Zwitterionic Copolymer-Regulated Interfacial Polymerization for Highly Permselective Nanofiltration Membrane.

Area of Science:

• Materials Science
• Chemical Engineering
• Polymer Chemistry

Background:

• Developing highly permselective nanofiltration membranes is crucial for efficient water desalination.
• Interfacial polymerization (IP) is a common method for creating thin-film composite membranes, but controlling membrane thickness and pore structure remains a challenge.

Purpose of the Study:

• To engineer a highly permselective nanofiltration membrane with improved water permeance and salt rejection.
• To investigate the role of zwitterionic copolymer assembly in regulating interfacial polymerization for membrane fabrication.

Main Methods:

• Synthesized a zwitterionic copolymer, P[MPC-co-AEMA], via free-radical polymerization.
• Employed the P[MPC-co-AEMA] copolymer to regulate interfacial polymerization (IP) for polyamide (PA) membrane formation.
• Incorporated the P[MPC-co-AEMA] into the PA matrix to form ridge-shaped nanofilms with controlled internal architecture.

Main Results:

• Fabricated an ultrathin PA membrane (70 nm) with P[MPC-co-AEMA] incorporation, significantly thinner than pristine PA (230 nm).
• Achieved a high water permeance of 15.7 L·m⁻²·h⁻¹·bar⁻¹, over three times that of pristine PA (4.4 L·m⁻²·h⁻¹·bar⁻¹).
• Demonstrated high divalent salt rejection (98.3%) and competitive mono-/divalent ion selectivity (52.9).

Conclusions:

• Zwitterionic copolymer assembly effectively regulates IP, leading to thinner and more interconnected PA membranes.
• The P[MPC-co-AEMA]-incorporated PA membrane exhibits superior performance for desalination compared to state-of-the-art membranes.
• This approach offers a promising strategy for designing advanced nanofiltration membranes with enhanced separation properties.