8th Liquid Matter Conference September 6-10, 2011 Wien, Austria ...

P5.14Wed 711:10-14:00Inverse patchy colloids: from microscopic description tomesoscopic coarse-grainingEmanuela Bianchi, 1 Gerhard Kahl, 1 and Christos N. Likos 21 Techinsche Universitaet Wien, Wiedner Hauptstrasse 8-10, Room DBO10A24 1040,Wien, Austria2 University of Vienna, Wien, AustriaTypically, patchy systems are characterized by the formation of a small number of directional,possibly selective, bonds due to the presence of attractive regions on the surface of otherwiserepulsive particles [1, 2]. We consider a new type of particles with patterned surfaces and werefer to them as inverse patchy colloids because, in this case, the patches on the repulsive particlesrepel each other instead of attracting. Further, these patches attract the parts of the colloid thatare free of patches. Specifically, we consider heterogeneously charged colloids consisting ofnegative spherical particles carrying a small number of positive patches. Our motivation resides ina recently presented colloidal system made of negatively charged colloids onto which positivelycharged polyelectrolyte stars are adsorbed [3]. Making use of the Debye-Hückel theory, we derivethe effective interaction potential between a pair of inverse patchy colloids with two patches onopposite poles [4]. We then design a simple coarse-grained model with the goal of dealing witha more feasible pair potential description [4]. The coarse-grained model can take advantage of amapping with the available analytical description at the microscopic level, strengthening therebythe link with the physical system. The mesoscopic model quantitatively reproduces the features ofits microscopic counterpart, while at the same time being characterized by a much higher degreeof computational simplicity. Moreover, the mesoscopic model is generalizable to an arbitrarynumber of patches.[1] A. B. Pawar and I. Kretzschmar, Macromol. Rapid. Commun. 31, 150 (2010).[2] E. Bianchi, R. Blaak and C. N. Likos, Phys. Chem. Chem. Phys. 13, 6397 (2011).[3] C. N. Likos, R. Blaak, and A. Wynveen, J. Phys. : Condens. Matter 20, 494221 (2008).[4] E. Bianchi, G. Kahl and C. N. Likos, submitted (2011).14