Salzberg Chemistry Seminar: Ilona Kretzschmar
Mon, Feb 25
12:00 PM — 1:00 PM
MR160 Convent Avenue
Ilona Kretszchmar, CCNY Dept of Chem Engineering: "Patchy Particles – Why does asymmetry matter?"Abstract
Anisotropically surface modified particles, so-called patchy particles, have been recognized as important building blocks in the directed assembly of particles into desired target structures. Recent simulation work by Francesco Sciortino has shown that such asymmetric patches are able to decide, which of two crystal structures, i.e., cubic tetra stack vs. face-centered cubic (energetically equal with spherical patches), will form from a patchy particle colloidal suspension owing to the fact that the patch asymmetry completely prohibits one or the other crystal structure. Two things are urgently needed for experimentalists to test these simulation predictions. On one hand, researchers need to be able to produce large volumes of patchy particles with identical patches such that their crystallization behavior can be studied. On the other hand, the method has to enable the changing of patch shape in a very accurate and continuous fashion.
In this talk, we will report on the preparation of patchy particles using a combination of a rotatable template and the glancing angle vapor deposition (GLAD) developed in our group. Simple geometrical models are used to predict the patch geometry and relative orientation of the patches and confirmed by scanning electron microcopy imaging. We will further report on the use of patch geometry, material, and position for the pre-programmed, field-directed assembly of such patchy particles in electric and magnetic fields and the potential application of these patchy particles in the assembly of new materials and rheological applications.
 F. Romano and F. Sciortino Nature Comm. 2012, 3, 975.