(149g) Nanowires, Spheroids, Dispersions: the Self-Assembly of Colloidal Nanoparticles

Low-dimensional nanostructures are ideal building blocks for nano-structured materials. We are interested in nanowires, e.g. one-dimensional structures that function as nano-scale interconnects while retaining radial quantum confinement. Solid nanowires can be prepared by several non-lithography methods. Colloidal nanowires that can be synthesized in complex mixtures by exploiting dipole-dipole interactions [1]. By conducting Monte Carlo simulations in the canonical ensemble we show here that colloidal nanowires can be obtained simply by manipulating the effective interactions between the colloidal nanoparticles. In our minimal model we describe colloidal particles as square-well spheres. Mimicking experimental results [2], we induce directional interactions by growing polymers along one main circumference of the colloids. We show here that by tuning interaction parameters including square-well depth and width, and polymers density and length, it is possible to promote the assembly of the colloidal particles yielding nanowires, spherical aggregates, or uniform dispersions. Based on our results, we argue that when temperature-responsive polymers are employed [3] small changes in system temperature can promote the formation of different nanostructures, thus allowing us to control the macroscopic properties in adaptive colloidal systems (e.g. viscosity, transparency, conductance).

1. B. Ozturk, I. Talukdar, B. Flanders, The directed assembly of CdS interconnects between targeted points in a circuit, Appl. Phys. Lett. 86 (2005) 183105.

2. Y.-S. Cho, G.-R. Yi, J.-M. Lim, S.-H. Kim, V.N. Manoharan, D.J. Pine, S.-M. Yang, Self organization of bidisperse colloids in water droplets, J. Am. Chem. Soc. 127 (2005) 15968.

3. Y. Lu, G.L. Liu, L.P. Lee, High-density silver nanoparticle film with temperature-controllable interparticle spacing for a tunable surface enhanced Raman scattering substrate, Nano Letters, 5 (2005) 5.