Polyelectrolyte Complex Hollow Fiber Membranes Prepared via Aqueous Phase Separation

Area of Science:

• Materials Science
• Chemical Engineering
• Polymer Science

Background:

• Conventional hollow fiber (HF) membrane production relies on hazardous organic solvents like N-methyl pyrrolidone.
• Aqueous phase separation (APS) offers a sustainable alternative using water as both solvent and non-solvent.
• There is a need for environmentally friendly methods in polymeric membrane manufacturing.

Purpose of the Study:

• To demonstrate the first-time preparation of sustainable and functional HF membranes using the APS technique.
• To investigate the dry-jet wet spinning process for APS-based HF membrane fabrication.
• To explore the influence of bore liquid and coagulation bath composition on membrane properties.

Main Methods:

• Utilized poly(sodium 4-styrenesulfonate) (PSS) and polyethyleneimine (PEI) dope solution at high pH.
• Employed an aqueous bore liquid and a low pH acetate buffer coagulation bath in a dry-jet wet spinning process.
• Systematically varied bore liquid and coagulation bath compositions to control precipitation rate and membrane structure.

Main Results:

• Achieved microfiltration-type membranes with high permeability (500-800 L·m⁻²·h⁻¹·bar⁻¹) and complete emulsion droplet retention under slow precipitation conditions.
• Produced ultrafiltration-type membranes with lower permeability (12-15 L·m⁻²·h⁻¹·bar⁻¹) and molecular weight cut-offs of 7.8-11.6 kDa by increasing acetate buffer concentration and precipitation rate.
• Demonstrated the formation of a polyelectrolyte complex between PSS and PEI upon PEI charging in the coagulation bath.

Conclusions:

• Confirmed the versatility and feasibility of the APS technique for producing functional HF membranes.
• Successfully fabricated HF membranes with tunable properties (microfiltration to ultrafiltration) via APS.
• This research advances APS as a viable, large-scale alternative to conventional solvent-based membrane production methods.