Water-repellent hydrophilic nanogrooves

Area of Science:

• Surface Science and Nanotechnology
• Fluid Dynamics at the Nanoscale

Background:

• Understanding liquid behavior on nanostructured surfaces is crucial for microfluidics and material design.
• The interplay between surface geometry, roughness, and liquid wettability governs capillary phenomena.

Purpose of the Study:

• To investigate the wetting dynamics of a nanodrop on nanogrooves with varying surface properties.
• To determine critical contact angles for groove impregnation and identify different wetting regimes.
• To explore the influence of surface roughness and groove geometry on liquid imbibition.

Main Methods:

• Simulations employing many-body dissipative particle dynamics (DPD).
• Geometric analysis using the Surface Evolver computational method.
• Systematic variation of surface roughness, groove structure, and drop volume.

Main Results:

• Three distinct wetting regimes were identified based on the intrinsic contact angle and critical angles.
• Surface roughness and specific groove structures (shallow pits, trenches) significantly reduce critical contact angles, hindering impregnation.
• Wetting is dependent on both surface chemistry (contact angle) and topography, with topography playing a dominant role in preventing impregnation.

Conclusions:

• Surface structure within nanogrooves is a critical factor for controlling liquid imbibition.
• Hydrophilic cavities that prevent liquid impregnation can be fabricated by engineering surface topography, independent of chemical modifications.
• This provides a pathway for designing surfaces with tunable wettability for advanced applications.