title: Assembly of nanorods into designer superstructures: the role of templating, capillary forces, adhesion, and polymer hydration.
abstract: The assembly mechanism by which hundreds of thousands of two-segment gold-polypyrrole nanorods are assembled into kinetically controlled shape-directed superstructures is examined to predict the range of nanoparticle sizes and materials that can be utilized in their formation. Four processes are responsible for assembly: templating, capillary force assembly, adhesion, and polymer hydration. It is shown that templating, where rods are prepositioned for assembly, is scale invariant and that the energy-minimized state after this step is highly disordered. In addition, we predict that superstructures can be made independently from patterns of rods separated by a distance as small as six times the inter-rod spacing. Both modeling and experiment show that adhesion and polymer dehydration, which induces curvature in the superstructures, are applicable to other materials. However, the high surface energy and low elastic modulus of polypyrrole are advantageous toward generating three-dimensional structures, inducing curvature at gold/polypyrrole length ratios as large as 7:1.
authors.affiliation: Department of Chemistry and International Institute of Nanotechnology, Northwestern University, Evanston, Illinois 60208, USA. jciszek@luc.edu
authors.forename: Jacob W
authors.initials: JW
authors.lastname: Ciszek
authors.forename: Ling
authors.initials: L
authors.lastname: Huang
authors.forename: Stefan
authors.initials: S
authors.lastname: Tsonchev
authors.forename: Yuhuang
authors.initials: Y
authors.lastname: Wang
authors.forename: Kenneth R
authors.initials: KR
authors.lastname: Shull
authors.forename: Mark A
authors.initials: MA
authors.lastname: Ratner
authors.forename: George C
authors.initials: GC
authors.lastname: Schatz
authors.forename: Chad A
authors.initials: CA
authors.lastname: Mirkin
mesh_terms: D000537:Aluminum Oxide / Q000737:chemistry; D006046:Gold / Q000737:chemistry; D053758:Nanoparticles / Q000737:chemistry; D043942:Nanotubes / Q000737:chemistry*; D011108:Polymers / Q000737:chemistry*; D011758:Pyrroles / Q000737:chemistry; D014867:Water / Q000737:chemistry*
chemical_list: D011108:Polymers; D011758:Pyrroles; D014867:Water; C067635:polypyrrole; D006046:Gold; D000537:Aluminum Oxide