Condensation or Desublimation: Nanolevel Structural Look on Two Frost Formation Pathways on Surfaces with Different...

Area of Science:

• Physical Chemistry
• Materials Science
• Surface Science

Background:

• Water condensation and desublimation are vital natural and industrial processes.
• Understanding nanoscale phase transitions, especially initial nucleation stages, remains challenging.
• Advanced characterization methods are needed to probe these phenomena in real-time.

Purpose of the Study:

• To investigate water/ice nucleation pathways during frosting from vapor onto surfaces with varying wettabilities.
• To elucidate the influence of substrate properties and vapor supersaturation on phase transition mechanisms.
• To provide a nanoscopic understanding of the initial stages of frost formation.

Main Methods:

• Utilized synchrotron grazing-incidence wide-angle X-ray scattering (GIWAXS) for structural and orientational analysis.
• Employed environmental scanning electron microscopy (ESEM) for real-time imaging of frosting processes.
• Studied substrates ranging from highly hydrophilic to superhydrophobic.

Main Results:

• Observed diverse frosting scenarios, including direct desublimation and condensation-freezing pathways.
• GIWAXS provided quantitative insights into crystallinity and ordering during ice nucleation.
• ESEM visualized distinct frost formation mechanisms influenced by substrate wettability and supersaturation.
• Classical nucleation theory accurately predicted pathways for hydrophobic surfaces.

Conclusions:

• The study reveals distinct water/ice nucleation pathways dependent on substrate wettability and vapor conditions.
• Classical nucleation theory successfully describes frosting on hydrophobic surfaces but requires refinement for hydrophilic ones.
• The findings offer a deeper understanding of frost formation crucial for industrial applications and natural phenomena.