Drying of a 75μL droplet of 8% poly(ethylene oxide) solution in water. The duration of the experiment was approximately 2 hours, the distance...
Drying of a 75μL droplet of 8% poly(ethylene oxide) solution in water. The duration of the experiment was approximately 2 hours, the distance across the image approximately 10mm. Timings given below are given relative to the video, to aid identification of the various stages and processes.
The droplet exhibits pinned drying (stage 1) for around the first 5 seconds, at which point the contact line depins and the droplet undergoes a dewetting transition (stage 2) until 9 seconds. At this time the contact angle remains constant at just over 90 degrees, and the droplet climbs on top of the solid deposit, bootstrap building (stage 3). At 11 seconds the outer surface appears completely solid and the maximum height is reached. Stage 4 drying follows as the solid shape slowly shrinks. The base radius of the final cone is less than a quarter of that of the initial droplet.