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Binding parameters for the interactions of pentagalloyl glucose (PGG) and four hydrolyzable tannins (representing gallotannins and ellagitannins) with gelatin and bovine serum albumin (BSA) have been determined from isothermal titration calorimetry data. Equilibrium binding constants determined for the interaction of PGG and isolated mixtures of tara gallotannins and of sumac gallotannins with gelatin and BSA were of the same order of magnitude for each tannin (in the range of 10(4)-10(5) M(-1) for stronger binding sites when using a binding model consisting of two sets of multiple binding sites). In contrast, isolated mixtures of chestnut ellagitannins and of myrabolan ellagitannins exhibited 3-4 orders of magnitude greater equilibrium binding constants for the interaction with gelatin (approximately 2 x 10(6) M(-1)) than for that with BSA (approximately 8 x 10(2) M(-1)). Binding stoichiometries revealed that the stronger binding sites on gelatin outnumbered those on BSA by a ratio of at least approximately 2:1 for all of the hydrolyzable tannins studied. Overall, the data revealed that relative binding constants for the interactions with gelatin and BSA are dependent on the structural flexibility of the tannin molecule.

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Polymerization of methyl acrylate (MA) catalyzed by Cu(0) is carried out in toluene using a range of alcohols and phenol as additives to facilitate the reaction. The polar/coordinating additives promote disproportionation of Cu(I) to Cu(0), the proposed active species in single electron transfer living radical polymerization (SET‐LRP), and Cu(II) whilst toluene maintains solubility of the reagents and products. In this work, the use of alcohols as additives is optimized. Polymerizations are monitored in real time using rapid chromatography to obtain conversion and molecular weight distribution data without the necessity of manual sampling. Rapid gel permeation chromatography with low angle laser light scattering detection is shown to be a viable method of obtaining molecular weight distribution data in real time compared with conventional analytical techniques. Moreover, the changes in CuBr2 concentration during SET‐LRP reactions are monitored online using a photodiode array detector. Finally, the kinetics of SET‐LRP of MA using an ultra pure highly porous Cu(0) is performed and a detailed discussion on the role of Cu(II) is provided. © 2011 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2011

The polymerization of styrene mediated by copper/N-n-alkyl-2-pyridylmethanimine is reported. Two different types of initiator were employed, viz., 1-phenylethyl bromide, chosen for its similar structure to the final end group of the polymer, and alkyl-2-bromisobutyrates, as models for the synthesis of diblock copolymers via macroinitiators. The copper catalyst structure was varied by changing the alkyl group on the N-n-alkyl-2-pyridylmethanimine ligand where alkyl = propyl (3), pentyl (4), and octyl (5) and used over a temperature range of 90−130 °C. At 90 °C, polymerization reactions were relatively slow with polymerization taking approximately 7 days to reach 100% conversion, 12 h to reach 36% conversion at 110 °C, and 7 h to reach 90% conversion at 130 °C. The PDI of the polymer broadens on increasing the temperature, reaching 1.15, 1.17, and 1.32 at 90, 110, and 130 °C, respectively, when the reaction was stopped. Thus, 110 °C is the optimal temperature for the polymerization of styrene with this type of ligand. The catalyst prepared with N-n-propyl-2-pyridylmethanimine is not completely soluble over all temperatures, and the catalyst solubility affects both the rate and the control of the polymerization. As the length of the alkyl chain increases, the solubility in nonpolar solvent also increases. Hence, N-n-pentyl-2-pyridylmethanimine is the best ligand for copper bromide to ensure homogeneity of the reaction and achieve good control over the polymerization. The effect of the solvent polarity was also investigated to elaborate the optimal polymerization conditions using xylene, anisole, and ethylene glycol diethyl ether. Based on these results, the synthesis of di- and triblock copolymers was undertaken using respectively poly(ethylene glycol) methyl ether and poly(propylene glycol) derived initiators. The latter led to an amphiphilic block copolymer with a low PDI = 1.27 and a molecular weight close to the theoretical value (M n SEC = 10 900 mol g-1). A large batch (40 g) of block copolymer was synthesized with a block of PS = 5000 g mol-1 by stopping the reaction at 50% conversion, which had [St]/[I] = 100.