The concept of initiators for continuous activator regeneration (ICAR) in atom transfer radical polymerization (ATRP) is introduced, whereby a constant source organic free radicals works to regenerate the Cu I activator, which otherwise consumed termination reactions when used at very low concentrations. With this technique, controlled synthesis polystyrene and poly(methyl methacrylate) ( M w / n < 1.2) can be implemented with catalyst concentrations between 10 50 ppm, where its removal...

Equilibrium constants in Cu-based atom transfer radical polymerization (ATRP) were determined for a wide range of ligands and initiators acetonitrile at 22 °C. The ATRP equilibrium obtained vary over 7 orders magnitude strongly depend on the ligand initiator structures. activities CuI/ligand complexes are highest tetradentate ligands, lower tridentate lowest bidentate ligands. Complexes with tripodal bridged (Me6TREN cyclam) tend to be more active than those corresponding linear largest...

Several synthetic methods have recently emerged to develop high-surface-area solid-state organic framework-based materials into free-flowing liquids with permanent porosity. The fluidity of these porous liquid (PL) provides them advantages in certain storage and transport processes. However, most necessitate the use cryogenic temperatures store weakly bound gases such as H2, where PLs lose their fluidity. Covalent framework (COF)-based that could reversibly form stable complexes H2 near...

Several propositions have been made about the mechanism in which Cu0 mediates controlled radical polymerization that include (1) exclusive activation of an alkyl halide initiator by exceptionally active to generate a propagating and CuI species, (2) instantaneous disproportionation into CuII "catalytic" solvents such as DMSO, (3) deactivation establish equilibrium between dormant polymer chains. It was further postulated processes this technique, entitled single-electron-transfer living...

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...

Atom transfer radical polymerization (ATRP) generally requires a catalyst/initiator molar ratio of 0.1 to 1 and catalyst/monomer 0.001 0.01 (i.e., catalyst concentration: 1000-10,000 ppm versus monomer). Herein, we report new copper-based complex CuBr/N,N,N',N'-tetrakis(2-pyridylmethyl)ethylenediamine (TPEN) as versatile highly active for acrylic, methacrylic, styrenic monomers. The mediated ATRP at 0.005 produced polymers with well-controlled molecular weights low polydispersities. occurred...

A method is discussed for quantifying and categorizing the activity of an atom transfer radical polymerization (ATRP) catalyst as being derived from product its intrinsic reducing power affinity halide anions. The several copper, ruthenium, osmium ATRP catalysts was quantified with cyclic voltammetry in tetrahydrofuran, including MtX2(PPh3)3, MtX(Cp*)PiPr3, CuX(BPMODA) (where Mt = Ru Os, X Cl Br, BPMODA N,N-bis(2-pyridylmethyl)octadecylamine). Spectrophotometric measurements were used to...

Direct air capture (DAC) technology is being explored as a pathway for reducing greenhouse gas emissions through the efficient removal of CO2 from atmosphere. However, there remains knowledge gap regarding structure–property–performance factors that impact behavior these systems in diverse, real-world environments. In aminopolymer-based DAC systems, diffusion tightly coupled with polymer mobility, which turn affected by large matrix variables, including interactions pore wall support,...

The successful ATRP of a coordinating monomer, 4-vinylpyridine (4VP), in aqueous media at 30 °C is reported. In the presence basic and nucleophilic monomers such as 4VP, use chloride-containing initiating/catalytic system essential to achieve good polymerization control narrow molecular weight distribution. This due significantly slower reaction monomer or polymer with secondary alkyl chloride-type dormant chain ends compared their bromide counterparts. When bromide-based was used, obtained...

ADVERTISEMENT RETURN TO ISSUEPREVCommunication to the...Communication the EditorNEXTOsmium-Mediated Radical PolymerizationWade A. Braunecker, Yujiro Itami, and Krzysztof MatyjaszewskiView Author Information Department of Chemistry, Carnegie Mellon University, 4400 Fifth Avenue, Pittsburgh, Pennsylvania 15213 Cite this: Macromolecules 2005, 38, 23, 9402–9404Publication Date (Web):October 20, 2005Publication History Received26 August 2005Revised7 October 2005Published online20 inissue 1...

