Polymerization electrolysis, controlled potential

Electrochemical reduction of phthaloyl dichloride (73) at a carbon or mercury cathode in acetonitrile containing TEAP led to a complex array of products. Six cathodic waves observed in the CV for the reduction of phthaloyl dichloride arise from the reductions of different electrolysis products, as well as from hydrolytically formed phthalic anhydride (74),. caused by the presence of residual water in the solvent/supporting electrolyte (equation 45). From controlled potential electrolyses of phthaloyl dichloride, a variety of products including 3-chlorophthalide (75), phthalide (76), biphthalyl (77) and dihydrobiph-thalide (78) can be obtained69,70. Reduction of glutaryl dichloride (79) at a mercury cathode in acetonitrile containing 0.1M TEAP results in the formation of 5-chlorovalerolactone (80) and valerolactone (81) as minor products, and a polymeric material (equation 46)68. 

Electrochemical polymerization of pyrrole on an SWNT electrode using an aqueous HCl 0.5 M solution as electrolyte, resulted in deposition of a PPy film onto the SWNT layer leading to a composite with a bilayer structure, as demonstrated by Raman spectroscopy [112]. Anew method was developed by S.Cosner eta/, in 2008 [111] SWNTs were functionalized by electropolymerizable pyrrole groups following covalent and noncova-lent strategies. The covalent pyrrole grafting was carried out by ester formation between pyrrole alcohol and chemically oxidized SWNTs. The strong Ti-interactions between pyrene and SWNTs were exploited for the noncovalent adsorption of a new pyrene-pyrrole derivative on the pristine CNT surface. The pyrrole-ester-SWNTs were solubilized in THE and electropolymerized by controlled potential electrolysis at 0.95 V. The PPy/SWNT... 

The anodic oxidation of alkanes in anhydrous hydrogen fluoride has been studied at various acidity levels from basic medium (KF) to acidic medium (SbFs) to establish optimum conditions for the formation of carbenium ions . The oxidation potential depends on the structure of the hydrocarbon methane is oxidized at 2.0 V, isopentane at 1.25 V vs Ag/Ag. Three cases of oxidation can be distinguished. In basic medium, direct oxidation of the alkane to its radical cation occurs. In a slightly acidic medium, the first-formed radical cation disproportionates to cation, proton and alkane. The oxidation is, however, complicated by simultaneous isomerization and condensation reactions of the alkane. In strongly acidic medium, protonation of the alkane and its dissociation into a carbenium ion and molecular hydrogen occurs. In acidic medium n-pentane behaves like a tertiary alkane, which is attributed to its isomerization to isopentane. The controlled potential electrolysis in basic medium yields polymeric species. 

All the adenosine complexes studied in this work have linear polymeric structures and N(l)-N(7) bonded adenosine and all but the Fe(II) complex contain coordinated water. Spectra obtained during reduction of the Cu-adenosine complex show some copper demetallation with some Cu(I) remaining complexed. A complication is that the mechanism of reduction may be dependent upon the way potential is applied, i.e., products of a single step controlled potential electrolysis at -1.75 V may be different than those obtained following step-by-step reductions prior to peak III. 

Polypyrrole and many of its derivatives can be synthesized via simple chemical or electrochemical methods [120]. Photochemically initiated and enzyme-catalyzed polymerization routes have also been described but less developed. Different synthesis routes produce polypyrrole with different forms chemical oxidations generally produce powders, while electrochemical synthesis leads to films deposited on the working electrode and enzymatic polymerization gives aqueous dispersions [Liu. Y. C, 2002, Tadros. T. H, 2005 and Wallace. G. G, 2003]. As mentioned above the electrochemical polymerization method is utilized extensively for production of electro active/conductive films. The film properties can be easily controlled by simply varying the electrolysis conditions such as electrode potential, current density, solvent, and electrolyte. It also enables control of thickness of the polymers. Electrochemical synthesis of polymers is a complex process and various factors such as the nature and concentration of monomer/electrolyte, cell conditions, the solvent, electrode, applied potential and temperature, pH affects the yield and the quality of the film... 

Electrochemical polymerization provides a convenient approach to fabricate CNTs/CP nanocomposites [46-53], Using such a strategy, the morphology and properties of the nanocomposites can be controlled by the electropolymerization conditions, such as the applied potential or current density. Ajayan and co-workers have reported the electrochemical oxidation of aniline in H SO on the CNTs electrode to fabricate CNT/PANl composites [46]. Chen et al. fabricated CNT/PPy nanocomposites, the first example of anionic CNTs acting as the dopant of a CP [47]. Their results showed that PPy was xmiformly coated on the surface of individual CNTs by electrolysis at a low apphed potential for a short time, rendering them potential applications in nanoelectronic devices. Another kind of CNTs/CP composite nanostructures, e.g., CNTs as inorganic fillers in CP matrices [54] can be prepared by a template-directed electropolymerization method. (Figure 13.3)... 

Fe cathodes during the electrolysis of diacetone acrylamide or acryh de solutions containing H2O2 claimed by literature as formed by electropdymerization had been more likely obtained by the catalysis of the Fe /H202 redox couple originated in situ from Fe corrosion. In this view the potential applied to the Fe dieet cathodes controlled only the metal dissolution in the acid medium to a low extent which did not cause any polymerization in the bulk. 

The results of electrocopolymerization and redox initiated copdymerization of methacrylic acid with A, iV -methylenebisaciylamide are presented in Fig. The selection of these two monomers for the present study was based upon the fact that these monomers do not undergo significant side reactions, other than the main vinyl polymerization reaction, during electrolysis of their aqueous solutions l Of these two monomers, only methacrylic acid ionizes in aqueous solutions. It was, therefore, anticipated that the methacrylic acid ion will experience a coulombic repulsicm from the aluminium cathode which will affect its incorporation in the copdymer forming on the cathode. Further, by controlling the degree of ionization of methacrylic add and the potential of aluminium cathode, an electrolytic control of the copdymer composition mi t become possil. ... 

It is a new procedure for continuously controlling the ratio of activator to deactivator by electrochemical procedures. Electrochemical methods offer multiple readily adjustable parameters, for example, applied cunent, potential, and total charge passed, to manipulate polymerization rates by selective targeting of the desired concentration of the redox-active catalytic sf>ecies. As discussed below, tydic voltammetric (CV) studies of copper complexes suitable for catalyzing ATRP have been used for over a decade to measure the activity of copper-based catalyst complexes in an ATRP. In the CV studies it was found that the fil/2 value for the redox couple Cu /Cu strongly depends on the nature of the ligand and the halogen. However, application of a continuous electrochemical stimulus (i.e., electrolysis), which can be uniquely paired... 

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