Berlin 2015 – wissenschaftliches Programm
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CPP: Fachverband Chemische Physik und Polymerphysik
CPP 15: P1: Interfaces and Thin Films
CPP 15.13: Poster
Montag, 16. März 2015, 16:00–19:00, Poster A
Influence of the chemical structure on the slip boundary condition of liquids — •Mischa Klos1, Sebastian Backes1, Juan Manuel Castillo Sanchez2, Hans Hasse2, and Karin Jacobs2 — 1Saarland University, Experimental Physics, D-66123 Saarbrücken — 2TU Kaiserslautern, Laboratory of Engineering Thermodynamics, D-67663 Kaiserslautern
On small scales, especially in microfluidic devices, the role of the solid/liquid interface gets more important for the flow dynamics. Our experiments probe slippage via the dewetting of thin polymer films on hydrophobic substrates [1]. As hydrophobic coatings we use amorphous polymers (AF1600, AF2400) and different types of highly ordered self-assembled silane monolayers on top of silicon substrates. On silane surfaces, polystyrene (PS) of low molecular weight exhibit slip lengths up to micrometers [2]. On AF1600, no significant slip is observed . Scattering studies reveal an ordering of the PS side chains at the solid/liquid interface depending on the structure of the substrate [3]. Recent simulations were able to characterize the used SAMs[4]. However, the situation changes if PMMA or polyvinylpyridine (PVP) are used: Dewetting experiments show that slip is less pronounced in PVP and in PMMA films. Obviously, the structure of the side groups play a significant role. X-ray reflectometry supplement this hypothesis and give further insight to the slippage mechanism at the solid/liquid interface. [1] O. Bäumchen, et.al., J Phys Condens Mat 24 (2012) 325102 [2] R. Fetzer, et. al, Europhys Lett 75 (2006) 638 [3] P. Gutfreund, et. al.,Phys Rev E 87 (2013) 012306 [4] J.M. Sanchez, et. al. submitted