Redox Copolymerization Research Articles

An oxygen cathode operating in a physiological solution.

We report the electroreduction of O(2) to water under physiological conditions (pH 7.4, 0.15 M NaCl, 37.5 degrees C) at a current density of 5 mA cm(-2) and at a potential only 0.18 V reducing versus that of the reversible O(2)/H(2)O electrode at pH 7.4. The immobilized electrocatalyst enabling the reduction is the electrostatic adduct of bilirubin oxidase from Myrothecium verrucaria, a polyanion at pH >4.1, and the polycationic redox copolymer of polyacrylamide and poly (N-vinylimidazole) complexed with [Os (4,4'-dichloro-2,2'-bipyridine)(2)Cl](+/2+), cross-linked on carbon cloth. The current density of the rotating electrodes was O(2) transport limited up to 8.8 mA cm(-2); their kinetic limit was reached at 9.1 mA cm(-2). The operational life of the electrodes depended on their angular velocity, which defined not only the current density but also the mechanical shear stress stripping the electrocatalyst. When the electrodes were rotated at 300 rpm and were poised at -256 mV versus the potential of the reversible O(2)/H(2)O electrode, their 2.4 mA cm(-2) initial current density decreased to 1.3 mA cm(-2) after 6 days of continuous operation at 37.5 degrees C.

Thermoresponsive poly( N-isopropylacrylamide- co-acrylamide- co-2-hydroxyethyl methacrylate) hydrogels

In this study, hydrogels having a thermoresponsive character were prepared from the ternary systems N-isopropylacrylamide/acrylamide/2-hydroxyethyl methacrylate by a redox copolymerization method. Hydrogels with different thermoresponsive properties were obtained by changing the initial NIPAM/AAm and NIPAM/HEMA mole ratios and total monomer concentration.

A macromolecular N, N-dichlorosulfonamide as oxidant for residual sulfides

A redox copolymer, a macroporous poly(S/DVB) resin bearing N, N-dichlorosulfonamide groups, was used to remove residual sulfides from aqueous solutions by its oxidation to non-toxic products. The resin contains 8.2 meq active chlorine/g and shows strong oxidizing properties. It was employed in static and flow processes for treatment of sulfide solutions containing 32, 100 or 320 mg S 2−/dm 3. The effects of various parameters on the reaction course have been studied (molar ratio of the reagents, alkalinity of the reaction media, flow rate in column processes). The data showed that the reactive copolymer easily oxidizes sulfides––it was possible to reduce the concentration below 10 μg S 2−/dm 3. During oxidation processes the formation of two end products was confirmed––these were sulfates (in majority) and sulfur which causes the turbidity of the effluents. The reaction conditions to eliminate sulfur formation were sought. To utilize the polymer-bonded active chlorine with good efficiency, it was necessary to maintain a suitable level of alkalinity of the influx. The exhausted copolymer contained unsubstituted sulfonamide groups. It could be regenerated with a slightly acidified sodium chlorate(I) and reused for further processes.

Synthesis of thermoresponsive N-isopropylacrylamide–N-hydroxymethyl acrylamide hydrogels by redox polymerization

In this study, a random copolymer of N-isopropylacrylamide and N-hydroxymethyl acrylamide [poly(NIPAM-co-NHMAAm)], having a thermoresponsive character was prepared by a redox copolymerization method. Poly(ethylene glycol), PEG 4000, was used to increase the thermoresponsitivity of the resultant copolymeric structures. NIPAM-co-NHMAAm copolymers with different thermoresponsive properties were obtained by changing the initial NIPAM/NHMAAm mole ratio, total monomer, PEG 4000, and N,N′-methylenebisacrylamide, (MBAAm), concentrations.

