New polymer synthesis by nitroxide mediated living radical polymerizations.

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

Chemical Reviews is published by the American Chemical Society. 1155 Sixteenth Street N.W., Washington, DC 20036 “Green” Atom Transfer Radical Polymerization: From Process Design to Preparation of Well-Defined Environmentally Friendly Polymeric Materials Nicolay V. Tsarevsky, and Krzysztof Matyjaszewski Chem. Rev., 2007, 107 (6), 2270-2299• DOI: 10.1021/cr050947p • Publication Date (Web): 27 May 2007 Downloaded from http://pubs.acs.org on April 2, 2009

"Green" atom transfer radical polymerization: from process design to preparation of well-defined environmentally friendly polymeric materials.

The persistent radical effect: a principle for selective radical reactions and living radical polymerizations.

3.10 - Nitroxide-Mediated Polymerization

The bulk polymerization of styrene at 125 °C in the presence of a PS−TEMPO adduct was studied with respect to the polymerization rate and the concentration of free TEMPO as a function of time, where PS is polystyrene and TEMPO is 2,2,6,6-tetramethylpiperidinyl-1-oxy. The results were perfectly consistent with the proposed kinetic scheme which assumes the existence of a stationary state with respect to both polymeric and nitroxyl radical concentrations and predicts that the polymerization rate of the nitroxide-mediated system is independent of the adduct concentration, being equal to the polymerization rate of the adduct-free system, i.e., the rate of thermal polymerization in the case of the styrene system studied here. The equilibrium constant K for the PS−TEMPO reversible reaction was estimated to be 2.1 × 10-11 mol L-1 on the basis of the dilatometric and electron spin resonance data. This value of K was indicated to be large enough to set the system under control. This work thus shows that in order fo...

Mechanisms and kinetics of nitroxide-controlled free radical polymerization

Kinetic study on the activation process in an atom transfer radical polymerization

Herein, a new reaction of an alkyl iodide (R–I) with an azide anion (N3–) to reversibly generate the corresponding alkyl radical (R•) is reported. Via this new reaction, N3– was used as an efficient catalyst in living radical polymerization, yielding a well-defined polymer–iodide. A particularly interesting finding was the solvent selectivity of this reaction; namely, R–I and N3– generated R• in nonpolar solvents, while the substitution product R–N3 was generated in polar solvents. Exploiting this unique solvent selectivity, a one-pot synthesis of polymer–N3 was attained. N3– was first used as a catalyst for living radical polymerization in a nonpolar solvent to produce a polymer–iodide and was subsequently used as a substitution agent in a polar solvent by simply adding the polar solvent, thereby transforming the polymer–iodide to polymer–N3 in one pot. This one-pot synthesis was further applied to obtain N3-chain-end-functionalized polymer brushes on the surface, uniquely controlling the N3 coverage (nu...

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Solvent-Selective Reactions of Alkyl Iodide with Sodium Azide for Radical Generation and Azide Substitution and Their Application to One-Pot Synthesis of Chain-End-Functionalized Polymers

Molecular weight distribution of polymers, termed dispersity (Đ), is a fundamental parameter for determining polymer material properties. This paper reports a novel approach for controlling Đ by exploiting a temperature-selective radical generation in organocatalyzed living radical polymerization. The polymers with tailored Đ were synthesized in a batch system without the assistance of an external pump. A unique aspect of this approach is that Đ was tuneable from 1.11 to 1.50 in any segment in diblock, triblock, and multiblock copolymers and in any form of star and brush polymer without segmental or topological restriction. This approach is amenable to various monomers and free from metals and thus attractive for applications. The approach also generated polymer brushes on surfaces with tailored Đ. An interesting finding was that the polymer brushes exhibited unique interaction with external molecules, depending on the Đ value.

Polymer Dispersity Control by Organocatalyzed Living Radical Polymerization

Halogen exchange of alkyl bromide (R–Br) with sodium iodide (NaI) was used for the transformation of R–Br to alkyl iodide (R–I) in situ in organocatalyzed living radical polymerization (LRP). R–Br was employed as a starting compound (precursor), and the R–I formed in situ was employed as an initiating dormant species for the polymerization. The efficiency of the transformation significantly depends on the R group of R–Br. By the rational selection of the R group and reaction temperature along with the use of tetrabutylammonium iodide (Bu4NI) as a catalyst, low-polydispersity (Mw/Mn = 1.1–1.4) polymers were obtained with high conversions (e.g., 70–90%) in reasonably short periods of time (typically 3–10 h) in the polymerizations of methyl methacrylate, butyl acrylate, styrene, acrylonitrile, and functional methacrylates. Well-defined diblock and triblock copolymers and a chain-end functional polymer were also obtained. R–Br is generally much more stable than R–I upon storage. Various R–Br are commercially ...

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Atsushi Goto

Papers

Mechanisms and kinetics of nitroxide-controlled free radical polymerization

Kinetic study on the activation process in an atom transfer radical polymerization

Solvent-Selective Reactions of Alkyl Iodide with Sodium Azide for Radical Generation and Azide Substitution and Their Application to One-Pot Synthesis of Chain-End-Functionalized Polymers

Polymer Dispersity Control by Organocatalyzed Living Radical Polymerization

Organocatalyzed Living Radical Polymerization via in Situ Halogen Exchange of Alkyl Bromides to Alkyl Iodides