Wetting dynamics on superhydrophilic surfaces prepared by photonic microfolding

Area of Science:

• Surface Science
• Wettability Studies
• Polymer Coatings

Background:

• Understanding wetting dynamics is crucial for applications involving liquid-surface interactions.
• Superhydrophilic surfaces exhibit unique spreading behaviors influenced by surface roughness.
• Existing models like Tanner's law and McHale's model attempt to describe wetting dynamics.

Purpose of the Study:

• To investigate the wetting dynamics of water droplets on microrough, superhydrophilic acrylate surfaces.
• To compare experimental results with existing theoretical models for wetting dynamics.
• To analyze the initial spreading phase and its deviation from established models.

Main Methods:

• Fabrication of microrough, superhydrophilic acrylate surfaces on poly(ethyleneterephthalate) (PET) films.
• Optical recording of water droplet spreading dynamics through transparent acrylate layers.
• Analysis of the dynamic spreading radius (rc(t)) and comparison with Tanner's law and McHale's model.

Main Results:

• Experimental wetting dynamics generally agreed with McHale's model for superhydrophilic surfaces.
• A significant deviation was observed in the initial spreading phase (t < 1 s).
• The initial spreading behavior aligns with the Cazabat and Cohen Stuart theory for rough surfaces.

Conclusions:

• McHale's model provides a good approximation for wetting dynamics on these surfaces, but requires refinement for the initial phase.
• The initial spreading on microrough surfaces is distinct and can be described by a different power-law regime.
• This study highlights the importance of considering surface roughness in wetting dynamic models, especially at early stages.