At the fluid-solid interface, chemical and physical interactions influence slip and flow of the fluid at the solid surface. Proposed theories state that when an ultra-smooth surface (< 5-7 nm RMS roughness) contacts a fluid, the hydrodynamic no-slip boundary condition can be violated and a complete slip boundary can be achieved. A dewetting technique provides a useful way to experimentally analyze and investigate these theories. This technique translates a solid substrate slowly through a droplet of bulk fluid which then is extruded into a thin film on the substrate's surface. Dewetting allows for the direct investigation of this fluid-solid interface via spectroscopy. This research reports behaviors of fluid thin-films supported on well-defined surfaces with RMS roughness values between 1 and 30 nm. Roughness is determined via AFM and film behavior is monitored using ellipsometry, polarization modulation-infrared reflection absorption spectroscopy (PM-IRRAS), Raman spectroscopy, et. al. The effects of fluid viscosity on film's structure and flow is also reported by analyzing mixtures of fluids such as glycerol and water. Resulting analysis of fluid films on these surfaces provides molecular level details of these interfacial boundaries which show that the complete slip boundary is generally not obtainable by controlling substrate physical geometry alone.

Interfacial analysis of fluids at the solid surface: The complete slip boundary condition

246th National Meeting (2013)

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