Atom transfer radical polymerization.

Metal-catalyzed living radical polymerization.

Controlled/living radical polymerization: Features, developments, and perspectives

Current status and future perspectives in atom transfer radical polymerization (ATRP) are presented. Special emphasis is placed on mechanistic understanding of ATRP, recent synthetic and process development, and new controlled polymer architectures enabled by ATRP. New hybrid materials based on organic/inorganic systems and natural/synthetic polymers are presented. Some current and forthcoming applications are described.

Atom Transfer Radical Polymerization (ATRP): Current Status and Future Perspectives

Keywords: Fragmentation Chain-Transfer ; Self-Assembled Monolayers ; Walled Carbon Nanotubes ; Well-Defined Polymer ; Nitroxide-Mediated Polymerization ; Block-Copolymer Brushes ; Poly(Methyl Methacrylate) Brushes ; Transfer Raft Polymerization ; Quartz-Crystal Microbalance ; Poly(Acrylic Acid) Brushes Reference EPFL-REVIEW-148464doi:10.1021/cr900045aView record in Web of Science Record created on 2010-04-23, modified on 2017-05-10

Polymer Brushes via Surface-Initiated Controlled Radical Polymerization: Synthesis, Characterization, Properties, and Applications

Synthesis of Well-Defined Polyacrylonitrile by Atom Transfer Radical Polymerization

Atom transfer radical polymerization has been used to successfully synthesize polyacrylonitrile (PAN) with predictable molecular weights and narrow polydispersities. This was achieved by using CuX/2,2‘-bipyridine (X = Br or Cl) as the catalyst, 2-halopropionitriles as initiators, and ethylene carbonate as a solvent. Monomer consumption showed significant curvature in the first-order kinetic plot, indicating termination is present. 1H NMR spectroscopy showed that the halide end group is irreversibly removed during the polymerization. Possible reasons for this reaction are given, with the most probable being the reduction of the radical by CuIX to form an anion that subsequently deactivates very quickly. Such side reactions limit the molecular weight achievable to Mn < 30 000 while still keeping low polydispersity, Mw/Mn < 1.5.

An Investigation into the CuX/2,2‘-Bipyridine (X = Br or Cl) Mediated Atom Transfer Radical Polymerization of Acrylonitrile

The kinetic parameters for the activation and deactivation steps in ATRP for Cu-based catalysts were determined with eight different tridentate nitrogen-based ligands. Additionally, the redox properties of these Cu complexes were measured by cyclic voltammetry. By correlating the kinetic parameters of the activation and deactivation steps with the reduction potential of the Cu(II) complexes, it was found that more reducing Cu catalysts form faster activating Cu(I) and slower deactivating Cu(II) species. The rate of activation depends on the nature of the N-binding site of the ligand. Ligands with alkyl amine or pyridine binding sites form the fastest activating catalysts. The phenyl-substituted ligands form very slowly activating and very rapidly deactivating catalysts. Slower deactivation rates were found for catalysts with a central pyridine unit in the ligand than for catalysts derived from ligands with a central amine unit. In general, the activity of the ligands decreases in the following order:  alk...

Tridentate Nitrogen-Based Ligands in Cu-Based ATRP: A Structure−Activity Study

Immobilization of the catalyst system for atom transfer radical polymerization (ATRP) on various silica and cross-linked polystyrene supports was studied. The catalyst system comprises a copper halide, complexed by various amines. The effect of size of support particles, the amount of immobilized catalyst, and the addition of Cu(II) species as deactivator in the polymerization were investigated. In all cases, polymerization occurred, but generally the reactions were not as well controlled in terms of molecular weight and polydispersities as homogeneous systems. The molecular weights did not match the predicted values, and polydispersities were high (1.5 < Mw/Mn < 10). However, control was improved by either an increase in catalyst concentration or the addition of deactivator still bound to support to the system. Potential reasons for the reduced control could be the low mobility of the supported catalyst and/or the steric hindrance and incompatibilities between the immobilized catalyst and the polymer cha...

Immobilization of the Copper Catalyst in Atom Transfer Radical Polymerization

The kinetics of atom transfer radical polymerization (ATRP) of methyl acrylate (MA) is discussed. MA polymerizations were carried out under homogeneous conditions using CuBr/4,4‘-di(5-nonyl)-2,2‘-bipyridine (dNbpy) as the catalyst. Plots of ln([M]o/[M]) vs time and molecular weight evolution vs conversion showed a linear dependence, indicating a constant number of propagating species throughout the polymerization as well as a negligible contribution of termination or transfer reactions. The dependence of the rate of polymerization on the concentrations of initiator, catalyst, Cu(II), and temperature are presented. The equilibrium constant between active and dormant species, Keq = 1.2 × 10-9 at 90 °C is much smaller than in the ATRP of styrene or methyl methacrylate. On the basis of an Arrhenius plot, the apparent enthalpy of activation for homogeneous ATRP of MA ΔH‡app = 27.5 kcal/mol corresponds to an enthalpy of equilibrium ΔH0eq = 23 kcal/mol, which is much higher than in the ATRP of styrene or methyl ...

Hyun-Jong Paik

Papers

Synthesis of Well-Defined Polyacrylonitrile by Atom Transfer Radical Polymerization

An Investigation into the CuX/2,2‘-Bipyridine (X = Br or Cl) Mediated Atom Transfer Radical Polymerization of Acrylonitrile

Tridentate Nitrogen-Based Ligands in Cu-Based ATRP: A Structure−Activity Study

Immobilization of the Copper Catalyst in Atom Transfer Radical Polymerization

Kinetic investigation of the atom transfer radical polymerization of methyl acrylate