Mark A. Horsch, Department of Chemical Engineering, University of Michigan, 2300 Hayward Street, Ann Arbor, MI 48109-2136 and Sharon C. Glotzer, Dept. of Chemical Engineering, University of Michigan, 2300 Hayward Street, Ann Arbor, MI 48109-2136.
Self-assembly is increasingly viewed as a means to arrange nanoscale building blocks into complex structures that may have applications in electronics, data storage, and energy utilization. Large aspect ratio nanobuilding blocks, e.g. nanorods, are of particular interest. We report results from molecular simulations of rod-like nanoparticles with a single polymer attached equidistant from each of the rod ends to create a "shape amphiphile" [1]. Previously, we reported results of a simulation study of end-tethered nanorods, which self-assemble into novel chiral cylinders, perforated lamellae, and other structures [2]. Our simulations predict that side-tethered nanorods self-assemble into very different structures including long micelles, ribbon-like "staircases", and bilayers with either nematic or smectic ordering within the bilayer depending on volume fraction. We demonstrate that the width of the micelles and the staircase structures can be varied by tuning the interactions between the nanorods and the polymer or by altering the molecular weight of the polymer. In contrast to mesostructures formed from end-tethered nanorods in which the rods pack perpendicular to the micelle or cylindrical axis, we find that side-tethered nanorods pack parallel to the micelle and ribbon axes.
[1] Horsch, M.A. and Glotzer, S.C. (preprint 2006) [2] Horsch, M.A., Zhang Z.L., and Glotzer, S.C. Self-Assembly of Polymer-Tethered Nanorods, PRL 95, (2005)