Inverse patchy colloids: effect of the interplay between attractive and repulsive anisotropic interactions on the collective behaviours

by Emanuela Bianchi (University of Wien)

Friday 9 Nov 2012, 11:00 → 13:00 Europe/Rome

Aula Corbino (Dip. di Fisica - Edificio E. Fermi)

Over the past decade, the already vast possibilities offered by colloidal particles as building blocks for new materials have been substantially widened by the advent of patchy colloids, i.e., colloidal particles with chemically or physically patterned surfaces. By virtue of the well-defined bonding geometries, patchy particles are nowadays regarded as ideal units of novel self-assembled materials with specific symmetries and physical properties. We have recently introduced a new class of patchy particles, which w! e refer to as inverse patchy colloids (IPCs). While patchy systems are typically characterized by the presence of attractive regions on the surface of otherwise repulsive particles, IPCs are mutually repulsive particles carrying extended patches that repel each other and attract those parts of the colloid that are free of patches. Examples of IPCs are colloidal particles with a heterogeneous surface charge distribution. We have developed a suitable description of such systems starting from first principles in order to keep a connection with the microscopic systems. The main feature of IPC systems is not anymore the limited valence in bonding, but rather a competitive interplay between attractive and repulsive anisotropic interactions. The role of such an interplay as well as the effect of the patch extension have been studied with respect to collective phenomena such as crystal formation, dynamical arrest or the gas-liquid phase separation. The investigation of a wide s! election of IPC systems in the bulk as well as in a confined g! eometry, together with the study of the two-dimensional counterparts of such systems, gave evidence of very promising self-assembly scenarios, such as planar and even ordered porous structures.