Dresden 2011 – wissenschaftliches Programm
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CPP: Fachverband Chemische Physik und Polymerphysik
CPP 38: Poster: Colloids and Complex Liquids
CPP 38.6: Poster
Mittwoch, 16. März 2011, 17:00–19:00, P2
Forces of Interaction within Single Pairs of Polymer-grafted Colloids as Measured by Optical Tweezers — •Mahdy M. Elmahdy1,3, Alla Synytska2, Christof Gutsche1, Gustavo Dominguez-Espinosa1, Astrid Drechsler2, Petra Uhlmann2, Manfred Stamm2, and Friedrich Kremer1 — 1Institute of Experimental Physics I, Leipzig University, Linnéstrasse 5, 04103, Leipzig, Germany — 2Leibniz Institute of Polymer Research Dresden, Hohe Str. 6, 01069 Dresden, Germany — 3Department of Physics, Mansoura University, Mansoura 35516, Egypt
Optical Tweezers are ideal tools to measure the interaction forces between polyelectrolyte-grafted colloids. Using this technique, the forces of interaction within single pairs of poly(acrylic acid) (PAA) and poly(2-vinylpyridine) (P2VP)-grafted colloids are measured as a function of concentration, valency as well as pH of the surrounding medium [1,2]. The PAA- and P2VP-grafted colloids data are quantitatively described by the Jusufi model for spherical polyelectrolyte brushes. The transition from an osmotic to the salted brush regime is observed in both polyelectrolytes. In the salted brush regime, power law dependence with an exponent of 0.3 is found, in good agreement with scaling laws. For the PAA-grafted colloids, the brush height increases with increasing pH while the P2VP-grafted colloids show a transformation in the conformation of the brushes.
References [1] Elmahdy et al., Macromolecules 2009, 42, 9096. [2] Dominguez et al., Polymer 2008, 49, 4802.