Preparation And Thermoelectrical Performance Of Polyaniline Nanocomposites

Thermoelectric (TE) materials can be applied in thermoelectric power generators and Peltier coolers because of the direct conversion between thermal and electrical energy. The inorganic semiconductor as TE materials are used only in specialized area due to their low conversion efficiency, high cost and poor processability in thermoelectric system. Compared with inorganic semiconductor, conducting polymers possess several attractive features because of the low thermal conductivity and low cost derived from available resources and easy synthesis. However, the main obstacle for thermoelectric polymers is low electrical conductivity and the Seebeck coefficient. To improve the power factor, it is necessary to search an effective way to overcome these limitations.Conductive polyaniline (PANI) is considered as one of the most promising TE materials due to its structure diversification, environmental stability and unique doping/dedoping process. This thesis focused on the preparation and performance of polyaniline nanocomposites and put emphasis on researching on the influence of doping by protonic acids and nanocomposite on the TE performance of polyaniline. The main results are below:1. Emeraldine base form of polyaniline was synthesized by oxidative chemical polymerization. The polyaniline was doped by hydrochloric acid and camphor sulfonic acid, and the electrical conductivity and power factor increase with the protonic acids concentration increasing, which is attributed to the increase of carrier concentration.2. A novel and green mechanical cryogenic grinding method was employed to fabricatie nanostructured emeraldine based polyaniline/carbon nanotubes nanocomposite. The electrical conductivity as well as power factor of composites was found to be increased obviously with increasing CNTs content. The enhancement of the electrical conductivity should be attributed to the strong π-π interaction between π-bonded surface of the carbon nanotubes and the conjugated structure of polyaniline. The thermal conductivity still keep very low values with increasing CNTs content, which could be attributed to the phonon scattering effect of nanointerfaces produced by the nanostructure.3. The copper nano wires were prepared by a simple hydro thermal procedure. Then, polyaniline/copper nanowires composites were obtained through an in situ polymerization reaction and ultraphonic mixing method. The maximum electrical conductivity reaches1.5×103S/m at room temperature, which is higher than the conductivity of polyaniline doped with protonic acids.