Regensburg 2013 – scientific programme

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CPP: Fachverband Chemische Physik und Polymerphysik

CPP 20: Poster: Colloids and Complex Liquids

CPP 20.2: Poster

Tuesday, March 12, 2013, 18:15–20:15, Poster C

Viscosity of polyelectrolyte solutions and nanoparticle suspensions measured by AFM cantilevers — •Cagri Üzüm, Alexandra Abraham, Howard Setyamukti, Regine von Klitzing, and Sebastian Schön — Stranski-Laboratorium, Institut für Chemie, TU Berlin, Strasse des 17.Juni 124, 10623 Berlin, Germany

Density and viscosity of fluids can be determined locally i.e. in micro-scale using the frequency response of atomic force microscopy (AFM) cantilevers [1]. This contribution aims to measure the viscosity of polyelectrolyte solutions and nanoparticle suspensions at interfaces and at various volume scales. The interfacial viscosity can be manipulated by modifying the surface of the AFM cantilever (charge, hydrophobicity, etc.). The volume of interest can be controlled by tuning the resonance amplitude of the cantilevers via magnetic excitation [2]. In general, the viscosity of flexible polyelectrolyte (NaPSS, PAMPS) or small (9nm) particle systems measured by AFM increases with resonance amplitude and approaches the bulk viscosity. On the contrary, rigid polyelectrolyte (DNA, Chitin) or larger particle (26nm) systems have a significantly reduced micro-scale viscosity as compared to bulk. The entropic and kinetic sources of this difference will be addressed.

[1] Boskovic, S. et al. J. Rheol., 2002, 46, 891-899

[2] McLoughlin, N. et al. Appl. Phys. Lett., 2006, 89