Dynamic contact angle measurements on lubricant infused surfaces

Area of Science:

• Surface Science
• Fluid Dynamics
• Materials Science

Background:

• Lubricant-infused surfaces (LISs) offer tunable fluid mobility but lack quantitative slipperiness measures.
• Understanding LIS behavior is crucial for applications in microfluidics, anti-fouling, and drag reduction.

Purpose of the Study:

• To quantify the slippery property of LISs by measuring dynamic contact angles.
• To develop a scaling model for predicting LIS performance based on fluid dynamics.

Main Methods:

• Fabricated LISs by infusing lubricants of varying viscosities into a polytetrafluoroethylene surface.
• Measured apparent dynamic advancing and receding contact angles using a modified Wilhelmy plate technique.
• Varied capillary number and lubricant viscosity during immersion/withdrawal in aqueous glycerol-water solutions.

Main Results:

• Dynamic contact angles on LISs were sensitive to lubricant viscosity and capillary number.
• A scaling law, θD³ ~ Ca¹, was established, aligning with hydrodynamic theory.
• Decreasing lubricant viscosity shifted the dynamic contact angles towards higher capillary numbers.

Conclusions:

• Dynamic contact angles provide a quantitative measure of LIS slipperiness.
• The derived scaling law accurately predicts LIS performance across different conditions.
• This study offers a novel method for characterizing and designing LISs.