Nonlinear osmotic brush regime: Experiments, simulations and scaling theory

Heiko Ahrens*, Stephan Förster, Christiane A. Helm, Arun Narayanan Nair, Ali Naji, Roland R. Netz, Christian Seidel

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

59 Scopus citations

Abstract

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.

Original languageEnglish (US)
Pages (from-to)16870-16876
Number of pages7
JournalJournal of Physical Chemistry B
Volume108
Issue number43
DOIs
StatePublished - Oct 28 2004

ASJC Scopus subject areas

  • Physical and Theoretical Chemistry
  • Surfaces, Coatings and Films
  • Materials Chemistry

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