Defect Repair of Polyelectrolyte Bilayers Using SDS: The Action of Micelles Versus Monomers

Area of Science:

• Materials Science
• Surface Chemistry
• Separation Technology

Background:

• Polyelectrolyte multilayers (PEMs) are widely used in various applications.
• Defects in PEMs can compromise their performance.
• Effective repair strategies for PEM defects are needed.

Purpose of the Study:

• To investigate the repair of defects in polyelectrolyte bilayers using sodium dodecyl sulfate (SDS).
• To compare the efficacy of monomeric and micellar SDS solutions for defect repair.
• To evaluate the potential of repaired bilayers for gas separation.

Main Methods:

• Fabrication of single, double, and triple polyelectrolyte bilayers using poly(sodium 4-styrenesulfonate) (PSS) and poly(diallyldimethyammonium chloride) (PDDA).
• Repair of bilayer defects using aqueous solutions of SDS (monomeric and micellar).
• Characterization of repaired bilayers using atomic force microscopy, X-ray photoelectron spectroscopy, ellipsometry, and contact angle measurements.
• Measurement of CO2 and N2 permeance and selectivity.

Main Results:

• Aqueous SDS solutions effectively repaired defects in PSS/PDDA bilayers, reducing permeability and increasing selectivity.
• Micellar SDS solutions were more effective than monomeric solutions, repairing all tested bilayer thicknesses.
• Repaired single bilayers exhibited CO2 permeances of ~200 GPU and CO2/N2 selectivities of ~30.
• Surface analysis confirmed the deposition of SDS micelles or fragments on repaired bilayers.

Conclusions:

• Micellar SDS is a highly effective agent for repairing defects in PSS/PDDA polyelectrolyte bilayers.
• The repaired bilayers demonstrate promising performance for CO2/N2 separation.
• Further development of these SDS-repaired assemblies holds practical potential for flue gas treatment.