Towards a Better Understanding of Porous Membrane Transport

When introduced into the non-solvent induced phase separation process, block copolymers are capable of self-assembling into films comprised of densely-packed arrays of monodisperse cylindrical nanopores providing ideal structures for filtration membranes. In theory, aligned cylinders formed through nanostructuring of block copolymers can enable an ideal isoporous structure similar to that of track-etched membranes, while achieving high surface porosities and maintaining ease and economy of large-scale membrane fabrication. Herein, we use these materials as ideal models of ultrafiltration membrane structures to probe the validity of the advanced Convection-Diffusion-Affinity model. This structure-performance model relates solvent and solute transport to structure, accounting for hindered convection and diffusion as well as solvent/solute-membrane affinity, including the decay of solute/solvent-membrane interaction energy relative to the pore wall. Our work provides new insight into the mechanisms of porous membrane solvent/solute transport as well as potential membrane filtration performance enhancements that may be achieved with block copolymer membrane materials.