A macromolecular N, N-dichlorosulfonamide as oxidant for thiocyanates

Macroporous S/DVB copolymer containing N, N-dichlorosulfonamide groups was used for removal of thiocyanate ions from aqueous solutions. This copolymer contains active chlorine in functional groups (8.2 meq Cl ∗/g) and oxidises thiocyanates to considerably less toxic products (such as sulphate, cyanate, carbonate and ammonium ions). The resin was employed in static and dynamic conditions and thiocyanate solutions containing 116 or 560 ppm SCN − were treated. The effects of various parameters on the rates of reaction have been studied. The proposed method is particularly advantageous for treating highly diluted solutions. Using this redox copolymer, it was possible to reduce thiocyanate concentration in solutions below 0.5 mg SCN −/dm 3. The oxidation capacity of the resin was found to be nearly 60 mg SCN −/g. The resin was especially efficient for removal of SCN − ions from neutral and weakly acidic solutions, whereas in alkaline media it lost a part of its oxidising properties as a result of escape of active chlorine. Reactivation of the stripped resin was performed in a one-step treatment by an acidified solution of sodium chlorate(I). The regenerated copolymer can be reused in the next cycle.

Dispersion redox copolymerization of methyl methacrylate with macromonomeric azoinitiator as a macrocrosslinker

The dispersion copolymerization of methyl methacrylate (MMA) with macromonomeric azoinitiator, MIM-400, as a macrocrosslinker initiated by the benzoyl peroxide (BPO)/N,N′dimethylaniline (DMA) coupled in water/ethanol (4/1, v/v) at 20°C was carried out to yield PEG-b-PMMA networks with labile azo linkages in the main chain. Gel fraction, swelling ratios (qv) and the average molecular weights between junction points (Mc) values of the networks were investigated. Maximum gel fraction was obtained using 0.133M MIM-400, 9.2×10−2M BPO, 2.1×10−2M DMA and 2.19M MMA.

A macromolecular N, N-dichlorosulfonamide as oxidant for cyanides

The possibility of the use of a redox copolymer—a macroporous poly(styrene-co-divinylbenzene) resin having N, N-dichlorosulfonamide groups—as macromolecular oxidant for destruction of cyanide ions contained in dilute aqueous solutions has been investigated in this report. The resin contains two atoms of active chlorine in functional groups and shows strong oxidising properties. It was employed in static and flow systems for transformation of cyanide ions to non-toxic compounds. The reactions were carried out in aqueous media containing 26–2600 mg CN −/dm 3 at pH in the range 10–14. The data showed that the macromolecular oxidant easily decomposes cyanides forming cyanates which are unstable in aqueous solutions—they hydrolyse to carbonates and ammonia. Both of the two atoms of active chlorine attached to the sulfonamide group of the reactive copolymer show oxidising properties in relation to cyanide ions but their activity is different in examined conditions. In strong alkaline medium one of these atoms easily quits the resin phase and instantly oxidises cyanides, whereas the second of them bound more strongly oxidises cyanide in static condition in a longer time. To utilise with good efficiency both of the two atoms of active chlorine for destruction of cyanide ions in processes carried out in flow systems it is necessary to maintain the level of basicity of the influent as low as possible.

Electron Transfer Reaction from Glucose Oxidase to an Electrode via Redox Copolymers

This study has aimed at exploring the relationship between redox polymer structures and the electron transfer reaction from glucose oxidase (GOx) to an electrode via the redox polymers. Two series of flexible redox copolymers; poly[vinylferrocene-co-α-methacryloyl-ω-methoxy-oligo(ethylene oxide)] (VFc-MEO) and poly(vinylferrocene-co-dodecyl methacrylate) (VFc-MD), were prepared, where VFc and MD are hydrophobic monomers, while MEO is a hydrophilic monomer. These redox copolymers were utilized as electron mediators for the enzymatic reaction of GOx in carbon paste electrodes. Both of the flexible VFc-MEO and VFc-MD copolymers were found to function as polymeric mediators for the electron transfer reaction between GOx and the electrode, while the catalytic current responses were completely different depending on the structure of the polymeric mediators. The magnitude of the catalytic current of the VFc-MEO electrodes was larger than that of the VFc-MD electrodes at any VFc composition in the copolymers. At a constant glucose concentration, the catalytic current of the VFc-MEO electrodes passed through a maximum with increasing the VFc composition in the copolymers, whereas that of the VFc-MD electrodes monotonously increased with increasing the VFc composition. These differences in the electron transfer reaction have been explained in terms of the difference in amphiphilicity of the copolymers.

