嵌段共聚物的研究.pdf

Macromolecules 1999, 32, 5199 Homogeneous Reverse Atom Transfer Radical Polymerization of Styrene Initiated by Peroxides Jianhui Xia and Krzysztof Matyjaszewski* Center for Macromolecular Engineering, Department of Chemistry, Carnegie Mellon University, 4400 Fifth Avenue, Pittsburgh, Pennsylvania 15213 Received January 12, 1999; Revised Manuscript Received May 19, 1999 ABSTRACT: The homogeneous reverse atom transfer radical polymerization (ATRP) of styrene was initiated by benzoyl peroxide (BPO) in the presence of CuBr or CuBr2 complexed by 4,4′-di(5-nonyl)-2,2′- bipyridine (dNbpy). In contrast to the successful reverse ATRP initiated by azobis(isobutyronitrile) (AIBN) and CuBr /2dNbpy, no control of polymerization was observed for the BPO/CuBr /2dNbpy system. 2 2 However, controlled/“living” polymerization was observed when BPO was used together with CuBr/2dNbpy. The differences between the BPO and AIBN systems are ascribed to the electron transfer and the formation of copper benzoate species. Atom transfer radical polymerization (ATRP) is among and Mw/Mn 2.6 was obtained in 66% yield after 1 h at the most promising approaches to controlled radical 110 °C. A similar result was obtained in the presence polymerization.13 Copper-mediated ATRP has been of CuBr/2dNbpy, indicating no appreciable interaction successfully used to prepare polymers with predeter- of the salt with either the radicals or AIBN. When the mined molecular weights, low polydispers