Nucleated dewetting in supported ultra-thin liquid films with hydrodynamic slip

Area of Science:

• Materials Science
• Surface Chemistry
• Polymer Physics

Background:

• Dewetting of ultra-thin polymer films is crucial in various applications.
• Understanding the influence of surface properties on film dynamics is essential.
• Existing models often assume no-slip boundary conditions, which may not always apply.

Purpose of the Study:

• To investigate the effect of surface energy and solid/liquid boundary conditions on polymer film dewetting.
• To elucidate the transition in breakup mechanisms from spinodal to nucleation and growth.
• To explore the relationship between film thickness, temperature, and hole density.

Main Methods:

• Modification of SiO2 substrates using silane self-assembled monolayers to control hydrophobicity and slip.
• High-speed in situ atomic force microscopy (AFM) to observe real-time film breakup.
• Application of a free energy model to infer critical nucleus size.

Main Results:

• Hydrophobic surfaces with slip conditions shifted the breakup mechanism from spinodal to nucleation and growth.
• Hole density exhibited a clear dependence on film thickness and temperature.
• Experimental observations supported the theoretical inference of a critical nucleus size.

Conclusions:

• Surface energy and hydrodynamic slip significantly alter ultra-thin polymer film dewetting.
• The nucleation and growth mechanism, driven by critical nucleus size, becomes dominant under specific surface conditions.
• Findings provide insights into bursting unsupported films and guide material design.