Monomer volume fraction profiles in pH responsive planar polyelectrolyte brushes |
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| Authors: | J P Mahalik Yubo Yang Chaitra Deodhar John F Ankner Bradley S Lokitz S Michael Kilbey II Bobby G Sumpter Rajeev Kumar |
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| Institution: | 1. Computer Science and Mathematics Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee;2. Center for Nanophase Materials Sciences, Oak Ridge National Laboratory, Oak Ridge, Tennessee;3. Denison University, Granville, Ohio;4. Department of Chemistry, University of Tennessee, Knoxville, Tennessee;5. Spallation Neutron Source, Oak Ridge National Laboratory, Oak Ridge, Tennessee |
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| Abstract: | Spatial dependencies of monomer volume fraction profiles of pH responsive polyelectrolyte brushes were investigated using field theories and neutron reflectivity experiments. In particular, planar polyelectrolyte brushes in good solvent were studied and direct comparisons between predictions of the theories and experimental measurements are presented. The comparisons between the theories and the experimental data reveal that solvent entropy and ion‐pairs resulting from adsorption of counterions from the added salt play key roles in affecting the monomer distribution and must be taken into account in modeling polyelectrolyte brushes. Furthermore, the utility of this physics‐based approach based on these theories for the prediction and interpretation of neutron reflectivity profiles in the context of pH responsive planar polyelectrolyte brushes such as polybasic poly(2‐(dimethylamino)ethyl methacrylate) (PDMAEMA) and polyacidic poly(methacrylic acid) (PMAA) brushes is demonstrated. The approach provides a quantitative way of estimating molecular weights of the polymers polymerized using surface‐initiated atom transfer radical polymerization. © 2016 Wiley Periodicals, Inc. J. Polym. Sci., Part B: Polym. Phys. 2016 , 54, 956–964 |
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| Keywords: | charge regulation field theory neutron reflectivity polyelectrolyte brushes |
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