Wed February 17th 2010
HR Z109
Seminar High-viscosity droplets on anisotropic surfaces
Olesya Bliznyuk


We present experimental results on the tunable anisotropic wetting behavior of chemically patterned anisotropic surfaces. The equilibrium shape of asymmetric droplets, arising from patterns of alternating hydrophilic (pristine SiO2) and hydrophobic (fluoroalkylsilane self-assembled monolayers) stripes with dimensions in the low-micrometer range, are investigated in relation to the stripe widths. Owing to the well-defined small droplet volume, the equilibrium shape as well as the observed contact angles exhibit unique scaling behavior. Only the relative width of hydrophilic and hydrophobic stripes proves to be a relevant parameter.

Next, experimental study of spreading of glycerol droplets on the chemically stripe-patterned silicon wafers done with a fast camera is presented. Two regimes of spreading can be observed during spreading based on droplet base diameter evolution analyzed within r(t)  tn power law frame. In the first, inertial regime, the spreading is dictated by the liquid deposited, and is weakly dependent on the properties of the underlying surface. The circular shape of contact area while spreading is maintained. In the ensuing viscous regime, the interactions between the liquid and underlying pattern come to the first plan. The droplet distorts from spherical shape to adopt elongated morphology that corresponds to the minimum energy configuration on stripe-patterned surfaces. The difference in evolution of droplet base in directions parallel and perpendicular to the stripes are studied.
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The 10th Complex Motion in Fluids 2021
Max Planck Gesellschaft
Centre for Scientific Computing