Atom Transfer Radical Polymerization of Methyl Methacrylate at Ambient Temperature Using Soluble Cu(I) Complex Catalysts Formed with Mixed Ligands of Multidentate Amines and Halide Ions DHRUBA P. CHATTERJEE, UMA CHATTERJEE, BROJA M. MANDAL Polymer Science Unit, Indian Association for the Cultivation of Science, Jadavpur, Kolkata 700032, India Received 8 January 2004; accepted 11 March 2004 DOI: 10.1002/pola.20182 Published online in Wiley InterScience (www.interscience.wiley.com). ABSTRACT:: The addition of soluble quaternaryammonium halides (QX) in catalytic amounts takes into solution CuX/pentamethyldiethylenetriamine (PMDETA) complex (X = Cl, Br) in methyl methacrylate (MMA). The soluble catalyst complex provided much better control of the polymerization of MMA at ambient temperature than did the insoluble catalyst formed in the absence of QX, with CuCl/PMDETA/Aliquat  336 (AQCl) proving to be superior to the CuBr/PMDETA/Bu 4 NBr catalyst system. The effect was independent of the size of the quaternaryammonium ion. Also, the presence of Cl in the catalyst–QX combination either as CuCl or as QCl was enough to give much better control than that provided by a wholly Br-based system. Among the various initiators used, that is, ethyl 2-bromoisobutyrate (EBiB), methyl 2-bromopropionate (MBP), 1-phenylethyl bromide (PEBr), and p-toluenesulfonyl chloride (pTsCl), only EBiB gave a satisfactory result. With MBP and PEBr the initiation was slower than the propagation, whereas with pTsCl the initiation was very fast, so that instantaneous termination occurred. The living nature of the polymers was shown by block copolymer preparation. It has been suggested that some of the added halide ions entered into the coordination spheres of Cu(I) and Cu(II), leading to their improved solubility and stronger deactivation by the Cu(II) complex. © 2004 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 42: 4132– 4142, 2004 Keywords: atom transfer radical polymerization (ATRP); living polymerization; phase transfer catalysis; methyl methacrylate; poly(methyl methacrylate); block copol- ymers INTRODUCTION Atom transfer radical polymerization (ATRP) has proved to be effective for the living radical poly- merization (LRP) of a variety of monomers such as styrene, (meth)acrylates, acrylonitrile, and (meth)acrylamides. 1 It works on the “persistent radical effect” principle, according to which a transition metal complex of a higher oxidation state acts as the persistent radical to reversibly deactivate a growing polymer radical to form a dormant polymer molecule with a labile carbon halogen bond at the chain end. 2–5 Appropriate ligands and transition metal salts may suitably adjust the equilibrium position of reversible deac- tivation so that the polymer radical concentration becomes good enough for a reasonably fast ATRP. Correspondence to: B. M. Mandal (E-mail: psubmm@mahendra.iacs.res.in) Journal of Polymer Science: Part A: Polymer Chemistry, Vol. 42, 4132– 4142 (2004) © 2004 Wiley Periodicals, Inc. 4132