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In this study, polyacrylamide nanocomposite hydrogels were formulated in combination with sodium montmorillonite (MMT) in the presence of a 2-T magnetic field. This top-down nanomanufacturing approach led to interesting changes in the internal structure of the gel and ultimately to a dramatic improvement in the ability of the composite to separate the two protein probes, ovum serum albumin and carbonic anhydrase. The morphology of the nanocomposite hydrogel was analyzed with cryogenic scanning and transmission electron microscopy, wide-angle X-ray diffraction, and small-angle scattering to determine whether morphological changes would correlate with this improved separation. As the volume fractions of MMT were well under 1% in this study (because of aqueous swelling), scattering data were dominated by the polymer structure. Significant morphological changes were noted at two length scales: (1) the hydrogel cell structure, at hundreds of nanometers, appeared to exhibit changes in the anisotropic orientation with magnetization, and (2) the polyamide structure, at tens of nanometers, exhibited decreasing pore size (small-angle X-ray scattering). The separation data correlated most closely with a reduction in pore size; however, an additional contribution to separation from local electrostatic effects from the presence of charged MMT in the cell walls could not be discounted. The change in the pore size associated with processing may have been due to the MMT presence altering the diffusion rates of the reactants during polymer formation. The method demonstrated herein could be used ultimately to separate proteins in their native state, with the potential retention of function for downstream applications, such as novel detection techniques or purification. © 2012 Wiley Periodicals, Inc. J Appl Polym Sci, 2012

Amphiphilic tris(2,2′-bipyridine)ruthenium-cored star-shaped polymers consisting of one polystyrene block and two poly(N-isopropylacrylamide) blocks were prepared by the “arm-first” method in which RAFT polymerization and nonconvalent ligand–metal complexation were employed. The prepared amphiphilic star-shaped metallopolymers are able to form micelles in water. The size and distribution of the micelles were studied by dynamic light scattering and transmission electron microscopy techniques. Preliminary studies indicate that the polymer concentration and the hydrophilic poly(N-isopropylacrylamide) block length can affect the morphologies of the formed metal-interfaced core–shell micelles in water. © 2007 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 45: 4204–4210, 2007

A new bipyridine-functionalized dithioester was synthesized and further used as a RAFT agent in RAFT polymerization of styrene and N-isopropylacrylamide. Kinetics analysis indicates that it is an efficient chain transfer agent for RAFT polymerization of the two monomers which produce polystyrene and poly(N-isopropylacrylamide) polymers with predetermined molecular weights and low polydispersities in addition to the end functionality of bipyridine. The bipyridine end-functionalized polymers were further used as macroligands for the preparation of star-shaped metallopolymers. Hydrophobic polystyrene macroligand combined with hydrophiphilic poly(N-isopropylacrylamide) was complexed with ruthenium ions to produce amphiphilic ruthenium-cored star-shaped metallopolymers. The structures of these synthesized metallopolymers were further elucidated by UV–vis, fluorescence, size exclusion chromatography (SEC), and differential scanning calorimetry (DSC) as well as NMR techniques. © 2007 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 45: 4225–4239, 2007

Two-dimensional (2D) and three-dimensional (3D) magnetic cobalt nanowire thin films with tunable 3−10 nm wire diameters have been electrodeposited using mesoporous silica templates containing 2D hexagonal or 3D cubic pore channels. As compared to bulk cobalt films, the cobalt nanowire thin films exhibit enhanced coercivities and controllable magnetic anisotropy through tuning of the mesostructure and dimension of the nanowires. Such novel magnetic nanowire thin films may provide a new platform for high-density information storage applications.