Electrodeposition of polypyrrole–Au nanoparticles composite from one solution containing gold salt and monomer

An easy method of preparation of polymer/metal–nanoparticle composites is reported. KAu(CN)₂ and pyrrole do not react (redox reaction) in solutions of moderate pH. The gold complex, due to its inertness, is stable in the presence of 10 μM CN^? for weeks. Therefore the electrodeposition of controlled amounts of polypyrrole and Au nanoparticles on the graphite surface can be done in one solution by applying a sequence of 0.75 and ? 1.6 V potentials. Pulse deposition of both components leads to substantial improvement of the layer smoothness and homogenous distribution of Au nanocrystallites.     

Electrodeposition of poly(N-vinylcarbazole) at the three-phase junction. Formation of very different polymer structures

Poly(N-vinylcarbazole) films can be deposited at the three-phase boundary when the organic phase contains only monomer, N-vinylcarbazole, while the aqueous phase contains supporting electrolyte. A cylindrical platinum microelectrode is immersed into the two-liquid system in such a way that a part of it is located in one liquid and the other part resides in the second liquid. The thickness of the reaction layer, or the width of the microelectrode zone where the polymer grows, depends on the kind of ions present in the aqueous phase and the time of the experiment. The structure of the deposited polymer may be very different and depends on the distance from the three-phase boundary and the type of the anion present in the aqueous phase. The key parameters here are the local electrode potential and the local concentration of the anions. The list of obtained polymer structures includes, among others, arrays of perfectly arranged deep oval channels and groups of microcrystals. The porosity of the polymer deposits increases with the distance from the aqueous phase.     

Electrooxidation of undiluted organic liquids swelling<Emphasis Type="Italic"> N</Emphasis>-isopropylacrylamide-based copolymers

Polyacrylate gels such as: N-isopropylacrylamide (NIPA), ionic copolymer NIPA-co-sodium acrylate (NIPA-co-SA) and ionic copolymer NIPA-co-[2-(acryloyloxy)ethyl]trimethylammonium chloride (NIPA-co-XCl) were swollen by methanol, ethanol and N,N-dimethylformamide. These solvents were oxidized voltammetrically in the gels at platinum microelectrodes. The blocking coefficients, defined as the ratio of the currents observed in the presence and absence of the polymeric chains, were different for the solvents in the charged and uncharged polymers and did not differ for the electroactive probe, ferrocene, present in the solvents at millimolar level. This may mean that the micro ionic layer that is formed at microelectrodes at the plateau of the voltammetric solvent waves leads to a kind of collapse/phase transition of the polymer in the depletion layer. For methanol, the gel structure was found to prevent occasionally the formation of large gas bubbles at the potentials positive versus the first wave and then three one-electron waves could be obtained. Experiments done with a capillary cell and an optical microscope indicated that before formation of large bubbles at the Pt microelectrode a very dynamic, dense stream of microbubbles leaves the electrode surface.Dedicated to Zbigniew Galus on the occasion of his 70th birthday     

Theory of cyclic voltammetry at the mercury film electrode: Reversible case with substrate initially present in the mercury phase

The theory of cyclic voltammetry has been developed for a case describing the behaviour of a reversible system at the mercury film electrode with a metal present initially in the mercury phase. Theoretical results are presented in the form of a simple equation coupled with a set of the calculated current function values. In addition, several simple relationships are given for the parameters characterizing the cyclic curves. The rapid exhaustion of the metal from the mercury film and the generation of the metal ions into the solution free of metal ions offer better conditions for the resolution of adjacent peaks than those existing in cyclic voltammetry at the HMDE and at the MFE with substrate present initially in solution. Theoretical predictions were compared with experimental results obtained for lead and thallium at the silver-based mercury film electrode.