Single molecule spectroscopy reveals heterogeneous transport mechanisms for molecular ions in a polyelectrolyte polymer brush

Carmen Reznik, Nicel Estillore, Rigoberto C. Advincula, Christy F. Landes

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27 Citations (Scopus)

Abstract

Single molecule polarization and fluorescence correlation spectroscopy were used to evaluate heterogeneous transport mechanisms of molecular ions within supported polyelectrolyte brushes. Modes of diffusive transport include periods of significantly restricted rotational motion, often maintained over tens of milliseconds; periods of fast molecular rotation; and occasional adsorption of fluorescent probe molecules in the brush. The studies reveal rapid switching between orientational states during each observed mode of motion. Through quantitative analysis of state occupation times, the rate constants for transitions from weakly associated to strongly associated states were extracted. Additionally, the pH dependence of the ion transport rates in the brush exhibits an abrupt, rather than continuous, trend. These single molecule studies demonstrate the presence of dynamic anisotropic interactions between the charged molecular probe and the polymer brush and provide experimental evidence of stimuli responsive switchable transport functionality in the polyelectrolyte brush.

Original languageEnglish
Pages (from-to)14611-14618
Number of pages8
JournalJournal of Physical Chemistry B
Volume113
Issue number44
DOIs
Publication statusPublished - 2009 May 11
Externally publishedYes

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ASJC Scopus subject areas

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

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