Asymmetric wetting hysteresis on chemical defects

Area of Science:

• Surface Science
• Materials Science
• Physical Chemistry

Background:

• Wetting phenomena are crucial in various scientific and industrial applications.
• Hysteresis in wetting, characterized by different advancing and receding contact angles, is a complex behavior.
• The influence of chemical defects on wetting hysteresis remains an area of active investigation.

Purpose of the Study:

• To investigate the role of chemical defects in hysteretic wetting behavior.
• To differentiate the effects of high-energy versus low-energy defects on wetting dynamics.
• To elucidate the mechanisms behind asymmetric wetting hysteresis.

Main Methods:

• Utilized the Wilhelmy plate technique to measure wetting and dewetting forces.
• Systematically varied the energy of chemical defects within a material matrix.
• Compared experimental wetting and dewetting data against equilibrium wetting theories.

Main Results:

• Wetting and dewetting work showed significant differences based on defect energy.
• High-energy defects caused advancing measurements to deviate from equilibrium theory, while receding data agreed.
• Low-energy defects resulted in receding measurements deviating from theory, with advancing data in agreement.
• Observed asymmetric hysteresis where either advancing or receding contact angles deviated more strongly from equilibrium.

Conclusions:

• Distinct wetting mechanisms govern the behavior of high- and low-energy defects.
• The energy landscape of chemical defects dictates the asymmetry in wetting hysteresis.
• Understanding these defect-driven mechanisms is key to controlling and predicting wetting behavior.