A redox copolymer containing active bromine as oxidant for thiocyanates

A polymeric oxidizing agent was used for removal of thiocyanate ions present in low concentration aqueous solutions. This redox polymer was a macroporous S/DVB copolymer with N-bromosulfonamide groups which contained 3.30 meq g–1 active bromine. It was prepared by chemical modification of Amberlyst 15. The resin was employed in static and dynamic conditions to oxidize thiocyanate ions to less toxic products, such as sulfate, carbonate and ammonium ions. The effects of various parameters on the course of the reaction have been studied. The resin was specially efficient for removal of SCN– ions from neutral and alkaline solutions (final thiocyanate concentrations dropped below 0.5 mg L–1) whereas in acidic solutions (at pH < 2) the resin lost its oxidizing properties as a result of the active bromine escaping. The functional groups of the reactive polymer during thiocyanate treatment undergo debromination to give sulfonamide groups. The regeneration of the stripped resin can readily be achieved practically without losing its initial reactivity after a few cycles. Thiocyanat-Ionen wurden mit Hilfe eines polymeren Oxidationsreagens' aus verdünnten wäßrigen Lösungen entfernt. Das Redoxpolymere war ein makroporöses S/DVB-Copolymer mit N-Bromsulfonamid-Gruppen, welches 3,30 meq g–1 aktives Brom enthielt. Es wurde aus Amberlyst 15 synthetisiert. Das Harz wurde sowohl unter statischen als auch dynamischen Bedingungen angewandt, um Thiocyanate zu weniger toxischen Produkten wie Sulfaten, Carbonaten und Ammonium-Ionen zu oxidieren. Der Einfluß von verschiedenen Parametern auf den Reaktionsverlauf wurde untersucht. Das Harz war besonders effizient bei der Thiocyanat-Entfernung aus neutralen und basischen Lösungen (wobei die Thiocyanat-Konzentration unter 0,5 mg L–1 sank), dagegen verlor das Harz in sauren Lösungen (bei pH < 2) durch Freisetzung von Brom seine Oxidationseigenschaften. Während der Thiocyanat-Behandlung unterliegen die funktionellen Gruppen des reaktiven Polymeren einer Debromierung zu Sulfonamidgruppen. Die Regeneration des verbrauchten Harzes kann über mehrere Zyklen ohne nennenswerten Verlust der Anfangsreaktivität durchgeführt werden.

A macromolecular N-chlorosulfonamide as oxidant for thiocyanates

A redox copolymer, macroporous poly(S/DVB) resin having N-chlorosulfonamide groups – obtained by chemical modification of Amberlyst 15 – was used for removal of thiocyanates from aqueous solutions. This resin contains active chlorine in functional groups (2.15 mmol/g) and shows oxidative properties. It was employed in static and flow systems to oxidise thiocyanate ions to less toxic compounds. The reactions were carried out in aqueous media containing 116 or 580 mg SCN −/dm 3 at different pH values. The data showed that the –SO 2NClNa groups containing resin easily oxidised thiocyanates forming sulphates and cyanates. Cyanates are unstable under the reaction conditions (hydrolysis). The concentration of thiocyanates dropped below 0.5 mg/dm 3 in most of the tested solutions. The thiocyanate-oxidising capacity of the resin was found to be 0.55 mmol/g. The kinetic course of the reaction strongly depends on the pH of the reaction medium (acidic medium>neutral medium>alkaline medium). The functional groups of the reactive copolymer during thiocyanate treatment undergo dechlorination to sulfonamide groups. The exhausted copolymer can be regenerated by sodium chlorate(I) and reused for continuous processes.

Electrogeneration of Biotinylated Functionalized Polypyrroles for the Simple Immobilization of Enzymes

A new biotin derivative functionalized by a pyrrole group has been synthesized. This functionalization has allowed the preparation of the first example of a poly(pyrrole-biotin) film by oxidative polymerization. In addition, the successful copolymerization of a polypyridinyl complex of ruthenium(II) containing pyrrole groups with the biotin derivative provided redox copolymers exhibiting specific adsorption sites. The resulting copolymer electrodes were applied to the immobilization of a biotinylated glucose oxidase through an avidin bridge. An avidin-conjugated alkaline phosphatase was also immobilized by direct specific adsorption onto the biotinylated polymer. The amperometric response of the resulting biosensors to glucose and phenylphosphate has been studied.

