Design and synthesis of organic polymers for molecular separation membranes
Mathias Ulbricht
Abstract
Nowadays most membrane separation processes utilize membranes made from organic polymers because shape and structure can be tailored to the needs of a specific application with scalable fabrication processes such as solution casting and phase separation, coating and interfacial polymerization. This short review discusses recent progress for membranes suited for molecular separation in aqueous and organic liquids by nanofiltration, dialysis, electrodiaysis or pervaporation. Important achievements for bulk polymers suited as membrane material have been made by special processing of cellulose, development of highly stable polymers, microporous polymers and microphase-segregating copolymers. Ultrathin barrier layers are critical to combine target selectivity with high flux. Hence the scope of layer-by-layer and self-assembly of polymers as well as interfacial polymerization of standard monomers and advanced building blocks has been expanded, with the aim to obtain in situ on supports microporous materials with suited functional groups or molecular cavities. Overall, there is an increasing number of approaches which enable a precise tailoring of selectivity and boosting the flux at the same time. Hence, much higher overall separation performance compared to state-of-the-art membranes is in principle feasible.