Theory of nanoparticle self-assembly at oil/water interfaces: The role of curvature

COLL 372

Steven O. Nielsen, steven.nielsen@utdallas.edu1, Preston B. Moore, p.moore@usip.edu2, Wataru Shinoda, w.shinoda@aist.go.jp3, Robert JB. Kalescky, robert.kalescky@student.utdallas.edu4, and Chi-cheng Chiu, cxc058300@utdallas.edu1. (1) Department of Chemistry, The University of Texas at Dallas, 2601 North Floyd Road, Richardson, TX 75083-0688, (2) Department of Chemistry & Biochemistry and West Center for Computational Chemistry and Drug Design, University of the Sciences in Philadelphia, 600 South 43rd Street, Philadelphia, PA 19104, (3) Research Institute for Computational Sciences, National Institute of Advanced Industrial Science and Technology, Central 2, 1-1-1 Umezono, Tsukuba, 305-0035, Japan, (4) Department of Chemistry, University of Texas at Dallas, 2601 North Floyd Road, Richardson, TX 75080
Oil/water interfaces provide a powerful means of directing the self-assembly of nanoparticles (NPs) into ordered nanostructures. However, current interpretation of these systems in the experimental literature is based on macroscopic concepts that do not apply at the nanoscale. Here we provide a proper framework, based on theory and computer simulations, with which to interpret data. Firstly, we discuss the NP radius dependence of the oil/NP and water/NP surface tensions, and present a method to calculate them. Secondly, we measure the three-phase line tension and discuss its impact on the attachment of NPs to the oil/water interface. We compute the free energy profile of NPs as a function of their distance from the oil/water interface, and compare the optimal location to that predicted by the macroscopic model (Pieranski, Phys. Rev. Lett. 45, 569 (1980)). These results may change the interpretation of the experimental observation that large NPs displace small NPs from the oil/water interface.
 

Polymer-Nanoparticle Systems: Theory, Simulation, Experiments
9:00 AM-12:00 PM, Wednesday, April 9, 2008 Morial Convention Center -- Rm. 227, Oral

Division of Colloid & Surface Chemistry

The 235th ACS National Meeting, New Orleans, LA, April 6-10, 2008