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Ultrathin gradient films using thiol-ene polymerizations

Authors

  • Vaibhav S. Khire,

    1. Department of Chemical and Biological Engineering, University of Colorado at Boulder, Boulder, Colorado 80309-0424
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  • Danielle S. W. Benoit,

    1. Department of Chemical and Biological Engineering, University of Colorado at Boulder, Boulder, Colorado 80309-0424
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  • Kristi S. Anseth,

    1. Department of Chemical and Biological Engineering, University of Colorado at Boulder, Boulder, Colorado 80309-0424
    2. Howard Hughes Medical Institute, University of Colorado, Boulder, Colorado 80309-0424
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  • Christopher N. Bowman

    Corresponding author
    1. Department of Chemical and Biological Engineering, University of Colorado at Boulder, Boulder, Colorado 80309-0424
    2. Department of Restorative Dentistry, University of Colorado Health Sciences Center, Denver, Colorado 80045-0508
    • Department of Chemical and Biological Engineering, University of Colorado at Boulder, Boulder, Colorado 80309-0424
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Abstract

The application of surface-attached, thiol-ene polymer films for controlling material properties in a gradient fashion across a surface was investigated. Thiol-ene films were attached to the surface by first depositing a thiol-terminated self-assembled monolayer and performing a thiol-ene photopolymerization reaction on the surface. Property gradients were created either by creating and modifying a gradient in the surface thiol density in the SAM or by changing the polymerization conditions or both. Film thickness was modified across the substrate by changing either the density of the anchoring thiol functional groups or by changing the reaction conditions such as exposure time. Thicker films (1–11 nm) were obtained by polymerizing acrylate polymer brushes from the surface with varying exposure time (0–60 s). The two factors, that is, the surface thiol density and the exposure time, were combined in orthogonal directions to obtain thiol-ene films with a two-dimensional thickness gradient with the maximum thickness being 4 nm. Finally, a thiol-acrylate Michael type addition reaction was used to modify the surface thiol density gradient with the cell-adhesive ligand, Arg-Gly-Asp-Ser (RGDS), which subsequently yielded a gradient in osteoblast density on the surface. © 2006 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 44: 7027–7039, 2006

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