(401ac) Zwitterionic Polymer Membranes for the Separation of Biomass Derived Mixture

Zwitterionic polymers have rich positively and negatively charged functional groups. The high polarity enables effectively solvation with water molecules, establishing a strong hydration layer around the polymer chains. The hydrated layers prevent the polymer surface from interacting with fouling agents, granting antifouling properties. The great antifouling properties make zwitterionic polymer membranes highly attractive for water treatment involving complex feed. Producing chemicals and fuels from biomass, such as microalgae, macroalgae and lignin, are important to ensure sustainable supply of feedstock chemicals and fuels to meet the growing demands. After chemical or bio reactions, the products are typically complex mixtures to be separated before usage. This research aims to develop effective zwitterionic polymer membranes with excellent antifouling properties for separating aqueous mixture generated from biomass into different partitions. Zwitterionic polymer membranes are advantageous over conventional polymer membranes for such separations but rarely studied.

The zwitterionic copolymer is synthesized with zwitterionic monomer and another monomer for property tuning. An ultrathin zwitterionic copolymer layer is then coated on an ultrafiltration polymer substrate to form a composite membrane with minimal transport resistance. This study explores the use of atom transfer radical polymerization (ATRP) to tune the effective membrane pore size suitable for separating water and organic molecules through different levels of crosslinking. Separation tests are conducted to understand the membrane pore size influence on membrane separation performance for the biomass derived aqueous mixture. Additionally, we expect our modifications to provide strong antifouling characteristics, which is a widely known consequence of long-term membrane application failure. The membrane antifouling property is studied with long-term separation tests and compared with other polymer membranes. This research aims to achieve membranes with great selectivity and excellent antifouling properties, thus presents an exciting step forward for sustainable and energy-efficient production of chemicals and fuels.