Berlin 2008 – wissenschaftliches Programm
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CPP: Fachverband Chemische Physik und Polymerphysik
CPP 34: POSTERS Polymerphysics
CPP 34.56: Poster
Donnerstag, 28. Februar 2008, 17:00–19:30, Poster A
Forces of interaction between polyacrylic acid brushes as measured by optical tweezers — •Gustavo Dominguez-Espinosa1, Alla Synytska2, Astrid Drechlser2, Christof Gutsche1, Friedrich Kremer1, Petra Uhlmann2, and Manfred Stamm2 — 1Institute of Experimental Physics I, Leipzig University, Linnéstr. 5, 04103, Leipzig, Germany — 2Leibniz Institute of Polymer Research Dresden, Hohe Str. 6, 01069, Dresden, Germany
The forces of interaction between polyacrylic acid brushes grafted on two separated silica colloids are measured by Optical Tweezers (resolution of the forces 0.5 pN and resolution in position 3 nm). The interaction potential of the polyacrylic acid brushes is determined in dependence of the pH, ion concentration and valence of the surrounding medium. Scaling of the brush thickness with the power of the ionic strength is found in qualitative agreement with the theoretical predictions. The observed increase in the brush thickness with the increasing pH is attributed to the electrostatic repulsion caused by dissociation of the polyacrylic acid.