Ambient-temperature copper-catalyzed atom transfer radical polymerization of methacrylates in ethylene glycol solvents

The use of ethylene glycol solvents in the room-temperature atom transfer radical polymerization (ATRP) of various hydrophobic and hydrophilic methacrylates is demonstrated. Unlike many of the very polar solvents described in the literature for room-temperature ATRP, these solvents have good solvency for a wide range of polymers and monomers and are cheap and relatively nontoxic. Ethylene glycols with one hydroxyl and one methoxy group, such as tri(ethylene glycol) monomethyl ether (TEGMME), provide optimal results. The polymerization of methyl methacrylate in TEGMME with CuBr/NNN'N',N-pentamethyldiethylenetriamine as the catalyst requires the addition of CuCl, at the beginning of the reaction to produce well-controlled polymerizations. This leads to polymers with predictable molecular weights and relatively narrow polydispersities. Polymerization in solvents that are fully methoxy-capped terminate prematurely because of catalyst precipitation. The electrochemical behavior of copper complexes in selected solvents is examined to determine why these solvents provide good rates at room temperature. (c) 2005 Wiley Periodicals, Inc.