Fabrication Of Polypyrrole Nanomaterials And Nanocomposites By One-step Approach And Their Catalytic Properties

Polypyrrole and its nanocomposite materials with nanostructures,especially those with controllable size and morphology is attracting theresearch interest of the majority of scientists, because of their potentialapplications in absorption, separation, drug delivery, detection, andenvironmental research areas. Polymer nanomaterials are mainly preparedthrough multi-step method. Firstly, template is synthesized and thepreparation of polypyrrole nanomaterials is in-situ polymerizationmethod, but this method is relatively more complicated. Currently, thereare many ways to prepare polypyrrole hollow nanostructure, but thepreparation of polypyrrole nanomaterials with controllable morphology isstill a huge challenge. Nanocomposites generally is a compositecontaining two or more nanocomponents. In recent decades, people have synthesized polypyrrole nanocomposites mainly by multi-step methods.The first process is preparing a conducting polymer nanostructures, andthen metal or metal oxide nanoparticles grow on its surface. However, thepreparation of polypyrrole nanostructures with controllable morphologyand their nanocomposites with metal nanoparticles uniform dispersing inthe ternal and on the surface of nanostructures by a one-step approach isstill a great challenge.In this thesis, polypyrrole nanomaterials and nanocomposites havebeen prepared by a one-step approach. We have succeeded in thepreparation of polypyrrole hollow nanocapsules and polypyrrole hollownanotubes, and the product could be prepared in on a large scale. For thepreparation of PPy nanocomposites, we have successfully preparedPPy/Pd composite nanocapsules and GO/PPy/Pd composite nanosheetsby a one step approach. Pd nanoparticles are highly distributed on thesurface of these two nanomaterials with uniform size. The obtainedPPy/Pd composite nanocapsules and GO/PPy/Pd composite nanosheetsexhibit excellent catalytic activities towards the reduction ofp-nitrophenol at room temperature.1. We afforded a simple one-step approach to prepare PPy nanocapsulesand nanotubes in aqueous solution via chemical an oxidationpolymerization approach. In a typical reaction in the presence of high concentration of RB (10mM), the wall thickness of the PPy capsules wasin the range of30-50nm. While when the reaction was performed in thepresence of1.25mM RB, fiber-like PPy samples were prepared. Hollowtubular structures with outer diameters and thickness in the range of180-280nm and20-30nm were obtained, respectively. This process forfabricating hollow PPy nanostructures does not require removal of thetemplate, allowing easy production on a large scale.2. We afforded a facile one-step redox polymerization method for thepreparation of highly dispersed palladium (Pd)/polypyrrole (PPy)nanocapsules. During the polymerizaion process the formation ofRB-PdCl2-4complex via an electrostatic interaction plays a key role forthe preparation of Pd/PPy composite nanocapsules. The well-dispersedPd nanocrystals with small sizes of2-4nm embedded in PPynanocapsules exhibited a good catalytic activity during the catalyticreduction of p-nitrophenol into p-aminophenol by NaBH4in aqueoussolution. The kinetic apparent rate constant(kapp) was about8.87×10-3/s.Moreover, the as-prepared Pd/PPy composite nanocapsules exhibited agood reusability, which could be repeatedly used for the reduction of p-nitrophenol with a high catalytic activity for at least10successivecycles.3. We afforded a facile one-step redox polymerization method for the preparation of highly dispersed GO/PPy/Pd composite nanosheets. Thesize of Pd nanoparticles was about5nm, which was well uniformdispersed on the surface of GO/PPy composite nanosheets. TheGO/PPy/Pd composite nanosheets showed a good catalytic activity forthe reduction of p-nitrophenol into p-aminophenol by NaBH4in aqueoussolution. The kinetic apparent rate constant(k-3app) was about31.73×10/s,which showed that the catalyst has high catalytic activity due to largespecific surface of GO and the fast electrons transfer in Pd/PPy/GOnanosheets.