Electropolymerized Thin Films

Electropolymerized thin films of Zn(II)-4,9,16,23-tetraaminophthalocyanine immersed in a solution of relatively high pH have been studied using electrochemistry and spectroelectrochemistry [483]. 

F. Palmisano, R. Rizzi, D. Centonze and P.G. Zambonin, Simultaneous monitoring of glucose and lactate by an interference and cross-talk free dual electrode amperometric biosensor based on electropolymerized thin films, Biosens. Bioelectron., 15(9-10) (2000) 531-539. 

Next, in the 1980s, the organic multilayer structures, which are another key technology of present high-performance OLEDs, appeared. In 1986, Hayashi et al. observed a remarkable reduction of the driving voltage by inserting a polythiophene-electropolymerized thin film between an indium-tin-oxide (ITO) anode and a perylene-deposited film.30 The insertion of the polythiophene thin... 

The main impetus for the incorporation of porphyrins into conjugated polymers is to develop photosynthetic and enzyme mimics. Porphyrins were recently incorporated into rr-conjugated polymers (e.g., PPE, PPV), linear porphyrin tapes, and electropolymerized thin films. 

Nyokong T, Bedioui F (2006) Self-assembled monolayers and electropolymerized thin films of phthalocyanines as molecular materials for electroanalysis. J Porphyr Phthalocya 10 1101-1115... 

Nyokong T, Bedioui F (2006) Self assembled monolayers and electropolymerized thin films of phthalocyanines as molecular materials for electroanalysis. J Praph Phthal 10 1101-1115 Salomon E, Angot T, Papageorgiou N, Layet JM (2005) Self-assembled monolayer of tin-phthalocyanine on lnSb(0 0 l)-(4 x 2)/c(8 x 2). Surf Sci 596 74—81... 

The enzyme can be immobilized on the electrode by several techniques (53). The simplest method, first used in 1962, is to trap an enzyme solution between the electrode surface and a semipermeable membrane. Another technique is to immobilize the enzyme in a polymer gel such as polyacrylamide which is coated on the electrode surface. Very thin-membrane films can be obtained by electropolymerization techniques (49,54,55) using polypyrrole, polyindole, or polyphenylenediamine films, among others. These thin films (qv) offer the advantage of improved diffusion of substrate and product that... 

Electropolymerization is also an attractive method for the preparation of modified electrodes. In this case it is necessary that the forming film is conductive or permeable for supporting electrolyte and substrates. Film formation of nonelectroactive polymers can proceed until diffusion of electroactive species to the electrode surface becomes negligible. Thus, a variety of nonconducting thin films have been obtained by electrochemical oxidation of aromatic phenols and amines Some of these polymers have ligand properties and can be made electroactive by subsequent inincorporation of transition metal ions... 

Very thin films (ca. 10 nm) formed by electropolymerization can be used to effectively prevent signals due to interferences. Figure 1 shows a cyclic voltammogram for the electropolymerization of poly(l,3-DAB) onto a platinum ultramicroelectrode (25/un diameter). Note how the current decreases with each subsequent scan, indicating coverage of the electrode surface. 

Through the combination of SPR with a - poten-tiostat, SPR can be measured in-situ during an electrochemical experiment (electrochemical surface plasmon resonace, ESPR). Respective setups are nowadays commercially available. Voltammetric methods, coupled to SPR, are advantageously utilized for investigations of - conducting polymers, thin film formation under influence of electric fields or potential variation, as well as - electropolymerization, or for development of -> biosensors and - modified electrodes. Further in-situ techniques, successfully used with SPR, include electrochemical - impedance measurements and -+ electrochemical quartz crystal microbalance. 

The second section of this paper deals with the synthesis of new Ru and Os derivatives of 4-vinylpyridine (vpy) trans-4-stil-bazole (stilb) and trans-1,2-bis-(4-pyridyl)-ethylene (BPE) and their electroinitiated polymerization reactions. The electropolymerization (EP) reactions of the BPE and stilb complexes represent graphic examples of the broad scope of this surface derivatization technique that is available with substituted vinyl-pyridine ligands (6). These studies have provided considerable insight into structural and electronic influences on thin film formation. 

Electropolymerization of 4-Vinylpyridine Complexes. Investigations of Structural and Electronic Influences on Thin Film Formation. The recent discovery of the reductive polymerization of complexes containing vinylpyridyl ligands (lg), such as Ru -(bpy)2(vpy)22+ has led to the preparation of homogeneous thin layers of very stable electroactive polymers. This method has been extended to 4-vinyl-4 -methyl-2,2 -bipyridine (lg, 21a) and 4-vinyl-l,10-phenanthroline (21b) on both ruthenium and iron. In the following section we discuss our results on thin films derived from the polymerizable ligands BPE and the trans-4 -X-stilbazoles, (4 -X-stilb X - Cl, OMe, CN and H). 

Ultrasound was also used for the dispersion of a surfactant pyrrole, prior to electrooxidation to the conducting polymer [233]. An amphiphilic (pyrrolylalkyl) ammonium monomer dispersion was used to coat the electrode surface with monomer, subsequently electropolymerized to thin films using an aqueous electrolyte for this step. Ultrasound has also been used to assist impregnation of pyrrole monomer into, for example, a conventional polymer matrix prior to polymerization to yield a composite of the conducting and conventional polymers, but is also a pretreatment effect of ultrasound rather than a sonoelectrochemical one [234],... 

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