Isoporous membranes as a platform to understand nanoscale transport behavior in aqueous environments

A thorough understanding of transport behavior of water and solutes through membranes is central to scientific and technological processes such as water treatment, electrochemical energy conversion, and biosensors. As the dimensions of pores shrink to the nanoscale, the larger surface-to-volume ratio of the material enhances the role of interfaces in interactions between the membrane and solutes as well as the water itself, resulting in different physicochemical properties from the bulk. Electrostatics, van der Waals forces, hydrogen bonding, and other forces between particles and walls each play an important role in transport behavior. Traditional membrane systems, however, have substantial structural and chemical heterogeneity that hinders deciphering the interplay of these contributing mechanisms. Using a nanofabrication process centered on block copolymer lithography, we fabricate nearly ideal isoporous membranes as an experimental platform to drive insights into fundamental transport processes. Through tuning pore size and surface chemistry of isoporous membranes, we explore how parameters such as pore size affect transport behavior independently from contributions from other factors.