Highly Selective Vertically Aligned Nanopores in Sustainably Derived Polymer Membranes by Molecular Templating

We describe a combination of molecular templating and directed self-assembly to realize highly selective vertically aligned nanopores in polymer membranes using sustainably derived materials. The approach exploits a structure-directing molecule to template the assembly of plant-derived fatty acids into highly ordered columnar mesophases. Directed self-assembly using physical confinement and magnetic fields provides vertical alignment of the columnar nanostructures in large area (several cm²) thin films. Chemically cross-linking the mesophase with added conventional vinyl comonomers and removing the molecular template results in a mechanically robust polymer film with vertically aligned 1.2-1.5 nm diameter nanopores with a large specific surface area of ∼670 m²/g. The nanoporous polymer films display exceptional size and charge selectivity as demonstrated by adsorption experiments using model penetrant molecules. These materials have significant potential to function as high-performance nanofiltration membranes and as nanoporous thin films for high-density lithographic pattern transfer. The scalability of the fabrication process suggests that practical applications can be reasonably anticipated.