Dynamic wetting of a fluoropolymer surface by ionic liquids

Area of Science:

• Surface Science
• Materials Chemistry
• Physical Chemistry

Background:

• Ionic liquids (ILs) exhibit unique properties making them suitable for various applications.
• Fluoropolymer surfaces, like Teflon AF1600, present specific wetting challenges.
• Understanding IL-surface interactions is crucial for advanced material design.

Purpose of the Study:

• To investigate the spontaneous spreading of six different ionic liquids on a Teflon AF1600 surface.
• To analyze the dynamic contact angle dependence on contact line velocity.
• To evaluate the applicability of hydrodynamic and molecular-kinetic models in describing this phenomenon.

Main Methods:

• High-speed video microscopy was employed to observe the spreading dynamics.
• Six ionic liquids, including EMIM BF(4) and BMIM NTf(2), were used as probe liquids.
• Hydrodynamic and molecular-kinetic models were utilized for data interpretation.

Main Results:

• The hydrodynamic model showed limited usefulness in explaining the observed spreading.
• A strong correlation was found between the molecular dimensions of ILs and the parameters of the molecular-kinetic model.
• Energy dissipation was identified in both the bulk liquid and at the contact line during dynamic wetting.

Conclusions:

• The molecular-kinetic model provides a better framework for understanding IL spreading on fluoropolymers than hydrodynamic models.
• Dynamic wetting involves energy dissipation mechanisms at both macroscopic and microscopic scales.
• These findings have significant implications for lubrication, biological interfaces, and resource recovery processes.