Deposition of conducting polymers

Sonoelectrochemistry has been employed in a number of fields such as in electroplating for the achievement of deposits and films of higher density and superior quality, in the deposition of conducting polymers, in the generation of highly active metal particles and in electroanalysis. Furtlienuore, the sonolysis of water to produce hydroxyl radicals can be exploited to initiate radical reactions in aqueous solutions coupled to electrode reactions. 

In Chapter 1 we explain the motivation and basic concepts of electrodeposition from ionic liquids. In Chapter 2 an introduction to the principles of ionic liquids synthesis is provided as background for those who may be using these materials for the first time. While most of the ionic liquids discussed in this book are available from commercial sources it is important that the reader is aware of the synthetic methods so that impurity issues are clearly understood. Nonetheless, since a comprehensive summary is beyond the scope of this book the reader is referred for more details to the second edition of Ionic Liquids in Synthesis, edited by Peter Wasserscheid and Tom Welton. Chapter 3 summarizes the physical properties of ionic liquids, and in Chapter 4 selected electrodeposition results are presented. Chapter 4 also highlights some of the troublesome aspects of ionic liquid use. One might expect that with a decomposition potential down to -3 V vs. NHE all available elements could be deposited unfortunately, the situation is not as simple as that and the deposition of tantalum is discussed as an example of the issues. In Chapters 5 to 7 the electrodeposition of alloys is reviewed, together with the deposition of semiconductors and conducting polymers. The deposition of conducting polymers... 

The more traditional approach has already been used in anodic electrocrystallization processes to produce nanocompositions and superlattices of mixed Ti-Pb oxides [341-347]. With HTSC materials, initial steps have been made in this direction in studies on the electrochemical deposition of conductive polymers on the surface of microband YBCO electrodes [28,50,433]. In the resulting composition, the reversible transition from the HTSC/metal junction (at the high doping degree of the polymer) to the HTSC/semiconductor junction has been achieved. The properties of these compositions allow one to control the shift over a wide interval. 

Although this sort of approach in the use of the direct mode has seen no further development, the lateral deposition of conducting polymers has been the subject of continuous and very successful research, in particular by Schuhmann and coworkers (8). Schuhmann realized that in order to deposit a conducting polymer locally, high concentrations of the radical cation of the monomer must be maintained within the volume between the UME and the substrate. Obviously, a constant potential applied to the substrate will cause the depletion of the monomer in the gap between the UME and the substrate and presumably the deposition of the polymer over the entire substrate. The solution was in the form of a series of potentials applied to the gold substrate. The first pulse was of 1.2 V versus Ag/AgCl for a time interval of 2 seconds, which caused the oxidation of nearly all the pyrrole monomers in the volume between the substrate and a 10 /xm Pt UME. Then... 

Z. Huang et al.. Selective deposition of conducting polymers on hydroxyl-terminated surfaces with printed monolayers of alkylsiloxanes as templates, Langmuir, 13, 6480, 1997. 

Due to its many applications for catalytic purposes [14], redox effects on M0O3 have been studied [15,16], by deposition of conducting polymer on its surface. Furthermore, taking into account that its sheets are separated by a van der Walls gap, lamellar M0O3 can be used as host species to produce intercalation compounds. 

The use of self-assembled monolayer formation has been adapted to the deposition of conducting-polymer nanofilms by the chemical polymerization of aniline at an amino-silane surface that acts as the seed layer for polymerization, which led to a more ordered nanofibrous growth than would be seen using bulk chemical polymerization [39]. This was shown to be capable of detection of 0.5 ppm ammonia vapor, with a... 

Deposition of conducting polymers on fiber surface of fabrics, such as cotton [37], bacteria cellulose (BC) [34], cellulose microcrystal [CMC] [38], cellulose derivatives [39] and alga [40] have been widely investigated in the last few years due to its importance in emerging technologies. These materials were generally obtained through in situ oxidative polymerization. 

Feedback-mode strategies have been reported for the deposition of conductive polymers. Heinze and coworkers coated the substrate with the water-insoluble monomer (2,5-bis(l-methyl-pyrrol-2yl)-thi-ophene) by thermal evaporation and polymerized it by generation of oxidants in aqueous solution by feedback SECM [184]. The substrate was then washed in organic solvent to remove the excess monomer. The polymerized patterns were insoluble and remained on the substrate. Wipf and Zhou deposited polyaniline onto noble metals by applying a positive potential to the substrate and consuming protons at the tip in order to locally shift the oxidation potential of the monomer to a value negative of the substrate potential [190]. 

Rozsnyai, L.E, and M.S. Wrighton. 1995. Selective deposition of conducting polymers via mono-layer photopatterning. Langmuir 11 3913. 

Habermuller, K., and W. Schuhmann. 1998. A low-volume electrochemical cell for the deposition of conducting polymers and entrapment of enzymes. Electroanalysis 10 1281-1284. 

Tallman, D.E., et al. 2003. Electron transfer mediated deposition of conducting polymers on active metals. Synth Met 135-136 33. 

Malinauskas, A. Chemical deposition of conducting polymers. Polymer, 42, 3957-3972 (2001). 

Rozsnyai, R. R, and Wrighton, M. S., Selective deposition of conducting polymers via monolayer photopatteming, Langmuir, 11, 3913-3920 (1995). 

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