The Research On Synthesis, Characterization And Application Of Graphite Oxide And Polypyrrole/Graphite Oxide Nanocomposites

Electrical conductive polymers/laminar inorganic materials nanocomposites have the advantages of mechanical, thermal, electrical conductive and electrochemical properties owing to nanometer level combination between polymers and laminar inorganic materials. It has become an attractive and new type of materials with wide application fields.The technology for preparing graphite oxide(GO)—one of the most focused laminar inorganic materials was explored in this dissertation.The influences of the content of graphite, the content of sodium nitrate, the time under low reactionary temperature, the content of potassium permanganate and the way of adding water under high reactionary temperature on the structure and properties of GO were investigated systematically. The technological conditions were determined. After preparing GO with high oxidation degree, we adopted GO as the intercalation host and polypyrrole (PPY) as the intercalation guest to prepare PPY/GO nanocomposites with the in-situ polymerization. The infulences of the kind of additives, the mass fraction of GO suspension, the molar ratio of sodium dodecylbenzenesulfonate (DBSNa) to py, the molar ratio of oxidant FeCl₃ and py, and the reactionary temperatire on the structure and properties of PPY/GO nanocomposite were investigated systematically. The electrochenmical performance of the PPY/GO nanocomposite used as the electrode of DNA biological sensor was explored firstly.The results of researches show that the oxidation degree of the product can be determined by XRD analysis and the determination of electrical resistivity during preparing GO from natural geaphite flakes with Hummers method. For the product of high oxidation degree,a sharp characteristic diffractive 001 peak of GO appears near 2θ=10°, the electrical resistivity reaches to 10² Ω m.The content of potassium permanganate is the main factor which influences the oxidation degree, but the influence of the conent of sodium nitrate on the oxidation degree is very small. The more the content of potassium permanganate, the less the content of graphite and the longer the time of oxidation under low temperature, the higher the oxidation degree of the product and the higher the electrical resistivity. Adding water continuously and controlling the temperature at about 100℃ during the high temperature reaction can obtain the stable GO. The raw material ratio and technological conditions for preparing GO with higher oxidation degree are: 10g of natural graphite flakes, 30g of potassium permanganate, 230ml concentrated sulfuric acid, 2hr of low temperature reactionary time and controlling the reactionary temperature within 100℃ by adding water continuously during high temperature reaction.