Preparation Of Polyaniline And Its Derivatives-based Composites And Their Application In Electrochemical Analysis

In recent years, polyaniline (PANI) and its derivatives-based composites have received a great deal of attention because of their excellent catalytic performance in sensors. Based on the advantages of composites, in this thesis, the preparation of polyanilne and its derivatives-based composites and their application in electrochemical analysis were studied. The main contents of the thesis are as follows:(1) Acrylic acid was first electropolymerized on the surface of a gold electrode. Then, PANI was electrodeposited on the poly(acrylic acid) (PAA) network to give a PANI-PAA composite film. Electrochemical studies confirmed the formation of PANI-PAA composite which exhibited excellent electroactivity over a wide pH range. The electro-oxidation of ascorbic acid (AA) was studied in detail. The modified electrode exhibits significantly reduced oxidation overpotential. The response towards AA is linear in the range of 1.0×10-6～9.3×10-3 M at a potential of 0.1 V. The sensitivity is 207μA·mM-1·cm-2, and the detection limit is 1.0μM. Interferences by uric acid and dopamine are negligible. The electrode thus enables sensitive and selective determination of AA, with a performance superior to many other PANI-based ascorbate sensors.(2) Polyaniline (PANI), polyaniline doped with poly(styrene sulfonate) (PANI-PSS), polyaniline doped with gold (PANI-Au) as well as polyaniline co-doped with poly(styrene sulfonate) and gold (PANI-Au-PSS) have been prepared using the interfacial polymerization method. Electrochemical techniques were used to study their electrochemical and electrocatalytic activities. With the pH values increasing from pH 6.98 to 9.18, PANI-PSS and PANI-Au-PSS exhibit much better electrochemical activity than PANI and PANI-Au, indicating that PSS plays a vital role in improving the electroactivity of PANI in neutral and basic solutions. The doping of Au alone with PANI is not the same effective as the PSS in the enhancement of electrochemical and electrocatalytic activities, whereas the co-use of Au and PSS has a synergistic contribution on the improvement of electrocatalytic activity of PANI, and therefore the ternary PANI-Au-PSS composite exhibits the strongest electrocatalytic ability.(3) Poly(o-aminobenzoic acid) (PoABA) was first electrodeposited on the electrode surface, then the copper ions were adsorbed into the resulting PoABA film, and the adsorbed copper ions were further reduced by hyrazine hydrate to obtain PoABA-Cu composite modified eletrode. The PoABA-Cu modified eletrode displayed good current response to hydrogen peroxide with a linear range of 5x10-5～1×10-2 M and a sensitivity of 96μA·mM-·cm-2.(4) Poly(o-phenylenediamine) and copper composite was synthesized by the direct reaction between o-phenylenediamine monomers and copper ions, and characterized by SEM, UV-vis adsorption spectroscopy and Fourier transform infrared spectroscopy (FT-IR). The composite-modified electrode has good electrocatalytic ability to hydrogen peroxide with a linear range of 2x10-5～5x10-3 M and a detection limit of 4.0μM.