Partial wetting of chemically patterned surfaces: the effect of drop size

Area of Science:

• Physical Chemistry
• Surface Science
• Materials Science

Background:

• Understanding partial wetting on chemically heterogeneous substrates is crucial for various applications.
• Previous studies often focused on two-dimensional models or simpler chemical patterns.
• The behavior of three-dimensional sessile drops on complex surfaces requires further investigation.

Purpose of the Study:

• To simulate and analyze the partial wetting behavior of three-dimensional sessile drops on chemically heterogeneous substrates.
• To investigate the influence of drop volume on equilibrium configurations and contact angle characteristics.
• To compare wetting behavior across different chemical patterns and dimensionalities.

Main Methods:

• Three-dimensional simulations of sessile drops in equilibrium with smooth surfaces.
• Surfaces feature ordered chemical patterns.
• Analysis of drop volume, shape, contact line, average contact angle, and contact angle hysteresis.

Main Results:

• The number of equilibrium drops either remains constant or increases with growing drop volume.
• Larger drops approximate spherical caps, and their contact lines become more circular.
• Average contact angles approach Cassie's prediction with increasing volume, and hysteresis shows volume dependence.

Conclusions:

• Drop volume significantly impacts the equilibrium, shape, and wetting angles of partial wetting systems.
• Three-dimensional drops exhibit distinct behaviors compared to two-dimensional models, influenced by pattern constraints.
• The findings provide insights into the complex interplay of surface chemistry, drop size, and wetting phenomena.