Molecular Transport within Polymer Brushes: A FRET View at Aqueous Interfaces.

Area of Science:

• Polymer Science
• Surface Chemistry
• Materials Science

Background:

• Molecular permeability in polymer brushes is crucial for surface lubrication, wettability, and solute transport.
• Understanding polymer nanostructure and chain conformation is key to controlling permeability.
• Existing methods for probing transport within polymer brushes have limitations.

Purpose of the Study:

• To develop and utilize a novel polymer brush system for studying molecular transport.
• To investigate the movement of fluorophores from aqueous droplets into polymer brushes.
• To correlate molecular transport dynamics with surface properties like wettability and lubrication.

Main Methods:

• Fabrication of ultrathin polymer brushes from N-isopropylacrylamide and a FRET donor-labeled monomer.
• Utilizing Förster Resonance Energy Transfer (FRET) to monitor fluorophore transport.
• Spatially analyzing FRET signals around the three-phase contact line of aqueous droplets placed on the brush surface.

Main Results:

• Demonstrated successful tracking of fluorophore transport from droplets into the polymer brush.
• Observed time-dependent changes in fluorophore distribution as droplets receded.
• Identified a strong dependence of molecular transport dynamics on relative humidity.

Conclusions:

• The developed FRET-based polymer brush system effectively probes molecular transport dynamics.
• This system provides insights into the relationship between molecular movement, surface wettability, and lubrication.
• The findings are applicable to understanding and designing surfaces for controlled wetting and lubrication.