Fabrication of an Inverse Size-Selective Membrane Using an Electrospun Nanofiber Mat as a Template

Area of Science:

• Materials Science
• Chemical Engineering
• Nanotechnology

Background:

• Nanoporous membranes are crucial for water purification and separation processes.
• Existing fabrication methods, like block copolymer self-assembly, are often expensive.
• Electrospinning offers a scalable route to polymer nanofibers but requires further processing for membrane applications.

Purpose of the Study:

• To develop a cost-effective and generalizable method for fabricating inverse nanoporous membranes.
• To investigate methods for enhancing membrane flux and controlling pore size selectivity.
• To explore the relationship between nanofiber fusion, annealing conditions, and final membrane performance.

Main Methods:

• Fabrication of nanofiber mats via electrospinning.
• Thermal annealing of nanofiber mats under pressure to induce fiber fusion.
• Infusion of a second polymer into the inter-fiber voids.
• Removal of the nanofiber template to create inverse porous membranes.
• Plasma etching of the final membrane surface to expose nanochannels.

Main Results:

• Membrane flux was significantly increased by thermal annealing and plasma etching.
• The size selectivity of the membranes was governed by the pore size at the junctions of fused nanofibers/nanotubes.
• Increased thermal annealing temperature led to larger pore sizes at the junctions.
• The developed method is versatile for various polymer materials.

Conclusions:

• A novel, cost-effective method for fabricating inverse nanoporous membranes was successfully developed.
• The process allows for tuning membrane flux and size selectivity through controlled nanofiber fusion and surface treatment.
• This technique holds promise for advanced filtration and separation applications.