Berlin 2018 – wissenschaftliches Programm
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CPP: Fachverband Chemische Physik und Polymerphysik
CPP 79: Wetting, Microfluidics and Confined Liquids II
CPP 79.4: Vortrag
Freitag, 16. März 2018, 10:15–10:30, PC 203
Influence of the ordering of depletants on structural forces in thin liquid films — •Michael Ludwig1, Sebastian Schön2, and Regine von Klitzing1 — 1Technische Universität Darmstadt — 2Technische Universität Berlin
Structural forces are observed when pure solvents and ionic liquids, as well as dispersions containing nanoparticles, micelles, polymers or polyelectrolytes are confined between two smooth surfaces. Upon surface-approach, liquid matter has to be depleted from the vicinity of the surfaces, altering the interactions between the surfaces.
Recent experimental studies reveal the superposition of structural forces with DLVO-type forces [1,2]. Here, we will focus on nanoparticle dispersions in confinement between two charged silica-surfaces, as probed in our experiments using a colloidal-probe atomic force microscope (CP-AFM). An additional repulsive term has to be introduced to accurately fit experimental data. This additional term will be discussed in terms of the DLVO-framework.
At high concentrations of depletants, structural force profiles appear to show oscillatory behaviour. The corresponding wavelength λ correlates with the mean particle distance of the depleting particles in the bulk liquid [3]. Different dependencies between wavelength λ and particle number density ρ will be presented considering the bulk liquid geometries.
[1] S. Perkin et al., Phys. Rev. Lett. 119, 026002 (2017) [2] G. Trefalt et al., Phys. Rev. Lett. 177, 088001 (2016) [3] R. von Klitzing et al., Soft Matter 7, 10899 (2011)