Controllable and Gradient Wettability of Bilayer Two-Dimensional Materials Regulated by Interlayer Distance

Area of Science:

• Materials Science
• Surface Science
• Nanotechnology

Background:

• Controlling surface wettability typically involves complex microstructures or external stimuli.
• Existing methods for wettability modulation often rely on intricate mechanisms that are difficult to quantify.

Purpose of the Study:

• To propose an online strategy and theoretical model for controlling surface wettability using bilayer graphene-like atomic structures.
• To investigate the relationship between interlayer distance, material properties, and overall surface wettability.
• To demonstrate the creation of gradient wettability surfaces for inducing droplet motion.

Main Methods:

• Utilized molecular dynamics simulations to study the wettability of bilayer graphene-like structures.
• Developed a theoretical model based on the work of adhesion to describe surface wettability.
• Created gradient wettability surfaces by inclining the bottom material layer.

Main Results:

• Surface wettability shifts towards hydrophilicity upon adding a bottom material, with the effect diminishing as interlayer distance increases.
• The work of adhesion explains the observed wettability variations and provides insight into graphene's wetting transparency.
• A theoretical model successfully correlates overall wettability with interlayer distance and individual material properties.
• Gradient wettability surfaces were fabricated, enabling spontaneous droplet motion.

Conclusions:

• A novel strategy for controllable wetting and gradient surfaces using 2D materials is presented.
• The theoretical model offers a quantitative understanding of wettability control in bilayer systems.
• The developed surfaces show potential for applications in microfluidic chips, diagnostics, and sensors.