High Molecular Weight Polyacrylamides by Atom Transfer Radical Polymerization: Enabling Advancements in Water-Based Applications

Through the use of copper (I) chloride (CuCl) and tris(2-dimethylaminoethyl) amine (Me-6-TREN) as a metal/ligand pair, conditions for the robust, fast, and controlled radical polymerization of high molecular weight N-hydroxyethylacrylamide (HEAm), N-isopropylacrylamide (NIPAm), N,N'-dimethylacrylamide (DMAm), and acrylamide (Am) at ambient temperature are reported. Linear evolution of molecular weight and narrow molecular weight distribution was observed for all monomers with degrees of polymerization ranging from 50 to 5000. Random copolymers of several acrylamide-based monomers are also reported with excellent control over molecular weight and polydispersity. Characterization of high molecular weight poly (NIPAm) demonstrated large changes in the lower critical solution temperature observed on heating and cooling, and this hysteresis was exploited for the controlled release of doxorubicin from poly(NIPAm) spheres. This study represents the first example of preparation of high molecular weight acrylamide polymers by a metal-mediated controlled radical polymerization technique. Access to these materials, as well as to NIPAm polymers in particular, opens new doors for interesting applications in a variety of fields including tissue engineering, drug delivery, and controlled solution viscosity. (C) 2011 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 50: 181-186, 2012