Atom transfer radical polymerization is a versatile technique for exerting precise control over polymer molecular weights, weight distributions, and complex architectures. Here, we show that an externally applied electrochemical potential can reversibly activate the copper catalyst this process by one-electron reduction of initially added air-stable cupric species (Cu(II)/Ligand). Modulation kinetics thereby tunable in real time varying magnitude potential. Application multistep intermittent...

The absolute potential of the standard hydrogen electrode, SHE, was calculated on basis a thermodynamic cycle involving H2(g) atomization, ionization H(g)• to H(g)+, and hydration H+. most up-to-date literature values free energies these reactions have been selected and, when necessary, adjusted electron convention Fermi−Dirac statistics since both e− H+ are fermions. As reference state for electron, we chosen at 0 K, which is one used in computational chemistry. Unlike almost all previous...

Photoinduced metal-free atom transfer radical polymerization (ATRP) of methyl methacrylate was investigated using several phenothiazine derivatives and other related compounds as photoredox catalysts. The experiments show that all selected catalysts can be involved in the activation step, but not them participated efficiently deactivation step. redox properties stability cations derived from were evaluated by cyclic voltammetry. Laser flash photolysis (LFP) used to determine lifetime...

Reversible-deactivation radical polymerization (RDRP) in the presence of Cu0 is a versatile technique that can be used to create well-controlled polymers with complex architectures. Despite facile nature technique, there has been vigorous debate literature as mechanism reaction. One proposed mechanism, named supplemental activator and reducing agent atom transfer (SARA ATRP), CuI major alkyl halides, acting activator, an inner-sphere electron occurring during activation step, relatively slow...

A debate has proceeded in the literature regarding mechanism of reversible-deactivation radical polymerization presence Cu0. The two proposed models are supplemental activator and reducing agent atom transfer (SARA ATRP) single electron living (SET-LRP). In SARA ATRP, CuI is major alkyl halides, Cu0 a excess CuII through comproportionation, disproportionation negligible. contrast, SET-LRP, activator, does not activate halides but instead undergoes instantaneous disproportionation. this...

High-level ab initio molecular orbital calculations are used to study the thermodynamics and electrochemistry relevant mechanism of atom transfer radical polymerization (ATRP). Homolytic bond dissociation energies (BDEs) standard reduction potentials (SRPs) reported for a series alkyl halides (R-X; R = CH 2CN, CH(CH 3)CN, C(CH 3) 2COOC 2H 5, 3)COOCH 3, 2COOCH 2Ph, 3)Ph, 3)Cl, 3)OCOCH CH(Ph)COOCH SO Ph; X Cl, Br, I) both in gas phase two common organic solvents, acetonitrile...

Polymerizations and mechanistic studies have been performed to understand the kinetic pathways for polymerization of monomer oligo(ethylene oxide) monomethyl ether acrylate (OEOA) in aqueous media. Typically, medium consisted 18 wt % OEOA water, presence Cu catalysts coordinated by tris[2-(dimethylamino)ethyl]amine (Me6TREN). Well-controlled can be achieved halide anions wire with ≲600 ppm soluble CuII species, rather than previously reported ca. 10 000 Cu0 particles formed...

Conducting an atom transfer radical polymerization (ATRP) in water provides several intriguing challenges. In order to attain a deeper understanding of the mechanism aqueous ATRP, with particular attention reasons for potential loss control, systematic investigation was carried out three copper-amine catalysts ([CuIIL]2+, L = PMDETA, TPMA and Me6TREN). The association constants (KX) [CuIIL]2+ [CuIL]+ X– OH–, as well relative stabilities redox properties complexes, were determined function...

A thermodynamic scheme representing the atom transfer radical polymerization (ATRP) equilibrium as formal sum of equilibria involving carbon−halogen bond homolysis and three additional distinct contributions related to catalyst is rigorously evaluated. The reduction/oxidation both metal complex halogen atom, affinity higher oxidation state for halide anions (or "halidophilicity"), are measured. validity self-consistency model verified by independently measuring, computing, or calculating...

Standard reduction potentials, SRPs, of the halogen atoms have been calculated in water on basis an appropriate thermochemical cycle. Using best up-to-date thermodynamic data available literature, we E(o)(X•/X-) values 3.66, 2.59, 2.04, and 1.37 V vs SHE for F•, Cl•, Br•, I•, respectively. Additionally, computed SRPs I• acetonitrile (CH3CN) dimethylformamide (DMF) by correcting obtained free energies transfer X• X- from to nonaqueous solvent S intersolvent potential between S. From E(o)(X...

Enhanced control: Electrochemically mediated atom transfer radical polymerization (ATRP) allows easy modulation of the overall rate and control through variation an external applied potential, Eapp (see picture). This method has been successfully to aqueous ATRP oligo(ethylene glycol) methyl ether methacrylate (OEOMA475) catalyzed by Cu/tris(2-pyridylmethyl)amine.

