Synthesis And Characterization Of Polyaniline Core - Shell Nanoparticles And Carbon Nanoparticles

Core-shell nanostructures is the most simple two-component systems, including an internal nanoparticles encapsulated in a different material. Compared with the traditional one-component system, complex multicomponent systems both have challenges and opportunities. The core-shell nanocomposites formed by metal nanoparticles and conducting polymers have attracted much attention in recent years. These complex systems are expected to pose synergistic properties between the metal nanoparticles and the polymers, making them to be the potential candidates for future applications.Because polyaniline has excellent environmental stability, synthetic raw materials are cheap, synthesis method is simple, and polyaniline both shows excellent electrochemical performance, the electromagnetic wave absorption performance and high electrical conductivity, so since the polyaniline was found, polyaniline has become one of the fastest growing and the most studied conducting polymers.Carbon nanoparticles are a new type of carbon nanomaterials, since it has a lot of excellent properties, such as continuous and wide excitation spectrum, tunable emission wavelength, good biocompatibility, low toxicity, low molecular weight and particle size. So the carbon nanoparticles have been paid a lot of attention since it was found. In addition to the above advantages, carbon nanoparticles also have many good properties, such as electroluminescence, chemiluminescence, upconversion characters, photoelectric charge transfer characteristics and so on, which makes carbon nanoparticles can be used in luminescent materials and the preparation of nanocomposite materials and many other fields. Because of the excellent fluorescent properties, good biocompatibility and low cytotoxicityof carbon nanoparticles, they tended to replace semiconductor quantum dots which have serious toxicity in the biochemical analysis detection and bio-imaging.Fluorescent carbon nanoparticles, as the new fluorescent nanomaterials, have showed great potential applications in the fluorescent ink, photoelectric device, and catalytic technology.The thesis consists of two parts:review and research work. The review simply introduces the properties, synthesis methods and application of the polyaniline, the importance of studying core shell system, and the preparation methods of core-shell nanomaterials. The properties and applications of carbon nanoparticles also are introduced. Finally, the research purpose and content of the thesisare elaborated.The second part is research work, mainly included two parts:1. Synthesis and characterization of Au@PANI core-shell NPs.In this work, we synthesized the gold@polyaniline core-shell nanoparticles by chemical oxidation. By changing the experiment condition, we found that in the solution containing the citrate-stabilized gold nanoparticles, with aniline monomers as the raw material, sodium dodecyl sulfate and polyethylene pyrrolidone both as surfactant,30%hydrogen peroxide as oxidant, Au@PANI core-shell NPs containing two components was synthesized successfully. The as-synthesized NPs were characterized by TEM, UV-vis spectrum, FTIR spectrum, and cyclic voltammetry. The cyclic voltammetric results showed that the electrochemical activity of polyaniline has improved by parceling the gold nanoparticles into the polyaniline nanoparticles. The reason is that gold nanoparticles can move freely in the hollow shell, so every surface of gold nanoparticles to expose, makes the full use of its catalytic activity.2. Synthesis and characterization of S and N co-doped carbon NPs. In this work, carbon nanoparticles were synthesized by pyrolysis at higher temperature in oil amine and oleic system. Several carbon sources, including anhydrous citric acid, cysteine, the mixture of anhydrous citric acid and cysteine, and the mixture of anhydrous citric acid and glycine, were investigated. The results indicated that the carbon nanoparticles from the mixture of anhydrous citric acid and cysteine showed the best properties and the highest fluorescent quantum yield, which maybe results from the co-dopingof nitrogen and sulfur in carbon.And we found that as the excitation wavelength and carbon nanoparticles concentration changes, the intensity and location of the fluorescence emission peak also changed, this may because that there exist two luminous sites in carbon nanoparticles.