Conducting polymers deposits

Hence, non-conducting polymers deposited on the top surface of Prussian blue-modified electrodes only slightly decrease sensor response, but dramatically improve both stability and selectivity of the transducer. 

The third method is to grow the polymer into its desired shape and form. An insulating polymer impregnated with a catalyst system is fabricated into its desired form. This is then exposed to the monomer, usually a gas or a vapour. The monomer then polymerises on the surface of the insulating plaslic producing a thin film or a fibre. This is then doped in the usual manner. A variation of this technique is electrochemical polymerisation with the conducting polymer deposited on an electrode either at the polymerisation stage or before the electrochemical polymerisation. 

Electronic transitions in thin films of conducting polymers deposited on the OTE have been investigated with UV-Vis spectroscopy. As an example, in Fig. 4.5, UV-... 

The electrochemical synthetic techniques of nanostructured conducting polymers are mainly carried out using galvanostat, potentiostat, and cyclic voltammetry (CV)- The advantages of electrochemical over chemical preparation are that the sizes of the nano-particles are easily controlled by the applied potential, current density, scan rate, and the number of cycles, and especially that the nanostmctured conducting polymer deposited on the electrode material can be directly used to investigate its electrochemical properties and in situ spectroelectrochemical characteristics. 

If species Z is present in large excess compared to O, then (17.2) is a pseudo-first-order reaction. To compare conveniently catalytic activity between the nanostructured conducting polymer and the bulk polymer, the key thing is that the amounts of the conducting polymer deposited on the electrode should be equal. The characteristics of the electro-catalytic reaction are related to the electrochemical techniques used. These characteristics are an increase in current density for potentiostat a shift in peak potentials for oxidation and reduction toward less positive potentials and more positive potentials, respectively, for galvanostat and an increase in the oxidation or reduction peak current, or a shift of the peak potentials of oxidation and reduction toward less positive potentials and more positive potentials, respectively, or both for cyclic voltammetry. 

Glass fibers have also been coated with conductive polymers. Deposition of polyaniline on glass-fiber fabric provided a method for the production of conductive fabrics [75]. The coating was achieved by several cycles of immersion of the fibers in an acid aniline solution followed by drying at 60°C and immersion in an oxidant solution. The mean growth rate of the deposit thickness was reported to be 150 nm per cycle. The conductivity of the coated fabrics reached 0.23 S cm. According to the authors, the adhesion of polyaniline to the substrate seems to be sufficient, since the mechanical properties of composites do not change in comparison to those of untreated fabric. 

Figure 20.23 (A) Schematic of a typical oCVD reactor. (B) Chemical structures of conductive polymer deposited by oCVD. PEDOT PPy, polypyrrole PTAA, poly(3-thiopheneacetic acid) [147], (With permission from Elsevier).

SECM has also been recently used to investigate the growth of conducting polymers deposited onto metal surfaces both chemically [73] and electrochemically [10] from solution. Our own interest in conducting polymers stems from their potential as alternatives to chromate conversion coatings for corrosion control of active metals and metal alloys. Specifically, we are investigating the use of hydroxybenzene sulfonates as electrochemical mediators for the electrodeposition of polypyrrole... 

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