کد مقاله | کد نشریه | سال انتشار | مقاله انگلیسی | نسخه تمام متن |
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5181116 | 1380953 | 2014 | 13 صفحه PDF | دانلود رایگان |

Langevin dynamics simulations are performed to study polyelectrolyte brushes by varying the chain grafting density Ïg, the added salt valence Z, and concentration Cs. The brush thickness H follows a scaling relation in monovalent salt solutions as Csâ0.15, decreasing more slowly than the scaling prediction. In divalent and trivalent salt solutions, H acquires a minimum value at the stoichiometric point, and then levels off and slightly increases, respectively. The shape and orientation of the chains change with Cs accordingly. An electric double layer is formed around the brush rim, revealed by the calculation of vertical charge distribution. Increasing Ïg, Z, Cs reduces the width of the layer. Side-view density study further shows how the three parameters transform the brush profile from an individual-chain distribution to a homogeneous one. Finally, about 90% of chain charges are neutralized by the ions trapped in the brushes. It is found that ion condensation on the chains can be described by Manning's theory in sparse grafting and dilute salt conditions.
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Journal: Polymer - Volume 55, Issue 12, 6 June 2014, Pages 2900-2912