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This work presents the electrochemical synthesis and characterization of 3-substituted thiophene conducting copolymers suitable for applications in electrochromic displays. The 3-methoxythiophene (MOT), 3-thiophenemethanol (TM), 3-thiopheneethanol (TE) and 3-thiophenecarboxylic acid (TCA) monomers showed oxidation potentials at 1.1, 1.5, 1.5 and 1.8 V/SCE, respectively. Copolymers containing MOT (PMOT-co-TE, PMOT-co-TM and PMOT-co-TCA) were synthesized by oxidative electropolymerization and characterized by GPC, FTIR, UV–vis and cyclic voltammetry. The copolymers were found to be soluble in acetonitrile, N,N-dimethylformamide and N,N-dimethylsulfoxide. PMOT, PMOT-co-TE and PMOT-co-TCA showed a dependence of the anodic potential on the scan rate and a quasi-reversible profile. PMOT-co-TM showed an irreversible electrochemical profile. PMOT and PMOT-co-TE were the most electroactive polymers. The oxidation potentials vs. SCE of PMOT, PMOT-co-TE, PMOT-co-TM and PMOT-co-TCA were 0.22, 0.30, 1.16 and 0.20 V/SCE at 50 mV s −1 , respectively. The copolymers deposited on ITO showed reversible color variation between blue in the oxidized state to orange when reduced, demonstrating their potential for electrochromic applications.

The 3-octadecylthiophene has been synthesized and characterized by FTIR, UV–vis and 1 H and 13 C NMR. The correspondent polymer, the poly(3-octadecylthiophene) (PODT) has been chemically and electrochemically synthesized. The obtained polymer is soluble in common organic solvents, such as chloroform, tetrahydrofuran and toluene. IR and NMR spectra analysis confirm its regio-regularity. The electrochemical properties studied by cyclic voltametry of PODT electrochemically synthesized were characterized by a semi-reversible behavior with one anodic peak at 0.96 V and one cathodic peak at 0.77 V vs. Ag/AgNO 3 . Spectroelectrochemistry and optical properties, such as optical absorption and photoluminescence (PL) were studied at different temperatures for the PODT chemically synthesized. Spectroelectrochemical results clearly indicate the polaron formation. The results obtained from the analysis of the dependence on temperature of the optical properties of the PODT casting film corroborate the high regio-regular structure of the chains.

Heterogeneous blends of a soluble substituted polyaniline, poly(2,5-dimethoxy aniline) (PDMA), and two fluoropolymers, poly(vinylidene fluoride) and poly(tetrafluoroethylene- co -vinylidene fluoride- co -propylene) were prepared by casting. The use of this ternary system allowed the compatibilization of the polymer mixture and the improvement of the adhesion to the substrate of stainless steel. Three compositions with increase content of PDMA were investigated and compared with PDMA coating behavior. The superficial composition of the coatings was characterized by wide-scan X-ray photoelectron spectroscopy, which indicated that the steel surface is totally covered by the polymers. Chronopotentiometry at zero current systematic study was used to determine the open circuit potential (OCP). After 7 days immersion in saline solution, PDMA and the three blends showed similar OCP values of −170 mV (reduced state), which is shifted to more positive values in relation to the bare steel. Electrochemical impedance spectroscopy was used to characterize the polymeric coatings in the absence of active corrosion at the metal/coating interface. The blends showed higher R ct compared to PDMA (10 2 –10 3 times) and this result was interpreted as a contribution of barrier of fluoropolymers. Salt spray test was used to evaluate the corrosive resistance of coatings and blends in aggressive conditions during 1000 h. Energy dispersive spectrometer semi-quantitative chemical analysis was performed on the coatings after the test and indicated that blends show superior resistance to the fog test in relation to the PDMA coating. Therefore, the blends PDMA/fluoropolymer behave as an electrochemical barrier as well as a physical barrier showing superior corrosion inhibition in relation to PDMA.

Cyclic voltammetry and electrochemical quartz crystal microbalance techniques were combined to study the ionic exchange process in polypyrrole doped with the anionic surfactant, dodecylbenzenesulfonate. A quantitative analysis of the results indicates a doping degree of 20% after electropolymerization. Studies performed in monomer-free solutions show that both anions and cations of the electrolytes play an important role in the redox process. Quantitative calculations also take into account the transfer of neutral species like solvent molecules.

Cyclic voltammetry and optical beam deflection (OBD) techniques in different electrolytes, KCl, KClO 4 , CsCl, NaCl, LiClO 4 and LiCl, were used to study the ionic exchange processes in polypyrrole (PPy) doped with an anionic surfactant, dodecylbenzenesulfonate (DBS − ). Our results show the role played by the cations during the first redox process of the polymer. To compare the OBD curves in each electrolyte, they were normalized with respect to their dependence on the chemical nature of the electrolyte. The use of temporal convolution, proposed by Vieil et al. ( J. Electroanal. Chem., 368 (1994) 183), to relate electrical current and angular optical beam deflection, allows the modeling of the OBD curves and the calculation of apparent diffusion coefficients for each electrolyte and the diffusion coefficient of each ionic species.

In situ laser beam deflection measurements (mirage spectroscopy) during cyclic voltammetry have been carried out in order to study ionic movements in eutectic NH 4 F;2.3HF during the first and second redox processes of polyaniline, poly(0-methylaniline), poly(0-ethylaniline) and poly(0-propylaniline). The results outline the predominant role of anions in the redox mechanism (doping process) of these conducting polymers.

This study is devoted to the comparison of Cyclic Linear Sweep Voltammetry curves obtained for an electronic conducting polymer, the polyaniline, and curves obtained from a mathematical model. Our model is based on the following assumptions : - reversible, quasi-reversible or irreversible charge transfer - electrostatic or mechanical interactions within the electroactive polymer in order to explain the abnormal width of voltammetric peak of these materials [1–3] - variable capacitance to explain the polymer's capacitive behaviour [4] - variable conductivity to explain the shape of the voltammograms of such polymer [5–7] - Steady-state hysteresis which is taken into account by different values for the formal redox potential between forward and reverse scans, together with a slight dependence of the conductivity with the current direction.