Characterization of poly(vinylferrocene- co-2-hydroxyethyl methacrylate) for use as electron mediator in enzymatic glucose sensor

A series of novel copolymers, poly(vinylferrocene-co-2-hydroxyethyl methacrylate) (VFc-HEMA), has been prepared by radical copolymerization and characterized. These copolymers have been utilized as polymeric mediators for amperometric glucose sensors. Glucose oxidase (GOx) and the redox copolymers were mixed with carbon paste, and carbon-paste enzyme electrodes were prepared to amperometrically detect concentrations of glucose. From cyclic voltammetry measurements using the enzyme electrodes in the absence and presence of glucose, these copolymers were proved to function as polymeric mediators between the redox center of GOx and the electrode. The composition of VFc-HEMA incorporated in the enzyme electrodes influenced the current response.

Preparation and characterization of thermoresponsive isopropylacrylamide-hydroxyethylmethacrylate copolymer gels

A random copolymer of N-isopropylacrylamide and 2-hydroxyethylmeth-acrylate, poly(NIPAM-co-HEMA), having thermoresponsive character was prepared bya redox copolymerization method. Poly(ethylene glycol), PEG 4000 was included in the copolymerization recipe to increase the thermoresponsivity of copolymeric structure. Poly(NIPAM-co-HEMA) copolymer gels having more elastic character and higher mechanical strength relative to poly(NIPAM) gel could be achieved by the proposed copolymerization procedure. The equilibrium and dynamic response against the temperature were investigated for the gel matrices produced by changing the initial NIPAM/HEMA mol ratio and PEG 4000 concentration in the copolymerization mixture. The effective diffusion coefficient of water within the gel matrix was estimated for either swollen or shrunken states by applying an unsteady-state diffusion model on the dynamic swelling and shrinking behaviors of gel matrix prepared in the cylindrical form. © 1998 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 36: 527–541, 1998

Redox copolymer with N‐bromosulfonamide groups for the decomposition of cyanide ions in dilute aqueous solutions

AbstractA redox copolymer, macroporous poly(styrene‐co‐divinylbenzene) (S/DVB) resin having N‐bromosulfonamide groups, was used for removal of cyanide ions from aqueous solutions. This resin contains active bromine in functional groups (1.86 mmol g−1, i. e. 3.72 meq g−1) and shows oxidative properties. It was employed in static and flow system for oxidation of cyanide ions to non‐toxic compounds. The reactions were carried out in aqueous media containing 26–2600 mg L−1 CN− at different pH values. The data showed that the resin having active bromine easily oxidized cyanides, forming cyanates being 1000‐times less toxic than cyanides. In contact with the resin the concentration of cyanides in tested solutions dropped below 0.05 mg L−1 CN−. During the oxidation processes the SO2NBrNa groups transform to SO2NH2 groups. They can be reactivated by use of sodium hypochlorite and bromide solutions. As an alternative to oxidation of cyanides by N‐bromosulfonamide resin, the oxidation of these ions by N‐chlorosulfonamide resin with addition of a small amount of bromides was examined.

A redox copolymer having N-chlorosulfonamide groups for cyanide ion decomposition in dilute aqueous solutions

A redox copolymer, macroporous poly(S/DVB) resin having N-chlorosulfonamide groups was used for removal of cyanide ions from aqueous solutions. This resin contains active chlorine in functional groups (2.3 mmoUg, i.e., 4.6 meq/g) and shows oxidative properties. The possibility of using this resin for oxidation of cyanide ions to less toxic or non-toxic compounds was investigated in aqueous media containing different amounts of these ions (26–2600 mg CN −/dm 3) and at different pH values. Examples of the use of the macromolecular chloramine as a polymer supported reagent for oxidation of cyanides in static and dynamic conditions are given. The data showed that the oxidative properties of the N-chlorosulfonamide resin in contact with cyanide ions are remarkable. Active chlorine easily oxidized cyanides forming cyanates (1000-times less toxic than cyanides). In contact with the resin the concentration of cyanides in the majority of tested solutions dropped below 0.05 mg CN −/dm 3. During oxidation processes the -S0 2NCINa groups transform to −SO 2NH 2 groups. They can be regenerated by the use of hypochlorite solutions.

