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Now showing items 1 - 2 of 2

  • Preparation of Ni-g-polymer core-shell nanoparticles by surface-initiated atom transfer radical polymerization RID C-3754-2012

    Chen, Renxu   Madaughlin, Shane   Botton, Gianluigi   Zhu, Shiping  

    Surface-initiated atom transfer radical polymerization (si-ATRP) technique was successfully employed to modify Ni nanoparticles with polymer shells. ATRP initiators were covalently bonded onto Ni nanoparticle surfaces by a combination of ligand exchange and condensation reactions. Various kinds of polymers including poly(methyl methacrylate) (PMMA) and poly(n-isopropylacrylamide) (PNIPAM) were grafted from the immobilized initiators. The grated polymer shells gave Ni nanoparticles exceptionally good dispersion and stability in solvents. Fourier transform infrared (FT-IR) spectroscopy, thermogravimetric analysis (TGA) and transmission electron spectroscopy (TEM) were employed to confirm the grafting and to characterize the nanoparticle core-shell structure. Gel permeation chromatography (GPC) studies of cleaved polymer chains revealed that the grafting polymerization was well controlled. The magnetic properties of Ni-g-polymer nanoparticles were also studied. (C) 2009 Elsevier Ltd. All rights reserved.
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  • Grafting Acrylic Polymers from Flat Nickel and Copper Surfaces by Surface-Initiated Atom Transfer Radical Polymerization

    Chen, Renxu   Zhu, Shiping   Maclaughlin, Shane  

    Acrylic polymers, including poly(methyl methacrylate), poly(2,2,2-trifluoroethyl methacrylate), poly(N,N'-dimethyaminoethyl methacrylate), and poly(2-hydroxyethyl methacrylate) were grafted from flat nickel and copper surfaces through surface-initiated atom transfer radical polymerization (ATRP). For the nickel system, there was a linear relationship between polymer layer thickness and monomer conversion or molecular weight of "free" polymers. The thickness of the polymer brush films was greater than 80 nm after 6 h of reaction time. The grafting density was estimated to be 0.40 chains/nm(2). The "living" chain ends of grafted polymers were still active and initiated the growth of a second block of polymer. Block copolymer brushes with different block sequences were successfully prepared. The experimental surface chemical compositions as measured by X-ray photoelectron spectroscopy agreed very well with their theoretical values. Water contact angle measurements further confirmed the successful grafting of polymers from nickel and copper surfaces. The surface morphologies of all samples were studied by atomic force microscopy. This study provided a novel approach to prepare stable functional polymer coatings on reactive metal surfaces.
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