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Peter Megson

Thesis

Experiments on Surfactants and Thin Fluid Films

Advisor
Rachel Levy
Second Reader(s)
Jon Jacobsen

Abstract

We investigate the spatiotemporal dynamics of a surfactant monolayer on a thin fluid film spreading inward into a region devoid of surfactant, a system motivated by the alveolus of the human lung. We perform experiments that simultaneously measure the fluid height profile and the fluorescence intensity due to our fluorescent surfactant, NBD-PC. We perform experiments on both a Newtonian layer of glycerol and a shear-thinning fluid layer consisting of xanthan gum mixed with glycerol. We can very successfully extract height profiles on the xanthan gum fluid, although the simultaneous measurement of fluorescent intensity profiles proved problematic, as the laser tended to stymie the fluorescent intensity measurement. We attempt and find some success with simply measuring surfactant fluorescent intensity by itself and reconstructing behavior between the two separate measurements. We were ultimately able to make a comparative measurement of the velocity of the leading edge of surfactant on xanthan gum and glycerol.

Proposal

Surfactants on Thin Fluid Films

Additional Materials

Poster