Electropolymerization functionalized conducting polymer

Meanwhile, the R-R coupling (see Sect. 2.2) has evidently found general acceptance as the main reaction path for the electropolymerization of conducting polymers The ionic character of the coupling species explains why polar additives such as anions or solvents with high permittivity accelerate the rate of polymerization and function as catalysts. Thus, electropolymerization of pyrrole is catalyzed in CHjCN by bromide ions or in aqueous solution by 4,5-dihydro-1,3-benzenedisulfonic acid The electrocatalytic influence of water has been known since the work... 

Moreover, 0.5-pm diameter MIP beads have been prepared for chronoamperometric determination of morphine [204]. These beads were synthesized by thermo-radical precipitation polymerization of the MAA functional monomer, TRIM cross-linker, AIBN initiator and morphine template in the ACN solution. Then the beads were immobilized in a film of the PEDOT conducting polymer, electropolymerized onto the ITO electrode. The morphine detection with the use of the resulting chemosensor was much more sensitive to morphine (41.63 pA cm 2 mM for the morphine concentration range of 0.1-2 mM) than to morphine analogues. LOD for morphine was 0.3 mM. 

In addition to catalysis of small molecule transformations and biocatalysis, non-functionalized LLC phases used as reaction media have also been found to accelerate polymerization reactions as well. For example, the L and Hi phases of the sodium dodecylsulfate/n-pentanol/sulfuric acid system have been found to lower the electric potential needed to electropolymerize aniline to form the conducting polymer, polyaniline [110]. In this system, it was also found that the catalytic efficiency of the L phase was superior to that of the Hi phase. In addition to this work, the Ii, Hi, Qi, and L phases of non-charged Brij surfactants (i.e., oligo(ethylene oxide)-alkyl ether surfactants) have been observed to accelerate the rate of photo-initiated radical polymerization of acrylate monomers dissolved in the hydrophobic domains [111, 112]. The extent of polymerization rate acceleration was found to depend on the geometry of the LLC phase in these systems. Collectively, this body of work on catalysis with non-functionalized LLC phases indicates that LLC phase geometry and system composition have a large influence on reaction rate. 

Different examples of hydrogenation of organic molecules with conducting polymer modified electrodes have been described rather recently in the literature. Two different kinds of modification have been considered for this application insertion of metallic particles, and functionalization of pyrrole with transition metal complexes leading, after electropolymerization, to active electrodes. 

Figure 14.1 Template-directed synthesis of conducting-polymer nanowires. Nanowires of PPy were synthesised by electropolymerization within an alumina template structure with a gold electrode base (A,B). Nanowires could be further functionalized by the growth of additional species such as nickel and gold (C). (Reprinted with permission from Electroanalysis, Magnetically Assembled Multisegmented Nanowires and Their Applications by M. A. Bangar, C. M. Hangarter, B. Yoo et al., 21, 1, 61-67. Copyright (2009) Wiley-VCH)...

The main difficulties related to electropolymerization processes have been ruled out, and theoretically, no metal specificity is involved in the procedure which could restrict the application, except the case of PANI whose acidity properties can conflict with different metal oxides, as previously stated in Section 16.2. The main problem lies in the fact that all the conducting polymers are generally insoluble and, therefore, mixing them with paint will involve either the fabrication of particle dispersions or functionalization of the polymer in order to make it soluble in an organic solvent. Initially centred on PANI formulations, the process has been progressively extended to other conducting polymers like PPy, PT, and their derivatives. 

In vivo biosensors for glucose based on derivatized conducting polymers were also pursued. Yasuzawa et al. [64] synthesized pyrrole monomers that were derivatized with the phosphotidylcholine group to function as hemocompatible biosensors. This moiety is the principal component of the outer leaflet of red blood cell membranes. Subsequent electropolymerization of the pyrrole derivatives in the presence of glucose oxidase formed the outer bioactive coating of a glucose biosensor that also contained an inner membrane of Nafion. The combination of these membranes resulted in enhanced selectivity and retention of enzyme activity. 

Figure 8.10. Example of N-functionalized electropolymerizable pyrrole units leading to pre-doped electronically conducting polymers used for post-electropolymerization incro-poration of pophyrin derivatives.

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