Preparation And Performance Of Polyaniline And It's Derivative Poly(2,3-dimethylaniline)

Polyaniline (PANI) has been considered to be one of the most promising electrochromic materials, due to its variety color changing, excellent cyclic reversibility, simple preparation technology, high chemical stability and low price of aniline (An) monomer, etc.Recently, the basal materials of electrochromic layer are usually those indium tin oxide (ITO) transparent conductive materials, which have several defects, such as low conductivity and the conductive layers are easy to be damaged. So, there is only a little PANI product with distributing inhomogeneous, if prepared directly on the ITO electrode.Therefore, in this experiment, we prepared polyaniline and poly(vinyl alcohol) (PANI/PVA) composite film by the electrochemical method on nickel substrate coated with PVA film previously. The electrochromic properties of the composite film coated on ITO conductive plastics were studied. The process optimization of the electrochemical preparation of PANI/PVA composite film was discussed through cyclic voltammetry and A C impedance tests. Results indicated that the highest electrical activity of the composite film was achieved when the mol ratio of SSA to H2SO4 was 1:1, the stirring rate was 200 r/min, the excitation voltage ranged from 1.10 V to 1.15 V with scanning 4 cycles and the working voltage ranged from -0.2 V to 0.8 V with scanning 20 cycles, respectively. Compared with the PANI film prepared directly on ITO conductive plastics, the PANI/PVA composite film showed better electrochromic properties.As an electrically conductive material with the highest values in commercial applications, another important use of PANI is anticorrosion additives used in the field of corrosion resistance of metal. PANI anticorrosive coating has several advantages such as special capability of scratches and pitting resistance, low cost, environmentally friendly, etc.. However, its applications have been greatly limited due to the high rigidity in the molecular chain backbone of PANI and the great interaction among molecules, which cause poor dissolubility and processability. Decreasing the rigidity of PANI chains and the interaction among molecular chains through ring substitution was believed as one of the most effective approaches for improving the dissolubility and processability of PANI. In addition, statistics suggested that the electronic-donating group substitution achieved more significant improvement in the corrosion resistance of PANI compared with the electronic-attracting group substitution.Accordingly, the poly(2,3-dimethylaniline) (P(2,3-DMA)) was polymerized in this study with 2,3-dimethylaniline (2,3-DMA) as the monomer, which is one of the electronic-donating group substitution derivatives of An, by using the solution method. Through the tests on the cyclic voltammetry, Tafel and the relative viscosity, the effects of the initiator (APS) dose, the dose of doped acid (HCl), the reaction time and the reaction temperature on the product properties were discussed, and the product structure was characterized through XRD, SEM, TGA and FT-IR. Results indicated that optimal indications for various macroscopic properties of the product were achieved when the molar ratio of APS to the monomer was 2:1, the molar ratio of HCl to the monomer was 1:1 at the reaction duration of 12 h and the reaction temperature of 25℃; besides, the results of comparative analysis on the structure and performance of the polyaniline emeraldine base (EB) indicated that the crystallinity and the thermal stability of P(2,3-DMA) somewhat decreased, but its dissolubility and corrosion resistance were improved significantly.