Isoporous membranes with tunable size and surface via ALD

Block copolymers (BCPs) are promising materials for many membrane applications such as ultrafiltration (UF) membranes for water treatment due to their ability to self-assemble into highly ordered structures with uniform pore size and high pore density. Typically, the pore’s size and surface interactions are controlled by the BCP chemistry. In this study, we aim to tailor the size and chemistry of BCP based UF membranes by selectively growing metal oxides inside the pores. PS-b-P4VP BCP were used to fabricate UF membranes in a process combining self-assembly with non-solvent induced phase separation (SNIPS). This results in an integral but asymmetric membrane, with ordered pores at the top of the membrane and sponge-like mechanically robust support layer at the bottom of the membrane. Sequential infiltration synthesis (SIS), a technique that enables selective growth of metal oxides inside of BCP, was used to grow AlO_x inside the P4VP domains of the membranes. By growing metal oxides in the pores, the pore size was reduced, enhancing membrane selectivity.