8th Liquid Matter Conference September 6-10, 2011 Wien, Austria ...

P7.80Thu 811:10-14:00Confined diffusion in periodic porous nanostructuresArash Nikoubashman, 1 Riccardo Raccis, 1 Markus Retsch, 2 Ulrich Jonas, 3 KaloianKoynov, 3 Hans-Jürgen Butt, 2 Christos Likos, 4 and George Fytas 21 Vienna University of Technology, Institute of Theoretical Physics and CMS, WiednerHauptstrasse 8-10 1040, Vienna, Austria2 Max Planck Institute for Polymer Research, Mainz, Germany3 FORTH, Heraklion, Greece4 University of Vienna, Vienna, AustriaWe perform fluorescence correlation spectroscopy measurements to assess the long-time self diffusionof a variety of spherical tracer particles in periodic porous nanostructures. Inverse opalstructures with variable cavity sizes and openings in the nanometer domain were employed asmodel system. We obtain both the exponent of the scaling relation between meansquare displacementand time, and the slowdown factors due to the periodic confinement for a number of particlesizes and confining characteristics. In addition, we perform Brownian Dynamics simulations tomodel and mimic the experimental conditions. Good agreement between experimental and simulationresults has been obtained regarding the slowdown factor. Fickian diffusion is predicted andseen in almost all experimental systems, while apparent non-Fickian exponents that show up fortwo strongly confined systems are attributed to polydispersity of the cavity openings. The utilityof confining periodic porous nanostructures holds promise towards understanding of constraineddiffusion with a wide range of applications ranging from water purification [1] and drug delivery[2] to tissue engineering [3].[1] E. A. Jackson and M. A. Hillmyer, ACS Nano, 4, 3548-3553 (2010).[2] S. Y. Yang et al., ACS Nano, 4, 3817-3822 (2010).[3] Z. Shao and S. Haile, Nature, 431, 170-173 (2004).The corresponding article has been submitted to ACS Nano on February 24th 2011.80