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

Thu 811:10-14:00P7.1Dissipative particle dynamics simulation for surfactantsolution confined to nanochannel with striped JanussurfacesNoriyoshi Arai, 1 Kenji Yasuoka, 2 and Xiao Cheng Zeng 31 University of Electro-Communications, 1-5-1, Chofugaoka 182-8585, Chofu,Japan2 Keio Univeristy, Yokohama, Japan3 University of Nebraska-Lincoln, Lincoln, USARecent developments in nanofluidics and nanofabrication have provided promising opportunitiesfor the control of fluid motion through nanodevices with features less than 100 nm in one twodirections. On one hand, such developments are driven by the efforts to replace the polymer gelswith solid-state materials that can be engineered to entail nanoscale structures for applications suchas DNA separation. On the other hand, they are prompted by the curiosity-driven research for theexploration of new phenomena stemming from interactions between the fluid and the surface of thenanofluidic system, for example, the surface with tailor-made nanoscale patterns. Indeed, growingattention has been devoted to the prediction of new phenomena at length scales significantlybelow those characterizing known mechanical phenomena in bulk fluids. Herein, we present acomputer simulation study of static and shear-flow properties of a surfactant solution confined toa nanochannel whose inner surface possesses periodic and hybrid hydrophobic and hydrophilicpatterns (i. e. the stripe-patterned Janus surface). It is known that in Newtonian bulk fluids, theshear viscosity does not depend on the applied shear rate, whereas in non-Newtonian fluids it does.Most non-Newtonian fluids shear thin, i. e. , their shear viscosity decreases upon faster shearing.When fluids are confined to nanoscale channels, the shear viscosity and morphology of fluids canbe significantly affected by chemical conditions of the confining surfaces, and under such conditions,the connection between the shear-thinning (or shear-thickening) and morphology transitionat nanoscopic scale are still largely unexplored. We find that rich phase behavior of the surfactantsolution can emerge within the nanochannel at different chemical conditions. More importantly,we find that the shear-flow dynamics of the surfactant can be significantly regulated under differentshear rate exerted by the Janus surface.1