Polymer films, scanning electrochemical conductivity

G. Wittstock, T. Asmus, and T. Wilhelm, Investigation of ion-bombarded conducting polymer films by scanning electrochemical microscopy (SECM). Fresenius J. Anal. Chem., 367, 346 (2000). 

Electrochemical polymerization is often used to prepare redox active polymer films on electrode surfaces (27). This technique has the advantage that a wide variety of conducting substrates can be used, and that film thickness can be directly controlled by the electrochemical potential scan rate, the potential range, polymerization time, and the choice of monomer concentration and electrolyte solution. 

Although conductive polymers can be made by a variety of methods, electropolymerization is by far the most convenient method in constructing a polymer modified electrode. The polymerization proceeds by an electrochemical reaction at the electrode surface, resulting in immobilization of a polymer film. For example. Figure 8.18 shows current-potential curves for electropolymerization of fluorene. The peaks in each curve show the deposition of an additional layer of polyfluorene (127). The peak currents during electropolymerization of different types of polymer can increase or decrease with each subsequent scan depending on the electron transfer characteristics of the polymer and the deposition rate (127, 128). 

Finally, Hapiot and coworkers used scanning electrochemical microscopy (SECM) in feedback mode to investigate electronic and permeation properties of the polymeric films obtained from the mono-substituted ZnOEPfbpy)" monomer and ZnOEP monomer in the presence of free bipyridine [143]. The results showed that the polymer obtained from the EPOP process (namely from the commercial ZnOEP) was more permeable and had a lower conductivity than the one prepared using the mono-substituted ZnOEPfbpy)" monomer. These two observations were... 

In order to immobilize enzymes in conducting polymers to fabricate biosensors, the electrochemical synthesis of polypyrrole films was studied under different conditions. It was found that the size and morphology of polypyrrole films synthesized using cyclic voltammetry were affected by the concentration of the supporting electrolyte at a scan potential range between 0.0 and 1.0 V (vs. SCE), and at a scan rate of 48 mV s [47]. The diameters of particles prepared in a solution containing 0.10 M pyrrole and 0.10 M NaCl... 

Over recent years, internal reflectance infrared studies have tended to concentrate on the study of relatively thick films of conducting polymers or layers, (see, for example, the work of Pham and coworkers [49, 50], or Kvarn-strom, Nauer, Neugebauer and coworkers [51-54]) in which sensitivity was not a particular problem, or on the semiconductor-electrolyte interface, (see the work of Chazalviel and coworkers [35, 40, 41]), in which the SPP excitation approach is not appropriate. However, interest has focused again on this phenomenon with the surface-enhanced infrared absorption spectroscopy (SEIRAS) studies of Osawa and coworkers [19, 26, 27, 46, 55, 56], who have combined the application of the Kretschmann configuration with step-scan FTIR spectroscopy to study fast, reversible electrochemical processes on timescales down to microseconds [26, 46, 57-60]. 

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