a highly investigated material due to its great potentiality in a variety of applications ranging from use as cathode in solid state batteries, electrochromic devices, sensors, photocatalytic activities and supercapacitors. In laboratory testing, V₂O₅ nano-structure materials have been obtained through various methods such as sol gel, reverse-micelle, or quenching in water. However, their laboratory technologys have been difficult to be applied to industrial production.VO₂ as one of thermochromism materials, it has a phase transition temperature at near 68℃. It can change the infrared transmission reversible due to the crystal structure conversion when phase transformation occurs, this characteristic could be applies into intelligent temperature control films. So far the relevant researche focused on preparation and performance of the VO₂ inorganic films. However, the application of these films is limited, because the VO₂ film preparation technologies need expensive instrument and raw material, so that it is impossible for the industrialized large-scale production. Furthermore, VO₂ inorganic films are not steady in air. Therefore, the preparation of VO₂ inorganic and polymer composite film is the hottest area of ntelligent temperature-control films research. But there are some key technical problems that need to be solved such as powder size, to make the phase transition at room temperature occurs, the surface compatibility with polymer matrix etc.The primary contents, methods and results are as follows:1. Different shapes of V₂O₅ synthesized by the method of amine reaction. In heating conditions, V5+ compounds would be reduced by organic amine from V5+ to V4+.Different shapes of V₂O₅ could be prepared by heat-treatment of the complex precursor of organic amine and vanadium. The different shapes of V₂O₅ were investigated by X-ray diffraction (XRD), scanning electron microscope(SEM), transmission electron microscopy (TEM) The size of V₂O₅ superfine powders is in the range of 100～300 nm; the ply of V₂O₅ nanorods is near 100 nm;the length and ply of V₂O₅ cube are 0.5～2μm. NH₄V₄O₁₀ nanorods and (NH₄)₂V₃O₈ cube are prepared by hydrothermal with different pH.2. The room-temperature phase-transition VO₂ superfine powders have been preparation by amine reaction and molten doped. The fusion method was used to doped VO₂ effectively, then the phase transition temperature is reduced. The phase transition temperature of VO₂ is 27.8℃, when it is doped with 1at.% X。The room-temperature phase-transition VO₂ superfine powders have been analysised by XRD, DSC and SEM. It's phase-transition temperatures in 20～25℃, particle size is in the range of 100～300 nm.3. We study the modification method of VO₂ superfine powder preliminarily. Firstly, the surface of superfine powder has been activatied by dilute hydrochloric acid or sodium hydroxide solution. Next try to modifie its surface by stearic acid VO₂ composite films have been prepared with the substrate of acrylic lacquers. And the performance of the composite films has been preliminary studied by light test.