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The polymerization of N,N-dimethylacrylamide (DMA) under atom transfer radical polymerization (ATRP) conditions was studied. The ligand, solvent (water, n-butanol, and toluene), initiator, and Cu halide were varied. High monomer conversions were obtained using the Me4Cyclam ligand. Polymerizations in water that were initiated at room temperature were complete within minutes. However, none of the experimental conditions produced a controlled polymerization. This conclusion is based on broad molecular weight distributions, poor agreement between theoretical and experimental M n, incremental monomer addition experiments, and end group analysis. We believe that the Cu salts complex to the amide group of the chain ends and stabilize the radical. This stabilization retards the deactivation step in ATRP and produces an unacceptably high concentration of radicals which leads to spontaneous termination reactions. In addition, we have indirect evidence for a cyclization reaction involving nucleophilic Br displacement by the penultimate amide nitrogen; this cyclic onium intermediate undergoes hydrolysis to form a hydroxy-terminated polymer.

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We describe polymer diffusion measurements in a poly(vinyl acetate) copolymer latex film by fluorescence decay measurements of nonradiative energy transfer (FRET). The base monomer is a 4:1 weight ratio copolymer of vinyl acetate and butyl acrylate P(VAc-BA) with a glass transition temperature of ca. 12 °C. P(VAc-BA) latex particles labeled with phenanthrene (Phe) as the donor and with 4-(N,Ndimethylamino)benzophenone (NBen) as the acceptor were prepared by semicontinuous emulsion polymerization. Latex films were cast from a 1:1 mixture of Phe-and NBen-labeled latex samples. First, a series of films containing NBen-labeled latex samples with different NBen levels were annealed at 45 °C, showing that NBen levels have no influence on the rate of polymer diffusion in P(VAc-BA) latex films. From the fully mixed solvent-cast films, the characteristic distance for energy transfer between Phe and NBen (the Fo ¨rster radius R0) was obtained as 2.44 nm. Then, polymer diffusion was monitored as a function of annealing temperature in latex films containing Phe-labeled latex with 1 mol % PheMA and NBen-labeled latex with 0.3 mol % of the NBen chromophore. The temperature dependence of the diffusion rate (from 35 to 75 °C) was characterized by an effective activation energy Ea ) 34 ( 0.5 kcal/ mol. In parallel, an effective Ea ) 34 kcal/mol was obtained from viscoelastic relaxation measurements over a range of temperatures close to those of the diffusion experiments.