Spectroscopic ellipsometry as a complementary tool to characterize coatings on PDMS for CE applications

Area of Science:

• Materials Science
• Surface Chemistry
• Analytical Chemistry

Background:

• Polyelectrolyte adsorption on surfaces is crucial for fabricating functional thin films.
• Understanding adsorption mechanisms guides the development of advanced materials.
• Polydimethylsiloxane (PDMS) is a versatile substrate for surface modification.

Purpose of the Study:

• To investigate the adsorption of poly(diallyldimethylammonium chloride) (PDDAC) and poly(styrenesulfonate) (PSS) onto PDMS thin films.
• To determine the optimal conditions for polyelectrolyte adsorption and multilayer fabrication.
• To evaluate the performance of fabricated multilayer constructs in separating phenolic compounds.

Main Methods:

• Spectroscopic ellipsometry was employed to monitor polyelectrolyte adsorption kinetics and film thickness.
• Atomic force microscopy (AFM) provided surface morphology and roughness data.
• Contact angle measurements assessed surface wettability changes.
• Capillary electrophoresis (CE) was used to evaluate separation efficiency of phenolic compounds.

Main Results:

• Spectroscopic ellipsometry successfully characterized the adsorption process of PDDAC and PSS on PDMS.
• Optimal adsorption conditions were identified, enabling the fabrication of multilayer films from 1 to 20 nm.
• Polyelectrolyte layers approximately 10 nm thick demonstrated superior performance in separating phenolic compounds by CE.

Conclusions:

• The study successfully optimized polyelectrolyte adsorption on PDMS using spectroscopic ellipsometry.
• Fabricated multilayer polyelectrolyte films, particularly those around 10 nm, significantly improve phenolic compound separation in capillary electrophoresis.
• This research provides a foundation for designing advanced separation media through controlled surface functionalization.