Synthesis And Electromagnetic Studies On Polypyrrole-based Nanocomposites

As a novel class of composite material, Organic-Inorganic composite, with theexcellent properties possessed by nano-inorganic magnetic material and high polymermaterial, has become a hot spot in functional polymer material research area. It can beextensively researched in such areas as cell separation, Enzyme immobilization,isolation and purification of nucleic acids, and also enjoy increasing applicationresearch area in the organic and biochemical synthesis, environment/foodmicroorganism detection and so on.Polypyrrole (PPy) is known as an important class of conducting polymers, with thesame property of high conductivity, good chemical stability, low temperatureresistance and ease of preparation as that of other conducting polymers. Especially ithas the reversible doping mechanism making it one of the most promising conductingpolymers. It has potential applications in the multi-functional materials and devicessuch as: developing batteries, electrical and optical devices, sensor, ECD(electrochromic display device), and anti-corrosion materials, and so on. While thedisadvantages of PPy's insoluble refractory and hard to process greatly limit itsapplications. Researchers have already done a handful work in promoting mechanicalproperties of polypyrrole and processing performance. This thesis has prepared threekinds of PPy organic/inorganic composites with the PPy matrix, and also has done aseries of study on characterization of its properties. The main researches (majorfindings) are as follows:1. PPy/ Fe₃O₄ nanocomposite material is successfully synthesized with the methodof situ intercalation polymerization. And then its characterization are investigated indetail by means of such techniques as the analysis of transmission electronmicroscopy (TEM), scanning electron microscope (SEM), Fourier transform infraredspectroscopy (FTIR), thermo gravimetric (TG) and four probe meter and vibrationmagnetometer. As the results shown that ultrasonication not only makes thenano-Fe₃O₄ particles present more evenly which reduces the agglomeration in themagnetic particles , but also makes PPy aggregate in the surface of dispersednano-Fe₃O₄ particles as the growth point which improves the compactness of material. Meanwhile, with the introduction of nano-Fe₃O₄ the composite also have bettermagnetic property and lower the conductivity of composite to some degree. Moreover,the ultrasonic aggregation rules can alleviate the unpleasant phenomena, and nanocomposite with outstanding electromagnetic property can be prepared in this method.Nano-Fe₃O₄ and PPy are not simply covered physically and there may exist certaininteractions which improve the thermo stability of the composite materials.2. PPy/nano-Fe₃O₄/nanographite flake was synthesized by situ intercalationpolymerization. Its characterization and magnetic property were investigated in detailby some techniques such as Fourier transform infrared spectroscopy (FTIR), thermogravimetric (TG), transmission electron microscopy (TEM), Vibration magnetometer,Four probe meter (four point–probe method). Studies have shown that: nano-Fe₃O₄and graphite flake are uniformly present in the PPy matrix. Both the nano-compositeshave strong interactions with PPy, forming a stable ternary nano composite. Theconducting and magnetic results show that: adding the graphite flake in the PPymatrix can constitute good conductive network, thus improving its conductivity.Meanwhile the composite also have better magnetic property with the introduction ofnano-Fe₃O₄ and it can be widely used in the electro-magnetic field.3. In situ chemical oxidative polymerization of the PPy/Fe₃O₄/nano-silvercomposites, its composition and structure was characterized through Fourier transforminfrared spectroscopy (FTIR), thermo gravimetric(TG), Transmission ElectronMicroscope (TEM). And its electromagnetic property was tested with the four probemeter and vibration magnetometer. The results show that the introduction of nanoFe₃O₄, PPy/Fe₃O₄ binary composite owns better magnetic property with aconductivity reduction of the material to a certain extent. From the SEM it can findthe nano-silver particles with excellent conductivity, was evenly coated in the surfaceof PPy/ Fe₃O₄ composite, making the great enhancement in the conductivity of PPy/Fe₃O₄/nano-sliver composites much higher than that of the pure PPy and binarycomposite. Meanwhile the environment stability of ternary nanocomposites isobviously better than the pure PPy.