Date: Wednesday, June 27th, 2018, 15:00-16:00
Place: Material Solution Center (MaSC), Seminar room (1st floor),
Tohoku University

Lecturer: Dr. Gregor Trefalt (University of Geneva, Switzerland)
Title: “Forces in the Presence of Highly Charged Coions: From Multivalent Coions to Polyelectrolytes”

Abstract: Forces between charged surfaces in the presence of multivalent counterions were extensively studied, however much less attention was focused on systems with multivalent coions. We study the interactions between negatively charged particles with the colloidal probe technique which is based on atomic force microscope. In my talk I will present our recent work, where we explore the influence of multivalent coions on the force profiles. These ions have the same sign of the charge as the surface and they induce non-exponential double-layer force profiles. When the multivalent coions are replaced with like charged polyelectrolytes the effect on double-layer forces is even more dramatic. At higher concentrations of polyelectrolytes and larger distances oscillatory structural forces are observed. In these systems the double-layer forces and structural forces are connected through the phase shift of the structural force.