Preparation of Novel Redox Copolymers : Poly [ferrocenylmethyl methacrylate-co-methoxy-oligo (ethylene oxide) methacrylate], and Their Use as Polymeric Mediators in Amperometric Glucose Sensors

Preparation of Novel Redox Copolymers : Poly [ferrocenylmethyl methacrylate-co-methoxy-oligo (ethylene oxide) methacrylate], and Their Use as Polymeric Mediators in Amperometric Glucose Sensors

Electron-Transfer Communication in Glutathione Reductase Assemblies: Electrocatalytic, Photocatalytic, and Catalytic Systems for the Reduction of Oxidized Glutathione

Glutathione reductase, GR, is electrically communicated with its environment in electrochemical, photochemical, and chemical assemblies. Electron-transfer communication between the protein redox site and its surroundings is achieved either by covalent attachment of electron relays to the protein or by using redox copolymers as electron mediators. GR is covalently attached to self-assembled monolayers of the N-hydroxysuccinimide ester of cysteic acid formed by chemisorption of the respective disulfide, 1, onto Au electrodes. The resulting GR monolayer electrode is derivatized by N-methyl-N'(carboxyalkyl)-4,4'-bipyridinium (2) in the presence of urea

Synthesis and characterization of redox copolymers of tris(4-vinyl-4'-methyl-2,2'-bipyridine)ruthenium(2+) and tris(4-vinyl-4'-methyl-2,2'-bipyridine)osmium(2+): unusual energy-transfer dynamics

ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTSynthesis and characterization of redox copolymers of tris(4-vinyl-4'-methyl-2,2'-bipyridine)ruthenium(2+) and tris(4-vinyl-4'-methyl-2,2'-bipyridine)osmium(2+): unusual energy-transfer dynamicsS. L. Bommarito, S. P. Lowery-Bretz, and H. D. AbrunaCite this: Inorg. Chem. 1992, 31, 3, 502–507Publication Date (Print):February 1, 1992Publication History Published online1 May 2002Published inissue 1 February 1992https://doi.org/10.1021/ic00029a030RIGHTS & PERMISSIONSArticle Views83Altmetric-Citations17LEARN ABOUT THESE METRICSArticle Views are the COUNTER-compliant sum of full text article downloads since November 2008 (both PDF and HTML) across all institutions and individuals. These metrics are regularly updated to reflect usage leading up to the last few days.Citations are the number of other articles citing this article, calculated by Crossref and updated daily. Find more information about Crossref citation counts.The Altmetric Attention Score is a quantitative measure of the attention that a research article has received online. Clicking on the donut icon will load a page at altmetric.com with additional details about the score and the social media presence for the given article. Find more information on the Altmetric Attention Score and how the score is calculated. Share Add toView InAdd Full Text with ReferenceAdd Description ExportRISCitationCitation and abstractCitation and referencesMore Options Share onFacebookTwitterWechatLinked InReddit PDF (746 KB) Get e-Alerts Get e-Alerts

Reactivity Ratios in the Redox Copolymerization of Methacrylamide and Methyl Methacrylate in Dimethylformamide

Reactivity Ratios in the Redox Copolymerization of Methacrylamide and Methyl Methacrylate in Dimethylformamide

Reactivity Ratios in the Redox Copolymerization of Acrylamide and n-Butyl Acrylate in Dimethylformamide

Abstract Copolymerization of acrylamide and n-butyl acrylate in DMF initiated by the redox system CNCH2COOH/Mn(OAc)3 has been investigated in the temperature range 20 to 35°C. The data on reactivity ratios are compared with those of other monomer pairs involving acrylamide, and the values obtained using benzoyl peroxide as the initiator are presented.