Coverage Dependent Evolution of Two-Dimensional Dendrimer/Mica Domain Patterns
F.T. Xu#, S.C. Street+, and J.A. Barnard#*
#Department of Materials Science and Engineering
University of Pittsburgh, Pittsburgh, PA 15261
and +Center for Materials for Information Technology
The University of Alabama, Tuscaloosa, AL 35487-0209
We have recently extended our MRSEC-enabled interdisciplinary (materials engineering/chemistry) work on pattern formation in aerosol-deposited dendrimer films to include fabrication of stable, two-dimensional (2D), two-phase domain patterns which result from competing short-range attractive and long-range repulsive interactions. The domain length scale in these systems can be controlled by engineering the relative strength of the competing interactions. The opportunity to vary this length and thus pattern formation at the nanoscale over large areas has exciting technological implications. For a two-phase A-B system the evolution of domain patterns as a function of the area fraction, f = fA = 1 – fB, is predicted to follow the sequence: circular islands of A in a matrix of B (the droplet phase) → alternating elongated domains of A and B (the striped phase) → and circular islands of B in a matrix of A (the inverted droplet phase), as f is varied from 0 to 1. We have confirmed this basic prediction very recently and for the first time in a new materials system: dendrimer molecules adsorbed onto the surface of mica (see Figure 1).