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CPP: Chemische Physik und Polymerphysik

CPP 15: Poster: Dünne Filme, Monolagen und Oberfl
ächen

CPP 15.9: Poster

Mittwoch, 13. März 2002, 16:30–18:00, B

Confined liquids in pores with chemically patterned walls — •Anke Klingner, Thomas Becker, and Frieder Mugele — Universitaet Ulm, Abt. Angewandte Physik, Albert-Einstein-Allee 11, 89081 Ulm

Nowadays a lot of attention is paid to the guidance of small amounts of liquids by microstructures in the field of microfluidics. We are interested in the morphology and stability of liquids between the structured walls of a micrometer sized slit pore. The measurements were performed using a newly designed, modified surface forces apparatus (SFA) with 2-dimensional image acquisition. The instrument is equipped with motorized micrometer screws, which allow one to control the distance between the pore walls. The silvered pore walls were hydrophobized by 1-Dodecanethiol. Subsequently, hydrophilic patterns, e.g. stripes, of salts like MgF2 or CaF2 were evaporated. Well-defined amounts of liquid glycerol were deposited on the hydrophilic areas both by micropipetting and spin coating. The volume of hygroscopic liquids in the pore can also be tuned in situ by controlling the humidity in the chamber. The liquid in the gap between the two surfaces shows morphologies of channels and bridges spanning across the gap. The geometry of the liquid surfaces was analyzed using the measured interference fringes and a numerical simulation of the transmission through the SFA. We compare our results with theoretical predictions regarding the morphological stability and phase diagram of liquid bridges.