The Synthesis And Characterization Of Polyaniline Nanofibers

Polyaniline has extensive application prospect with many excellent properties. In this article, a chemical method was used for synthesis of polyaniline nanofibre with toluene-p-sulfonic acid (p-TSA) as a doping reagent of H+ and nano Nd2O3 as a revulsant.The critical micelle concentration (CMC) of p-TSA aqueous solution, electrokinetic potential (Zeta potential) of Nd2O3 colloidal particles in 0.206 mol·L-1 p-TSA aqueous solution and electrical conductivity of the polyaniline nanofibres were measured. SEM, FT-IR, XRD and ICP methods were used to research the effect of concentration of p-TSA aqueous solution and Zeta potential of Nd2O3 in p-TSA aqueous solution on the micromorphology and structure of polyaniline nanofibres. Pt electrodes modified by the nanofibres film (expressed as PANI/Nd2O3/Pt) were prepared through the method of in-situ polymerization. Cyclic voltammetry (CV) was used to study the electrochemical activities of PANI/Nd2O3/Pt in H2SO4, H3PO4 and HCl aqueous solution.The experiment results showed that the CMC of p-TSA was 0.004 mol·L-1. Zeta potential equals to zero if the molar ratio of p-TSA to Nd2O3 (expressed as np-TSA:nNd2O3) equals to 1:0.17 in the polymerization system. Polyaniline nanofibres, with 100-200 nm in diameter and less agglomerating phenomenon, could be synthesized under the conditions as below:the concentration of p-TSA outclassed the CMC value, np-TSA:nNd2O3 value was bigger than 1:0.17, the molar ratio of aniline monomer to ammonium persulfate was 1:1, polymerization temperature was 20℃, and polymerization time was 16h. Under the molding pressure of 10 MPa, the electrical conductivity of the nanofibres at room temperature was 0.1 S·cm-1. The existing of Nd2O3 in the polymerization system could promote the forming of polyaniline nanofibres. As a kind of impurity,0.02% Nd existed in the amorphous polyaniline nanofibre. There was no new characteristic peaks in FT-IR spectrum of the polyaniline, however, all the peaks showed a blue shift with different degrees. These indicated that no chemical interaction existed between polyaniline molecular chain and Nd2O3.CV experiments results indicated that when the peak current density of oxidation reached to the maximum, the kind and concentration of the acids were 1.0 mol·L-1 H2SO4,2.0 mol·L-1 H3PO4 and 0.75 mol·L-1 HCl. Comparing the three acids, the electrochemical activity of the electrode was the best in 0.75 mol·L-1 HCl aqueous solution. The polyaniline nanofibre material did not degradate in the H3PO4 and not distinctly in H2SO4, but the degradation was obvious in HCl aqueous solution.