Sonderforschungsbereich 481

Subproject A14:

Analysis of wrinkled self-assembled low-dimensional colloidal aggregates

Prof. Andreas Fery(Physikalische Chemie II)

The aim of the project is to generate patterned assemblies of colloidal particles by means of wrinkled surfaces. Patterned assemblies of colloidal particles are of interest for various tasks like controlling optical (optical bandgap materials) or electronical properties (wires), for sensing or combinatorial chemistry. Generally, periodically structured surfaces on the sub-micron scale are obtained by applying expensive lithographic processes on surfaces which go along with environmentally harmful etching steps. In this project, we use a lithography-free approach for creating such surfaces that is based on controlled wrinkling followed by a template assisted self-assembly process: We prepare substrates which are topographically structured on the micron/submicron scale. Mechanical instabilities of a stiff skin on a soft substrate create periodical wrinkled patterns with unlimited size and shape of the substrate. The topographical contrast can subsequently be exploited to direct the patterned assembly of colloidal particles by means of dip-coating. Capillary forces are used to direct the colloidal crystal assembly into the wrinkled substrates. The aim of the project is to understand the physical built-up process of such structured surfaces in detail and to investigate the optical/magnetic properties of assembled colloids.