Nonlinear osmotic brush regime:: Experiments, simulations and scaling theory

被引:69
作者
Ahrens, H [1 ]
Förster, S
Helm, CA
Kumar, NA
Naji, A
Netz, RR
Seidel, C
机构
[1] Ernst Moritz Arndt Univ Greifswald, Inst Phys, FL Jahn Str 16, D-17487 Greifswald, Germany
[2] Univ Hamburg, Inst Phys Chem, D-20146 Hamburg, Germany
[3] Univ Munich, Sekt Phys, D-80333 Munich, Germany
[4] Max Planck Inst Colloids & Interfaces, D-14476 Potsdam, Germany
关键词
D O I
10.1021/jp049553c
中图分类号
O64 [物理化学(理论化学)、化学物理学];
学科分类号
070304 ; 081704 ;
摘要
We experimentally and theoretically consider highly condensed planar brushes made of charged polymers. Using X-ray reflectivity on polyelectrolytes that are anchored at the water-air interface, it is shown that such strongly stretched brushes show a slight but detectable height variation upon lateral compression. This stands in contrast to the well-accepted scaling relation in the so-called osmotic brush regime, which predicts the brush height to be independent of the grafting density. Similar effects are seen in simulations on highly compressed charged brushes. Scaling arguments that go beyond the linear approximation for the entropy of confined counterions and for weak chain-stretching are able to explain those findings on a semiquantitative level.
引用
收藏
页码:16870 / 16876
页数:7
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