Cyclic Epipedography─Monitoring Contact Angle Changes in Dipping a Microsphere into a Liquid and Lifting from It

Area of Science:

• Surface Science
• Materials Science
• Physical Chemistry

Background:

• Wetting characteristics of microspheres are vital for understanding surface interactions.
• Existing methods for monitoring surface wetting can be limited in scope and precision.
• Developing novel techniques to characterize dynamic surface properties is essential.

Purpose of the Study:

• To introduce cyclic epipedography as a novel method for monitoring microsphere wetting.
• To analyze the dynamic wetting behavior of silica microspheres.
• To investigate the environmental conformity and Janus characteristics of modified silica surfaces.

Main Methods:

• Fabrication of nearly perfect silica microspheres (0.5-0.6 mm) from optical fibers.
• Utilizing cyclic epipedography with a horizontally held microscope to track liquid line levels.
• Analysis of cyclic epipedograms (plots of liquid line level vs. liquid plane level) to determine contact angles.

Main Results:

• Cyclic epipedograms provide a closed-loop representation of dip-lift cycles.
• The method successfully estimated contact angles at various stages of the wetting cycle.
• Surface modification with aminopropyldimethylethoxysilane induced environmental conformity and Janus characteristics in silica microspheres.

Conclusions:

• Cyclic epipedography is an effective technique for characterizing dynamic wetting phenomena.
• Silica microspheres treated with specific silanes exhibit adaptive surface properties, conforming to their environment.
• The observed Janus characteristics are dependent on the degree of surface modification and the surrounding medium.