Direct measurement of depletion and hydrodynamic forces in solutions of a reversible supramolecular polymer

W. Knoben, N.A.M. Besseling, M.A. Cohen Stuart

    Research output: Contribution to journalArticleAcademicpeer-review

    20 Citations (Scopus)

    Abstract

    In this paper, the investigation of surface forces in semidilute solutions of a nonadsorbing hydrogen-bonded reversible supramolecular polymer is described. Colloidal probe atomic force microscopy was used for direct measurement of depletion forces. Hydrodynamic drag on the AFM cantilever with the colloidal probe was measured both far away from and close to the planar substrate surface. The results indicate that the presence of the depletion layer causes slip at the surfaces with a large apparent slip length. Our analysis explains how the presence of slip enables the measurement of (relatively weak) depletion forces in solutions with a high viscosity by significantly reducing the hydrodynamic forces. The range and magnitude of the measured depletion forces are qualitatively in agreement with previous experiments and theoretical predictions. Due to the relatively large experimental error, no quantitative conclusions can be drawn. Depletion-induced phase separation of suspensions of stearylated silica particles was also observed. Phase separation becomes more pronounced with increasing polymer concentration. --------------------------------------------------------------------------------
    Original languageEnglish
    Pages (from-to)6095-6105
    JournalLangmuir
    Volume23
    Issue number11
    DOIs
    Publication statusPublished - 2007

    Keywords

    • equilibrium polymers
    • chain stoppers
    • surface forces
    • particles
    • dispersions
    • microscope
    • stability
    • thermodynamics
    • suspensions
    • dynamics

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