Direct electrolysis of CO2 in DMF at an inert electrode, such as mercury, produces mixtures CO and oxalate, whereas catalysed by radical anions aromatic esters nitriles exclusively oxalate the same medium. Examination previous results concerning direct electrochemical reduction photoinjected electrons reveals that there are no significant specific interactions between reactant, intermediates products on one hand, electrode material other, when this is Hg or Pb. These observations a...

Singly and multiply doped graphene oxide quantum dots have been synthesized by a simple electrochemical method using water as solvent. The obtained materials characterized photoemission spectroscopy scanning tunneling microscopy, in order to get detailed picture of their chemical structural properties. activity toward the oxygen reduction reaction has investigated cyclic voltammetry rotating disk electrode measurements, showing clear decrease overpotential function dopant according sequence:...

Mesoporous carbons are highly porous materials, which show large surface area, chemical inertness and electrochemical performances superior to traditional carbon material. In this study, we report the preparation of nitrogen-doped undoped mesoporous by an optimized hard template procedure employing silica as template, sucrose ammonia nitrogen source, respectively. Surface area measurements assert a value 900 600 m(2) g(-1) for best doped samples, Such supports were then thoroughly...

Electrochemically mediated atom transfer radical polymerization (eATRP) of n-butyl acrylate was systematically investigated using diminished catalyst concentrations (≤300 parts per million) under a variety formulations and electrochemical conditions. Critical parameters, including the applied potential, concentration, ligand, were explored correlated with rates, polymer properties, currents during eATRP process. Additional methods to improve feasibility galvanostatic Copper electrodeposition...

Abstract Simplification of electrochemically mediated atom transfer radical polymerization was achieved efficiently under either potentiostatic or galvanostatic conditions using an aluminum wire sacrificial anode ( se ATRP) immersed directly into the reaction flask without separating counter electrode. ATRP polymerizations were carried out different applied potentials, E app s= 1/2 , pc −40 mV, and −80 mV. As rate R p ) can be modulated by applying more reducing resulted in faster . The...

The reductive cleavage of a series organic chlorides, including chloroaromatics, benzyl activated chloroalkanes and polychloromethanes, was investigated at Ag, Cu, Pd glassy carbon (GC) electrodes in CH3CN + 0.1 M (C2H5)4NClO4. silver cathode either 2-mm diameter disc, fabricated from Ag wire, or nanoclusters average d = 304 nm, prepared by electrodeposition on GC. Cu have shown remarkable electrocatalytic properties for the reduction several compounds. peak potentials recorded these...

The mechanism of reductive cleavage model alkyl halides (methyl 2-bromoisobutyrate, methyl 2-bromopropionate, and 1-bromo-1-chloroethane), used as initiators in living radical polymerization (LRP), has been investigated acetonitrile using both experimental computational methods. Both theoretical investigations have revealed that dissociative electron transfer to these proceeds exclusively via a concerted rather than stepwise manner. all three requires substantial activation barrier stemming...

Polymerization of acidic monomers is one the biggest challenges for atom transfer radical polymerization (ATRP). An intramolecular cyclization reaction leading to loss C–X chain-end functionality was found be main reason partial termination growing polymer chains. Three approaches were used overcome this problem: using Cl as halogen, lowering pH (to 0.9), and increasing rate. Methacrylic acid (MAA) polymerized by both electrochemically mediated ATRP supplemental activator reducing agent up...

The thermodynamic properties of some copper complexes, among those frequently used as catalysts in controlled/living radical polymerization, has been studied CH3CN + 0.1 M (C2H5)4NBF4. A combination different techniques, namely potentiometry, spectrophotometry and cyclic voltammetry, to determine the stability constants all possible complexes CuI CuII present binary ternary systems composed or CuII, a halide ion (X = Cl−, Br−) polyamine ligand (L pentamethyldiethylenetriamine,...

Atom transfer radical polymerization (ATRP) in water is characterized by very high catalytic activity, i.e. the rate constant (kact) of "activation" reaction between CuI complexes and alkyl halides (RX) large. To accurately study such fast reactions water, we developed a collection electrochemical methods applicable for determination vast range kact values (>7 orders magnitude). These included constants extremely with > 107 mol–1 dm3 s–1. We studied three widely used ATRP catalysts...

ADVERTISEMENT RETURN TO ISSUEPREVNoteNEXTHarnessing the Interaction between Surfactant and Hydrophilic Catalyst To Control eATRP in MiniemulsionMarco Fantin†, Paweł Chmielarz‡†, Yi Wang†, Francesca Lorandi§†, Abdirisak A. Isse§, Armando Gennaro§, Krzysztof Matyjaszewski*†View Author Information† Department of Chemistry, Carnegie Mellon University, 4400 Fifth Avenue, Pittsburgh, Pennsylvania 15213, United States‡ Physical Faculty Rzeszow University Technology, Al. Powstan ́ców Warszawy 6,...