Electrowetting of Ionic Liquids in Solid–Liquid–Liquid Systems - Drops and Bubbles in Contact with Solid Surfaces - page 253

Figure 9. Static contact angle, θ , as a function of the applied DC voltage, V , for a droplet of ionic
liquid immersed in hexadecane on an electrode insulated with Teflon AF1600. The solid lines are
the best fit of the Young-Lippmann equation. Reprinted with permission from Paneru et al. [51].
Copyright 2011 VSP.

Figure 10. Static contact angle, θ , as a function of the applied DC voltage, V , for a droplet of a
bmim.BF 4 -water mixture immersed in hexadecane on an electrode insulated with Teflon AF1600.
The solid lines are the best fit of the Young-Lippmann equation. The dashed line indicates the satu-
ration contact angle, θ S . Adapted with permission from Paneru et al. [49]. Copyright 2010 American
Chemical Society.

to saturation. As the water content increases, both the contact angle at zero voltage,
θ 0 , and the saturation voltage, V S , increase. The saturation contact angle is essen-
tially constant ( 50 ◦ , dashed line). The electrowetting curves obtained with AC

voltage (Fig. 11) are similar and again electrowetting performance is better though
the improvement over DC voltage diminishes as water content increases.

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