Fouling-Resistant Membranes with Tunable Pore Size Fabricated Using Cross-Linkable Copolymers with High Zwitterion Content

Abstract

• We prepared membranes coated with cross-linkable zwitterionic copolymers. • Cross-linking stabilized water-soluble high-zwitterion content copolymers. • Membrane pore size and permeance was tuned by zwitterion fraction. • Exceptional fouling resistance was achieved. • High-zwitterion content led to previously unobserved salt-responsive behavior. This work describes a new approach for synthesizing extremely fouling-resistant, zwitterionic membranes with controlled, tunable pore sizes that extend from ion separations (< 1 nm) to the ultrafiltration range (∼2 nm). These membranes are manufactured by the UV treatment of high zwitterion content amphiphilic copolymers with cross-linkable functionality to stabilize the membrane selective layers, preventing excessive swelling and dissolution of copolymers containing as high as 80 wt% zwitterionic repeat units. Zwitterion weight fraction allows the tuning of membrane performance, with effective pore size and permeance both increasing with zwitterion content. The high zwitterion content membranes were remarkably fouling-resistant and demonstrated a salt-responsive behavior not previously observed with self-assembling zwitterionic copolymer membranes.