As-placed contact angles for sessile drops

• Published in: Journal of colloid and interface science Vol. 317; no. 1; pp. 241 - 246
• Main Authors: Tadmor, Rafael, Yadav, Preeti S.
• Format: Journal Article
• Language: English
• Published: San Diego, CA Elsevier Inc 2008; Elsevier
• Subjects: Advancing contact angle; Chemistry; Colloidal state and disperse state; Exact sciences and technology; General and physical chemistry; Hydrostatic pressure; Interfacial tension; Line energy; Line tension; Receding contact angle; Surface physical chemistry; Surface tension; Three phase contact line; Young contact angle; Young equation; Young equation; Line energy; Interfacial tension; Hydrostatic pressure; Line tension; Receding contact angle; Three phase contact line; Surface tension; Young contact angle; Advancing contact angle; Interface tension; Equation; Contact angle; Drop; Contact line; Hydrostatics; Energy; Sessile; Physicochemical properties
• ISSN: 0021-9797; 1095-7103
• DOI: 10.1016/j.jcis.2007.09.029

As-placed contact angle is the contact angle a drop adapts as a result of its placement on a surface. As expected, the as-placed contact angle, θ AP , of a sessile drop on a horizontal surface decreases with the drop size due to the increase in hydrostatic pressure. We present a theoretical prediction for θ AP which shows that it is a unique function of the advancing contact angle, θ A , drop size, and material properties (surface tensions and densities). We test our prediction with published and new data. The theory agrees with the experiments. From the relation of the as-placed contact angle to drop size the thermodynamic equilibrium contact angle is also calculated.