Intercalation, Form Film And Slow-release Performance Study Of LDHs Hybrid-materials

The structure of layered double hydroxides (LDHs), main properties, preparation methods and applications of LDHs were summarized in this chapter. The intercalation of cinnamic acid (CA) into LDHs had been synthesised by the delamination/reassembling method and its physical and chemical properties were studied. A-naphthaleneacetate (NAA) was intercalated into the layered double hydroxides Mg/Al-NO3-LDH by ion-exchange method. And we got the films formed by the layer-by-layer self-assembly method with polymers and LDH, and the release of mechanism was also studied.(1)The Mg/Al-NO3-LDHs was obtained by the hydrothermal method and was delaminationed in the Formamide. The intercalation of CA into LDHs by the delamination/reassembling method has been investigated. The obtained intercalation compounds were characterized by XRD, FT-IR, TG-DSC, UV techniques. The results show the method can successfully got the intercalation compound. From the XRD data, the compound has complete structure and single crystal, and the distance of LDHs was expanded. FT-IR reveal that the presence of force between the plate of layers and the anion in addition to electrostatic forces and also have hydrogen bonding forces such as van der Waals force. The results of TG-DSC indicate that the thermal stability of materials was increased, and also show the complex system of supermolecular between the host-guest intercalation. The UV absorption range and ability of the intercalation compound are also changed.(2) The Mg/Al-NO3-LDHs was obtained by the coprecipitation method, and NAA was intercalated into the layered double hydroxides Mg/Al-LDH by ion-exchange method. And we prepared the films by the method of layer-by-layer self-assembly with cationic polyacrylamide, polyacrylic acid sodium and LDH. From the datas of XRD, FT-IR, SEM, it was proposed that the NAA anions were accommodated in the interlayer region as a bilayer of species with the carboxyl attaching to the upper and lower layers, and also shows that Mg/Al-NAA-LDH was absorbed on the quartz glass.(3) The release mechism of the film was discussed. The film was putted into various solutions, and the release of NAA from the film showed obvious release effect compared with the powder. The mechanism of the NAA released behavior fitted to the first-order kinetics, and the process of release may be controlled by the dissolution of film and ion-exchange with various ions in the solution.