TY - GEN A1 - Lange, Ulrich A1 - Mirsky, Vladimir M. T1 - Electroanalytical measurements without electrolytes: Conducting polymers as probes for redox titration in non-conductive organic media T2 - Analytica Chimica Acta N2 - Electroanalytical methods have been applied only in conducting media. An application of conducting polymers allows to overcome this limitation. If such material is in electrochemical equilibrium with dissolved redox active species, its electrical conductivity depends on the redox potential of these species. Therefore, conductometric measurements with conducting polymers can provide about the same information as classical redox electrodes. The approach was applied for redox titration. Equivalent points obtained by this titration in aqueous and organic electrolytes were identical. Then the approach was applied for determination of bromine number by redox titration in non-conducting organic phase. KW - Conducting polymers KW - Redox titration KW - Conductometric sensors KW - Non-conductive media Y1 - 2012 U6 - https://doi.org/10.1016/j.aca.2012.07.024 SN - 0003-2670 VL - 744 SP - 29 EP - 32 ER - TY - GEN A1 - Lange, Ulrich A1 - Mirsky, Vladimir M. T1 - Polythiophene films on gold electrodes: A comparison of bulk and contact resistances in aqueous and organic media T2 - Journal of Solid State Electrochemistry N2 - Recently, developed technique for separated analysis of bulk and contact resistance was applied for the investigation of polythiophene films electropolymerized in boron trifluoride diethylether. Kinetics of polymer resistance and for the first time of the contact resistance during polymer oxidation and reduction were characterized. Influence of electrochemically controlled oxidation state on the polymer bulk and the polymer/metal contact resistance was measured in aqueous and organic environment. Variation of the electrical potential from −0.2 to 1.1 V vs. Ag/AgCl (sat) leads to an increase of the polymer conductivity for about three orders of magnitude and to a decrease of the contact resistance for about three orders of magnitude. The potential dependence of the two resistances was different, especially at high anodic potentials. In organic solution, the change of both resistances was more than six orders of magnitude. The results were compared with electrochemical and spectroelectrochemical data, a difference in the material behavior depending on the electrolyte solvent was observed. The influence of electrical potential on polymer resistance in aqueous solution was explained quantitatively by a three-state model with the values of oxidation potential +0.3 and +1.2 V. KW - Polythiophene KW - In situ conductivity measurement KW - s24-Technique KW - Spectroelectrochemistry KW - Conducting polymers Y1 - 2011 U6 - https://doi.org/10.1007/s10008-011-1450-4 SN - 1433-0768 VL - 15 IS - 11 SP - 2377 EP - 2382 ER - TY - GEN A1 - Ivanov, Svetlozar D. A1 - Lange, Ulrich A1 - Tsakova, Vessela T. A1 - Mirsky, Vladimir M. T1 - Electrocatalytically active nanocomposite from palladium nanoparticles and polyaniline: Oxidation of hydrazine T2 - Sensors and Actuators B: Chemical N2 - The layer by layer (LbL) adsorption technique was used to deposit a new electrocatalytic material consisting of palladium nanoparticles (Pd NPs) and polyaniline (PANI). As far as PANI adsorption did not affect the reactivity of the Pd NPs attached in the former adsorption step, the LbL technique offered the way of increasing the reactive Pd surface within a three-dimensional nanocomposite structure. In situ conductance measurements have shown that depending on the concentration of the PANI solution, used for the LbL adsorption, composites with either PANI-like (dependent on potential and pH) or metal-like (non-dependent on potential and pH) conductive behaviour can be obtained. Metal-like Pd NPs–PANI nanocomposites were studied as electrocatalytic materials for hydrazine oxidation. A linear concentration dependence of the voltammetric peak currents was observed in the 40–800 μM hydrazine concentration range, the sensitivity increasing with the amount of adsorbed Pd NPs. Amperometric measurements showed linear response in the 10–300 μM range with sensitivity 0.5 μA/μmol cm−2 and a theoretical detection limit estimated to be 0.06 μM. KW - Conducting polymers KW - Pd-nanoparticles KW - LbL adsorption KW - Hydrazine Y1 - 2010 U6 - https://doi.org/10.1016/j.snb.2010.07.004 SN - 0925-4005 VL - 150 IS - 1 SP - 271 EP - 278 ER - TY - GEN A1 - Lange, Ulrich A1 - Roznyatovskaya, Nataliya V. A1 - Mirsky, Vladimir M. T1 - Conducting polymers in chemical sensors and arrays (invited review) T2 - Analytica Chimica Acta N2 - The review covers main applications of conducting polymers in chemical sensors and biosensors. The first part is focused on intrinsic and induced receptor properties of conducting polymers, such as pH sensitivity, sensitivity to inorganic ions and organic molecules as well as sensitivity to gases. Induced receptor properties can be also formed by molecularly imprinted polymerization or by immobilization of biological receptors. Immobilization strategies are reviewed in the second part. The third part is focused on applications of conducting polymers as transducers and includes usual optical (fluorescence, SPR, etc.) and electrical (conductometric, amperometric, potentiometric, etc.) transducing techniques as well as organic chemosensitive semiconductor devices. An assembly of stable sensing structures requires strong binding of conducting polymers to solid supports. These aspects are discussed in the next part. Finally, an application of combinatorial synthesis and high-throughput analysis to the development and optimization of sensing materials is described. KW - Conducting polymers KW - Chemical sensors KW - Electroactive polymers KW - Gas sensors KW - Combinatorial techniques KW - Electropolymerization KW - Sensor array Y1 - 2008 U6 - https://doi.org/10.1016/j.aca.2008.02.068 SN - 0003-2670 VL - 614 IS - 1 SP - 1 EP - 26 ER -