Studies On Preparation, Structure, And Properties Of Functional Nanocomposites With Core-shell Structure

Nano science and technology will exert an important influence on social future development as a new developing front discipline. It is expected to apply to fields such as information, energy, environmental protection, medical science, manufacturing industry and national defense, etc. extensively.In the thesis introduction, starting at nano science and technology, the author has discussed nanomaterial, nanocomposite and hybrid materials, core-shell structured materials, and soluble magnetic nanomaterials sequentially. On this basis, the potential applications in biomedical fields and the significance of magnetic and luminescent nanocomposite with core-shell structure are discussed.In chapter 2, a simple method was developed to prepare highly water-soluble nanocrystal powders of magnetic iron oxides with different oxidation degree from magnetite (Fe3O4) to maghemite (γ-Fe2O3) coated with gluconic acid (GLA). Vibrational spectra (FTIR and Raman) were used to identify the products. Compared with FTIR, Raman spectrum analysis is a rapid, simple, and accurate method for identifying inverse spinel iron oxides. The coordination modes of GLA with surface Fe atom are confirmed, and the chemical stability and the high solubility of the products are explained.In addition, the cheap liquid paraffin is used as high-boiling-point organic solvent, and the oil-soluble magnetic iron oxides nanocrystals with particle size ca.5 nm are synthesized adopting the way of thermal decomposition of iron oleate in liquid paraffin. The above two types of soluble magnetic nanocrystals, water-soluble and oil-soluble, are adopted to fabricate Fe3O4@SiO2 core-shell structured magnetic nanocomposite using alcohol-water system and reverse microemulsion system respectively. The composite particle obtained by alcohol-water system has a core containing several magnetic nanocrystals, and that by reverse microemulsion system containing only one magnetic nanocrystal.In chapter 3, a new type of organic luminescent molecule which has a structure similar to core-shell structure, dendrimer, is summarized and studies in detail. In order to obtain high performance luminescent materials, a new europium complex [DMAP][Eu(TTA)4] is synthesized, and its molecular structure is confirmed by single-crystal structure analyse. The fluorescence spectra show that the strong red fluorescence is due to the dominant 5D0→7F2 transition. There is a strong excitation band in the 230-410 nm region which overlaps with the violet-blue wave band of visible light, and this make the complex suitable for application in the luminescent field which need visible light excitation.In chapter 4, the design principles of magnetic and luminescent nanocomposite suitable for biomedical fields are discussed. Aminopropyl triethoxysilane (APTES) is used to aminate the surface of Fe3O4@SiO2. The florescent molecule Rhodamine B is bonded with amino group, and the core-shell structured magnetic and luminescent nanocomposite is obtained. The product can emit yellow light excited by laser irradiation with a wavelength of 405 nm, but the luminescence efficiency is low. These achievements point out the direction for the further research.