Wednesday, November 7, 2007 - 4:04 PM

Local Ordering Of Tethered Nanospheres And Nanorods And The Stabilization Of The Gyroid Phase

Christopher R. Iacovella1, Mark A. Horsch2, Aaron S. Keys1, Zhenli Zhang2, and Sharon C. Glotzer2. (1) Department of Chemical Engineering, University of Michigan, 2300 Hayward Street, Ann Arbor, MI 48109-2136, (2) Dept. of Chemical Engineering, University of Michigan, 2300 Hayward Street, Ann Arbor, MI 48109-2136

The use of polymer tethered nanoparticles provides a unique method to control the self-assembly of nanoparticles into ordered mesophases that resemble the complex morphologies of block copolymers. However, due to the geometry of the nanoparticles, these tethered systems are able to adopt complex local order not normally found in block copolymer systems. For example, in the double gyroid phase nanospheres are found to form icosahedral arrangements [1] where as nanorods are found to form liquid-crystalline, twisted-hexagonal arrangements [2]. We carry out Brownian dynamics simulations of self-assembly of tethered nanospheres and tethered nanorods and characterize the local geometry of nanoparticle packings.  We show a connection between the stability of the double gyroid phase and the local order adopted by polymer tethered nanospheres and nanorods [3].

[1] C.R. Iacovella, A.S. Keys, M.A. Horsch, S.C. Glotzer "Icosahedral packing of polymer-tethered nanospheres and stabilization of the gyroid phase" Phys. Rev. E 75, 040801(R) (2007)

[2] M.A. Horsch, Z.L. Zhang and S.C. Glotzer, "Simulation studies of self-assembly of end-tethered nanorods in solution and role of rod aspect ratio and tether length," J. Chem. Phys., 125 (18): Art. No. 184903 NOV 14 (2006)

[3] C.R. Iacovella, M.A. Horsch, A.S. Keys, Z.L. Zhang, and S.C. Glotzer, preprint.