Interconnected Nanoporous Polysulfone Membranes by Microphase Separation of Randomly End-linked Copolymer Networks

Co-continuous nanostructures have been widely studied in blends, block copolymers, interpenetrating networks (IPN), and other polymer architectures. In contrast to block copolymers where equilibrium self-assembly yields ordered co-continuous phases over only small regions of composition (~5 vol. %), microphase separation in randomly end-linked copolymer networks (RECNs) has been shown to provide a kinetically insensitive route to co-continuous nanostructures and interconnected nanoporous materials across broad ranges of composition. Previously, interconnected nanoporous polystyrene (PS) materials were realized by selective etching of polylactic acid (PLA) in co-continuous PS/PLA RECNs. However, the resulting nanoporous PS structures have proven too brittle to be applied as membranes. To overcome this, we extend the concept to an engineering polymer, polysulfone (PSU), and generate co-continuous PSU/PLA RECNs and interconnected nanoporous PSU. We demonstrate that co-continuous PSU/PLA displays better mechanical properties than co-continuous PS/PLA, and that the resulting interconnected nanoporous PSU structures offer potential for applications as nanoporous templates and membranes.