Capillary Bridges on Hydrophobic Surfaces: Analytical Contact Angle Determination

Area of Science:

• Surface Science
• Physical Chemistry
• Materials Science

Background:

• The capillary bridge probe method accurately determines contact angles on hydrophilic surfaces.
• Hydrophobic surfaces present challenges due to incomplete liquid bridge shapes, hindering analytical evaluation.

Purpose of the Study:

• To adapt and validate the capillary bridge probe method for contact angle measurements on hydrophobic surfaces.
• To classify incomplete liquid bridge shapes and develop a novel analytical procedure for their evaluation.

Main Methods:

• Studied the behavior of r-ϑ type liquid bridges on hydrophobic surfaces.
• Classified incomplete liquid bridge shapes and developed a novel analytical procedure based on Delaunay's solution.
• Visualized and described the parameter space of capillary bridges without dimensionless variables.

Main Results:

• Successfully determined contact angles on hydrophobic surfaces, including Cyclo Olefin Polymer and PTFE.
• Advancing and receding contact angles were measured and compared with sessile drop methods.
• The novel procedure enables analytical evaluation of incomplete capillary bridge shapes.

Conclusions:

• The capillary bridge probe method is effective for contact angle measurements on hydrophobic surfaces.
• The developed classification and analytical procedure overcome limitations of incomplete liquid bridge shapes.
• This method provides accurate contact angle data for hydrophobic materials, complementing existing techniques.