Starlike polymer brushes in Θ-solvent |
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Authors: | Chan-Fei Su Wei Cui Holger Merlitz Chen-Xu Wu Jens-Uwe Sommer |
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Affiliation: | 1. Department of Physics and ITPA, Xiamen University, Xiamen 361005, People''s Republic of China;2. Leibniz-Institut für Polymerforschung Dresden, 01069 Dresden, Germany |
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Abstract: | The properties of starlike polymer brushes in Θ-solvent are investigated using molecular dynamics simulations, scaling- and mean-field theory. Deviations of layer thickness and monomer density from predictions of scaling theory are analyzed and explained. Contrary to common believes, we conclude that the Alexander-deGennes scaling theory is not valid for starlike polymer brushes in Θ-solvent, unless the grafting density is extremely low. A comparison with structural and dynamical properties of starlike polymer brushes in good solvent is carried out. Previous studies in good solvent reported about the dual-population structure of these branched polymer brushes, with coexisting phases of stretched and retracted molecules; the same separation emerges in Θ-solvent, though at higher grafting densities. Molecular tension and population fractions are shown to be solvent-dependent, and a reduced dynamical flip-rate between the two populations is observed for the case of the Θ-brush. |
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Keywords: | Starlike polymer brushes MD simulation Mean-field theory |
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