For calculate the surface energy we use the Owens - Wendt approach based on Young's equation:
γS = γSL + γL cosθ,
where γS is the surface free energy of the solid in mJ/m2, γSL is the interfacial
free energy between solid and liquid, γL is the surface tension of the liquid,
and θ is the contact angle.
Please, what are the values of γSL and γL when I use distilled water to calculate the contact angle ?.
Moreover, do these values depend on the volume of the water drop and the temperature of the environment?
Distilled water is water without impurities. The purities in water (e.g. salt inons) gegeral redece water surafce tension because it makes water hydrophilic a bit. Typically water surface tension of water is 72.8 mN/m at RM. So I distilled water surafce tension would be no less than this value.
γSL is the interfacial surface tension, which is model-dependent. see the paper ( Article Binary Liquid Mixture Contact-Angle Measurements for Precise...
) and how to calculate it using Owens-Wendt model.γL is interfacial surface tension at liquid-gas interface, which is basically liquid surface tension and can be easily found in literature.
Those values are fundamentally independent on volume as those are molecular interaction. Those interaction would depend on material type and thermodynamic variables such as temperature, pressure, composition, etc., but not on extensive properties such as volume, mass, etc.
1. Tomasz Białopiotrowicz et al., Surface Properties of Gelatin Films, Langmuir, 2002, 18, 9462-9468.
2. Motoyasu Kobayashi et al., Wettability and Antifouling Behavior on the Surfaces of Superhydrophilic Polymer Brushes, Langmuir, 2012, 28, 7212-7222.
Please see the attached where we present a new method of surface energy estimate based on thermo dynamic considerations. Dan Fleming
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