Regensburg 2013 – wissenschaftliches Programm
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CPP: Fachverband Chemische Physik und Polymerphysik
CPP 22: Focus: Wetting on smooth and rough surfaces: From spreading to superhydrophobicity I
CPP 22.2: Vortrag
Mittwoch, 13. März 2013, 10:00–10:15, H34
How soft viscoelastic surfaces control the time scales of drop spreading — Longquan Chen1, •Elmar Bonaccurso1, and Martin Shanahan2 — 1Center of Smart Interfaces, Technische Universität Darmstadt, Petersenstr. 17, 64287 Darmstadt, Germany — 2Univ. Bordeaux, I2M, UMR 5295, F-33400 Talence, France
It is known that liquid droplets spreading on a soft, viscoelastic substrate can be slowed down considerably by the formation of a wetting ridge, or protrusion of the substrate near the triple phase contact line (TPCL) due to capillary forces. Viscoelastic dissipation in the substrate can prevail over viscous dissipation in the liquid and dominate the spreading process. In this contribution we show how the internal time scales of the viscoelastic solid interact with a spreding droplet.
After contact of a droplet and a viscoelastic substrate a short, rapid spreading stage occurs. The necessary balance determining speed of motion of the TPCL is initially between capillary and inertial forces. As spreading proceeds, inertia lessens while the lower spreading speed allows for viscoelastic effects to emerge. We study the transition between inertial and viscoelastic regime by high-speed video microscopy and propose a simple model for relating the transition time with properties of the liquid and the viscoelastic substrate.