Fig. 1
From: Wetting transitions in droplet drying on soft materials
Sessile droplets drying on rigid and compliant substrates. Image sequence of sessile droplets evaporating from, a rigid (PDMS Sylgard 184 9:1, E = 2937 kPa) and, b compliant (bottom-row, PDMS Sylgard 184 50:1, E = 20 kPa20) substrates (environmental conditions: rH = 50% and T = 24.1 ± 0.5 °C). Location of the temperature measurement, T, is shown in Fig. 2a. c Schematic of a droplet on a compliant substrate and resulting deformation. We defined the apex region as the portion of the wetting ridge which has a width less than ΥS/E. d Experimentally measured apparent contact angle, θ*, vs. time, t, of the droplets in (a) and (b) (empty diamonds: rigid; filled diamonds: compliant). e Experimentally measured contact radius, R, vs. t of the droplets in (a) and (b) (empty diamonds: rigid; filled diamonds: compliant). f θ* vs. normalized contact radius, R/R0, where R0 is the value of R at t0, for rH values of 15 ± 1% (dotted line), 50 ± 1% (dashed line), and 90 ± 1% (solid line) on rigid (black) and compliant (red) substrates. Each line corresponds to the average of nine independent measurements; fine lines represent the standard deviations. Scale bar: a, b 200 µm. Source data are provided as a Source Data file for (d–f)
