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One technique used at imo-imomec to investigate surfaces is the sessile drop method. This is an optical contact angle method and is used to estimate wetting properties of a localized region on a solid surface. This is ideal for curved samples or where one side of the sample has different properties than the other.
The sessile drop method is performed with the OCA 15 Plus. This device deposits drops of different volumes very accurately and precise and a video camera records the droplet as function of time and later the contact angle is evaluated with a software package.
If the contact angle is low and a water droplet is used, the surface is hydrophilic. If the contact angle is high and a water droplet is used, the surface is hydrophobic. This way the hydrophilicity (wetting) of solid surfaces can be measured.
By depositing different fluids like water, ethylene glycol and diiodomethane, free surface energies can be evaluated by using the Owens, Wendt, Rabel and Kaelble method (OWRK) or other general accepted methods.