Fouling- and Chlorine-Resistant Nanofiltration Membranes Fabricated from Charged Zwitterionic Amphiphilic Copolymers

Abstract

New polymer chemistries are urgently needed to develop nanofiltration (NF) membranes with improved fouling and chlorine resistance. This work introduces charged zwitterionic amphiphilic copolymers (CZACs), self-assembling terpolymers that spontaneously form a network of ∼1−2 nm hydrophilic nanochannels composed of zwitterionic and acidic/ ionizable building blocks. We leverage CZAC self-assembly to develop membrane filters with anionic nanopores, thereby enabling enhanced salt rejection through Donnan exclusion (R(Na 2 SO 4 ) = 93.6% at 5 mM). The CZAC membranes demonstrate hydraulic permeability comparable to commercial nanofiltration membranes (0.86 − 2.3 L μm m −2 h −1 bar −1 ), exceptional fouling resistance, and a high level of chlorine tolerance (32 000 ppm•h), addressing key performance limitations of current NF membranes.

High Permeance Polyamide Nanofiltration Membranes Based on Poly(l-lactic acid) Electrospun Nanofibrous Membranes with Controlled Hydrophilicity

“…The permeance of the TFNC nanofiltration membranes is about 24% higher than that of the TFC nanofiltration membranes at a similar rejection (Figure S8). Besides, we compared the nanofiltration performance of the TFNC membranes with some nanofiltration membranes reported in other literature and commercial nanofiltration membranes. − TFNC membranes prepared in this work exhibit competitively higher permeance at a similar rejection (Figure a and Table S5). To further evaluate the filtration performance of the TFNC membranes, the long-term stability was investigated.…”

Interface Engineering of Microporous Polypropylene Membranes for Polyamide Thin-Film Composite Nanofiltration Membranes with Robust Structure and Superior Performance

“…Furthermore, we compared TFC membranes prepared in this work with some other nanofiltration membranes reported in other literature studies (Figure b). − Most TFC membranes fabricated on ultrafiltration substrates or other traditional substrates show lower water permeation flux. The present membranes show relatively high water permeation flux of 16.0–21.2 L/m 2 ·h·bar and high Na 2 SO 4 rejection above 95% simultaneously, demonstrating that the TFC membranes fabricated on co-deposited MPPMs have great nanofiltration performance.…”

Influence of Solvent Affinity on Transport through Cross-Linked Copolymer Membranes for Organic Solvent Nanofiltration

“…The copolymer material is designed using varied repeat units with oligomeric side chains that are chemically incompatible with the polymer backbone . The balance between the enthalpic desire of the constituent repeat units to phase separate and their entropic desire to avoid chain stretching results in these copolymer membranes assembling into a continuous network of nanopores between 2 and 5 nm. − Moreover, through synthetic control of the macromolecular chemistry, the pore wall chemistry of copolymer membranes can be altered to increase the strength of the membrane through cross-linking as well as to tailor the membrane for specific separations. − ,, Relevant examples are detailed in reports regarding the fabrication of membranes from a statistical poly­(trifluoroethyl methacrylate- co -oligo­(ethylene glycol) methyl ether methacrylate- co -glycidyl methacrylate) (P­(TFEMA-OEGMA-GMA)) copolymer. , After casting the P­(TFEMA-OEGMA-GMA) copolymer into membranes using both a blade-casting and dip-coating technique, the oxirane groups of the glycidyl methacrylate moieties that line the pore walls are allowed to react with hexamethylenediamine to incorporate positively charged ammonium moieties and cross-link the membrane. Notably, as evidenced by transport experiments as well as nanostructure characterizations, the well-defined nanostructure of the copolymer materials was retained throughout the functionalization process and even after permeating ethanol, which dissolved the copolymer before cross-linking .…”

“…10−14 Moreover, through synthetic control of the macromolecular chemistry, the pore wall chemistry of copolymer membranes can be altered to increase the strength of the membrane through cross-linking as well as to tailor the membrane for specific separations. [10][11][12]15,16 Relevant examples are detailed in reports regarding the fabrication of membranes from a statistical poly(trifluoroethyl methacrylateco-oligo(ethylene glycol) methyl ether methacrylate-co-glycidyl methacrylate) (P(TFEMA-OEGMA-GMA)) copolymer. 11,17 After casting the P(TFEMA-OEGMA-GMA) copolymer into membranes using both a blade-casting and dip-coating technique, the oxirane groups of the glycidyl methacrylate moieties that line the pore walls are allowed to react with hexamethylenediamine to incorporate positively charged ammonium moieties and cross-link the membrane.…”