Comparing Contact Angle Measurements and Surface Tension Assessments of Solid Surfaces

Abstract

Four types of contact angles (receding, most stable, advancing, and "static") were measured by two independent laboratories for a large number of solid surfaces, spanning a large range of surface tensions. It is shown that the most stable contact angle, which is theoretically required for calculating the Young contact angle, is a practical, useful tool for wettability characterization of solid surfaces. In addition, it is shown that the experimentally measured most stable contact angle may not always be approximated by an average angle calculated from the advancing and receding contact angles. The "static" CA is shown in many cases to be very different from the most stable one. The measured contact angles were used for calculating the surface tensions of the solid samples by five methods. Meaningful differences exist among the surface tensions calculated using four previously known methods (Owens-Wendt, Wu, acid-base, and equation of state). A recently developed, Gibbsian-based correlation between interfacial tensions and individual surface tensions was used to calculate the surface tensions of the solid surfaces from the most stable contact angle of water. This calculation yielded in most cases higher values than calculated with the other four methods. On the basis of some low surface energy samples, the higher values appear to be justified.

Wettability and corrosion of [NTf2] anion-based ionic liquids on steel and PVD (TiN, CrN, ZrN) coatings

“…Analyzing the evolution of the contact angle of the three ILs (Fig. 4) [67]. Despite of the fact that contact angle reaches the steady state on all surfaces quite fast, measurements are time-dependant and therefore this property does not perfectly define the solid-liquid interaction.…”

The CQ ratio of surface energy components influences adhesion and removal of fouling bacteria

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Physics and applications of superhydrophobic and superhydrophilic surfaces and coatings

“…38 Such measurements are still not very popular because the conventional instruments require considerable modification to accommodate speakers or other vibrationinducing devices. 38,46 Nevertheless, the advancing contact angle and receding contact angle are easily measureable on solids. 31 These two angles are well defined and should always be reported.…”