Wetting phenomena occur daily around us and are relevant for numerous
applications. Still, the dynamics of wetting is poorly understood. This
is particularly true for water. With respect to wetting, water is
distinct due to its relatively high surface tension, low viscosity and
high dielectric permittivity.
One
particularly interesting questions is: which effect do molecular or
nanoscopic defects have on the dynamics of wetting? Can one for example
control the speed of a drop sliding down an inclined plate by defects?
Since the motion of moving drops is determined by processes at the
contact line, the goal is to image the effect of defects on the motion
of contact lines.
To aschieve this goal, we have build a high speed / high resolution reflection microscopy setup and use it to image the front and rear contact lines of drops moving down tilted samples.
Reflection microscopy setup Water sliding on PFOTS coated glass slide. Image width 380 microns.