Monday, June 16, 2008
Room 1 (McKimmon Conference Center)
233

Electrically-Driven Alignment of Unique Anisotropic Polymer Particles

Kevin P. Herlihy, Janine Nunes, and Joseph M. DeSimone. University of North Carolina at Chapel Hill, Chapel Hill, NC

The assembly of colloidal particles has long been a rich and continuously growing area of materials science, with great potential in numerous applications including electronics, optics and biotechnology. Within this field however, limited research has been published on the assembly of highly anisotropic polymer particles, with the bulk of that work devoted mainly to rod and disk polymer particle shapes. This may in part be due to a lack of effective fabrication processes for the preparation of anisotropic polymer particles with the monodispersity and range of compositions required for in-depth study. The soft lithography technique, Particle Replication in Non-wetting Templates (PRINT), allows for the fabrication of nondisperse nanometer and micron-sized particles of varying size, shape and composition. This technique is ideally suited to the synthesis of anisotropic particles with novel shapes, and as such, the colloidal assemblies generated by such particles can be straightforwardly investigated. Utilizing the PRINT process, a range of unique, highly anisotropic polymer particles have been synthesized, including rods, disks, hexnuts and boomerangs. Here we present on the use of dielectrophoresis, a technique well-known to drive the assembly of colloidal systems, to organize these particles. Particle alignment and particle chaining were observed in aqueous suspensions using moderate electric fields and frequencies (20-40 V AC, 0.5 – 5.0 kHz). Furthermore, particle alignment was performed in the monomer, N-vinyl-2-pyrrolidinone, which was polymerized resulting in aligned polymer composites.