Ripples Induced by Capillary Rise on a Spherical Particle in a Film of Drying Polymer Solution

We report on the flows associated with the capillary rise occurring when a glass sphere is put into contact with a film of drying polymer solution. A visco-capillary ripple is observed to form at early times and to propagate until it freezes. Its dynamics and final position are in quantitative agreement with those predicted in the frame of the lubrication theory, provided an effective time is introduced, which accounts for the increase in viscosity and decrease in thickness of the drying film. At later times, a secondary ripple forms and we show that its amplitude correlates with the volume of the meniscus. We suggest it results from flows in the drying meniscus, driven by similar effects as in drying droplets and giving way to significant polymer accumulation.