A series of new donor–acceptor π-conjugated copolymers incorporating 5,10-dihydroindolo[3,2-b]indole (DINI) as an electron donating unit have been designed, synthesized, and explored in bulk heterojunction solar cells with diketopyrrolopyrrole thienopyrroledione the accepting units. significant effect size shape pendant alkyl substituents attached to DINI on optical electronic properties is described. Our study reveals a good correlation between theoretical calculations performed selected...

Controlling steric interactions between neighboring repeat units in donor–acceptor (D–A) alternating copolymers can positively impact morphologies and intermolecular electronic necessary to obtain high performances organic photovoltaic (OPV) devices. Herein, we design synthesize 12 new conjugated D–A copolymers, employing ethynylene linkages for this control. We explore combinations of fluorene, benzodithiophene, diketopyrrolopyrrole with analogues pyromellitic diimide, thienoisoindoledione,...

Conjugated alternating copolymers were designed with low optical band gaps for organic photovoltaic (OPV) applications by considering quinoid resonance stabilization. Copolymers of thienoisoindoledione (TID) and benzodithiophene (BDT) had appreciably lower (by ∼0.4 eV) than thienopyrroledione (TPD) BDT. In addition to intramolecular charge transfer stabilization (i.e., the "push-pull" effect), former copolymer's structure is stabilized a gain in aromatic energy isoindole unit. Additionally,...

Colloidal COFs suspended in a bulky, size-excluded ionic liquid create ‘porous liquid’ with enhanced gas uptake.

ADVERTISEMENT RETURN TO ISSUEPREVCommunication to the...Communication the EditorNEXTDetermination of Rate Constants for Activation Step in Atom Transfer Radical Polymerization Using Stopped-Flow TechniqueTomislav Pintauer, Wade Braunecker, Edmond Collange, Rinaldo Poli, and Krzysztof MatyjaszewskiView Author Information Department Chemistry, Carnegie Mellon University, 4400 Fifth Avenue, Pittsburgh, Pennsylvania 15213; Laboratoire de Synthèse et d'Electrosynthèse Organométalliques, Faculté...

Abstract With the recent development of new initiation techniques in atom transfer radical polymerization (ATRP) that allow catalysts to be employed at unprecedented low concentrations (∼10 ppm), a thorough understanding competitive equilibria can affect catalyst performance is becoming increasingly important. Such mechanistic considerations are discussed herein, including i) factors affecting position ATRP equilibrium; ii) dissociation high dilution and loss deactivator due halide...

The relationship between the polymer network and electronic transport properties for stable radical polymeric materials has come under investigation owing to their potential application in devices. For poly(2,2,6,6-tetramethylpiperidine-4-yl-1-oxyl methacrylate), it is unclear whether packing optimal charge partially because molecular structure not well-understood. Using paramagnetic nitroxide as a probe of synthetic techniques control concentration on methyl methacrylate backbone, we...

A series of covalent organic framework (COF) structures is synthesized that possesses a tunable density covalently bound nitroxyl radicals within the COF pores. The highest produces an electron paramagnetic resonance (EPR) signal suggests majority strongly interact with other radicals, whereas for smaller loadings EPR signals indicate are primarily isolated but restricted motion. dielectric loss as determined from microwave absorption compared amorphous control free motion inhibited when...

A two-dimensional imine-based covalent organic framework (COF) was designed and synthesized such that phenyl perfluorophenyl structural units can seamlessly alternate between layers of the framework. X-ray diffraction COF powders reveals a striking increase in crystallinity for with self-complementary phenyl/perfluorophenyl interactions (FASt-COF). Whereas measured values Brunauer–Emmet–Teller (BET) surface areas nonfluorinated Base-COF employing hydrogen bonding were ∼37% 59%, respectively,...

Copper(II) formate is efficiently incorporated into the pores of a 2D imine-based covalent organic framework (COF) via coordination with phenol and imine groups. The coordinated metal ion then reduced to Cu(I) thermal treatment that evolves CO2. After loading hydrogen gas, majority H2 desorbs from coordinatively saturated Cu(II) COF at temperatures < −100 °C. However, activated retains adsorbed above room temperature. Adsorption/desorption was highly reversible. Diffuse reflectance infrared...