Shape-Selective Filtration Using Lamellar Block Copolymer-Based 1D Slit Membranes

The growing need for highly efficient water purification and bioseparations necessitates innovations in ultra-filtration membranes. Block copolymer (BCP) membranes have emerged as a promising player for efficient ultra-filtration due to their uniform pore sizes and sharp cut-offs. Most of the work in BCP membranes has focused on using cylindrical pores. In this work, we demonstrate novel slit-based membranes using lamellar block copolymers. The lamellar BCPs are vertically oriented in one step film casting process by neutral solvent design. The vertically oriented BCPs are converted to slit membranes using a wet etching process. These slit-shaped membranes demonstrate sharp cut-offs for solute filtration. Furthermore, we demonstrate the first example of enhanced separation of 1-D nanomaterials (nanorods) as compared to the 0-D nanomaterials (nanoparticles) using these slit-based membranes, which is facilitated by the shape similarity of 1-D nanomaterials with the nano-slits. Additionally, we show that these slit-shaped membranes show permeability of similar-sized Lysozyme and BSA proteins while retaining the IgG antibodies, thus making them highly useful for bioseparations. We believe that these slit-shaped membranes will be useful for shape-selective filtrations across a spectrum of applications.