title: Highly active copper-based catalyst for atom transfer radical polymerization.
abstract: 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 KATRP (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.
authors.affiliation: Soft Materials Laboratory, Department of Chemical & Petroleum Engineering, University of Wyoming, Laramie, Wyoming 82071, USA.
authors.forename: Huadong
authors.initials: H
authors.lastname: Tang
authors.forename: Navamoney
authors.initials: N
authors.lastname: Arulsamy
authors.forename: Maciej
authors.initials: M
authors.lastname: Radosz
authors.forename: Youqing
authors.initials: Y
authors.lastname: Shen
authors.forename: Nicolay V
authors.initials: NV
authors.lastname: Tsarevsky
authors.forename: Wade A
authors.initials: WA
authors.lastname: Braunecker
authors.forename: Wei
authors.initials: W
authors.lastname: Tang
authors.forename: Krzysztof
authors.initials: K
authors.lastname: Matyjaszewski