Preparation And Properties Of Core Shell Hierarchical Structure

Core shell nanostructured functional materials have attracted tremendous interest becauseof their potential utilities in biomedical, catalytic, optical devices, molecular recognition,sensors and other fields. In addition, the nanoscale functional properties of core shellnanostructures are closely related to size, shape, and surface properties. A key challenge to theultimate exploitation of this class of novel nanomaterials is the development of abilities tocontrol the size, morphology and structure of the core shell structures. In this paper, ahierarchical magnetic titanate core shell structure and a hierarchical core shell Ag structureswere prepared by a template method. The effects on its structure, size, morphology andperformance were studied. The results achieved in this paper were listed as follows:1. Monodisperse hollow titanate microspheres with a porous shell were synthesizedthrough a template-hydrothermal method. The reaction times, tempretures and the proportionof TBT were systematic studied. These hollow microspheres exhibited a unique porousstructure, in which the nanotube hollow microsphere had a two-fold storage system includingthe cavity of the hollow sphere and the nanotube capability. Further, the microspheredemonstrated an improved controlled releasing performance that the cavity was capable ofgiving a fast releasing, while the channel of the nanotube showed a slow releasing property.This facile template-hydrothermal method could be a generally strategy to prepare hollownanostructures.2. A hierarchical double-shelled smart capsule composed of Fe3O4nanosphere core, and athin titanate nanotube shell had been successfully synthesized employing SiO₂spheres astemplates. The capsule with controlled internal cavity, shell composition and CdTe@mSiO₂quantum dots grafted on the nanotube for label. The unique three-dimensional hierarchicalarchitectures demonstrated a significantly improved property in drug targeted delivery, controlreleasing and fluorescence labeling. The magnetic nuclears showed a good magnetic response which could be used for the targeted drugs delivery. Because of the confined effect of thenanochannels in the hydroxyl-functionalized TiO₂shells, and the large surface area, test invitro showed that as-prepared capsules had a sustained-release property. Furthermore, with theCdTe quantum dot on TiO₂shell, the smart capsule exhibited a more extraordinary redluminescence property under UV irradiation, thus making the drug release be easily trackedand monitored.3. Ag@C core/shell nanoparticles were synthesized with a hydrothermal method. Theeffects of reaction temperature, time, and concentrations of silver precursor on finalnanostructures were systematically studied. The particle size and morphology of core shellstructure can be controlled by changing the content of glucose and silver nitrate. The presenceof competitivemolecules poly（vinyl pyrrolidone） was able to relieve the carbonization, andinhibit the growth of silver core. The Cshell shoews good surface reactivity which couldreduced Pt particles on the surface of core shell structure. It indicated their promisingapplications in optical nanodevices and biochemistry.4. Ag@SiO₂@Pt@TiO₂core shell nanoparticles were synthesized by a template method.The effects of the concentrations of reagents such as TEOS, H2PtCl6and TBT on the finalnanostructures were systematically studied. The hollow porous core shell Ag@Pt@Titanatemicrospheres were prepared by a hydrothermal reaction. The photocatalytic activity andstability of noble metal particles in the hierarchical nanostructure could be enhanced greatly.