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E. Bianchi:
"Heterogeneously charged colloids: from modeling to self-organization";
Vortrag: NanoTrans Annual Meeting 2017, Berlin; 27.02.2017 - 03.03.2017.

We consider heterogeneously charged colloids consisting of negatively charged spherical particles carrying a small number of positively charged patches. Making use of the Debye-Hückel theory, we derive the effective interaction potential between a pair of inverse patchy colloids with two patches on opposite poles. We then design a simple coarse-grained model via a mapping with the analytical pair potential, which is characterized by a much higher degree of computational simplicity. Subsequently, we consider the self-assembly of such inverse patchy colloids in confined geometries on changing the patch size and the overall charge of the colloids and, possibly, of the confining walls. Depending on the charges of the underlying substrate and of the particles, a rich and versatile assembly scenario takes place, resulting from the complex interplay between directional attractive and repulsive particle− particle and particle− substrate interactions. Upon subtle variations of the relative charge of the system components, emerging via pH modification, reversible changes either from extended aggregates to a monomeric phase or from triangular to square domains are observed. Relaxing the confinement and allowing for the formation of three-dimensional structures, we observe the formation of gel networks, self-assembled layered phases or close-packed crystals, that reflect the trends observed in the corresponding quasi two-dimensional systems.

Projektleitung Gerhard Kahl:
DFS