Highly Active Copper-Based Catalyst for Atom Transfer Radical Polymerization

• Published in: Journal of the American Chemical Society Vol. 128; no. 50; pp. 16277 - 16285
• Main Authors: Tang, Huadong, Arulsamy, Navamoney, Radosz, Maciej, Shen, Youqing, Tsarevsky, Nicolay V, Braunecker, Wade A, Tang, Wei, Matyjaszewski, Krzysztof
• Format: Journal Article
• Language: English
• Published: WASHINGTON American Chemical Society 20.12.2006; Amer Chemical Soc
• Subjects: Catalysis; Catalysts: preparations and properties; Chemistry; Chemistry, Multidisciplinary; Coordination compounds; Exact sciences and technology; General and physical chemistry; Inorganic chemistry and origins of life; Physical Sciences; Preparations and properties; Science & Technology; Theory of reactions, general kinetics. Catalysis. Nomenclature, chemical documentation, computer chemistry; AQUEOUS-SOLUTIONS; PYRIDINE-DERIVATIVES; ELECTRON-TRANSFER; GRAFT-COPOLYMERS; METHYL-METHACRYLATE; RING-OPENING POLYMERIZATION; ACTIVATION RATE CONSTANTS; METAL-COMPLEXES; UNIVERSAL CALIBRATION; LINEAR BLOCK-COPOLYMERS; Complexation; Chemical solution; Equilibrium constant; Transition element complexes; Stability; Molecular structure; Polymer; NMR spectrometry; Copper complex; X ray diffraction; Free radical polymerization; Copper ion; Dinuclear complex; Copper I Bromides; Solvent; Catalyst; Acrylic acid derivatives; Crystalline structure
• ISSN: 0002-7863; 1520-5126
• DOI: 10.1021/ja0653369

Atom transfer radical polymerization (ATRP) generally requires a catalyst/initiator molar ratio of 0.1 to 1 and catalyst/monomer molar ratio of 0.001 to 0.01 (i.e., catalyst concentration:  1000−10 000 ppm versus monomer). Herein, we report a new copper-based complex CuBr/N,N,N ‘,N ‘-tetrakis(2-pyridylmethyl)ethylenediamine (TPEN) as a versatile and highly active catalyst for acrylic, methacrylic, and styrenic monomers. The catalyst mediated ATRP at a catalyst/initiator molar ratio of 0.005 and produced polymers with well-controlled molecular weights and low polydispersities. ATRP occurred even at a catalyst/initiator molar ratio as low as 0.001 with copper concentration in the produced polymers as low as 6−8 ppm (catalyst/monomer molar ratio = 10-5). The catalyst structures were studied by X-ray diffraction and NMR spectroscopy. The activator CuIBr/TPEN existed in solution as binuclear and mononuclear complexes in equilibrium but as a binuclear complex in its single crystals. The deactivator CuIIBr2/TPEN complex was mononuclear. High stability and appropriate K ATRP (ATRP equilibrium constant) were found crucial for the catalyst working under high dilution or in coordinating solvents/monomers. This provides guidance for further design of highly active ATRP catalysts.