(80c) Simulation of the Hydrodynamically-Assisted Self-Assembly of DNA-Functionalized Colloidal Particles in 2d

The production of extremely small structures, beneath the limits of modern-day lithographic techniques, is an area of intense interest these days. Self-Assembly or ?bottom up? methods of manufacture are being explored as an alternative means for forming nanoscopic structures as opposed to ?top down? direct patterning methodologies. Of particular interest is the self-assembly of nanometer to micron sized particles from a bulk solution into an adsorbed monolayer. The formed monolayers have a wide range of potential applications. Ordered patterns of nanoparticles could be used directly, for example, as high-density magnetic media, if the particle were ferromagnetic, or indirectly as templating agents. Other potential applications for these ordered arrays include photonic devices and meta-materials. Typically the background thermal motion is used as a means to sample configuration space during the self-assembly process. This method, however, limits the strength of the interparticle interactions as they must be on the order of kT for efficient sampling. We are using simulations to understand how an external forcing that is greater than kT can be used as a replacement for thermal sampling. Specifically, we are looking at the role of hydrodynamics in aiding the self-assembly process. We study computationally the effects of an in-plane linear shear stress on the self-organization of a binary system of ssDNA-functionalized colloidal particles in 2D through dynamic simulation. By varying the stoichiometry and magnitude of the shear stress it is possible to favor the formation of either the AB lattice or the AB2 lattice. Simulations performed without shear stress show little formation of structure, while the addition of shear leads to increased formation of these lattices. These simulations show that hydrodynamics offers an effective alternative to thermal motion as a means for sampling configurational space during the self-assembly process.