Construction of metal-ligand-coordinated multilayers and their selective separation behavior

Area of Science:

• Materials Science
• Polymer Chemistry
• Nanotechnology

Background:

• Layer-by-layer (LbL) assembly is a versatile technique for fabricating multilayered thin films.
• Coordination polymers offer unique properties for various applications, including separation.
• Developing robust multilayer membranes on diverse substrates remains a challenge.

Purpose of the Study:

• To explore the layer-by-layer (LbL) assembly of a coordination multilayer using metal-ligand interactions.
• To investigate the properties and separation performance of these multilayers on planar and 3D substrates.
• To demonstrate the potential of this technique for creating advanced separation membranes.

Main Methods:

• Alternate deposition of transition-metal-containing polyelectrolyte (Co(2+)-exchanged poly(styrene sulfonate), PSS) and ligand-containing polymer (poly(4-vinyl pyridine), P4VP).
• Characterization using UV-vis, FTIR, XPS, profilometry, SEM, AFM, and contact angle analysis.
• Assembly on flat sheet and hollow fiber polymeric porous substrates via a dynamic pressure-driven LbL technique.

Main Results:

• Successful formation and characterization of the Co(2+)-PSS/P4VP coordination multilayer.
• Demonstrated high dehydration performance for solvent-water mixtures.
• Achieved permselectivity for aromatic compounds and water-softening capacity.
• Successful assembly on hollow fiber substrates using the dynamic pressure-driven LbL method.

Conclusions:

• Metal-ligand-coordinated self-assembly is a powerful method for preparing separation membranes.
• The dynamic pressure-driven LbL technique enables multilayer construction on complex 3D porous substrates.
• This approach holds significant promise for developing a range of separation membranes for diverse applications.