Fouling- and Chlorine-Resistant Nanofiltration Membranes Fabricated from Charged Zwitterionic Amphiphilic Copolymers
Samuel J. Lounder, Ayşe Asatekin
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(Na2SO4) = 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.