(241b) Nanostructured Polymer Membranes with Sub-1-Nm Pores for Molecular Size Separations Via the Cross-Linking of Lyotropic Liquid Crystal Assemblies

The development of polymers with ordered, interconnected, sub-1-nm size pores for molecular size separation is presented.  These nanostructured polymers are made by cross-linking lyotropic liquid crystal (LLC) assemblies formed by polymerizable surfactants in the presence of water.  Supported LLC polymer membranes with a type I bicontinuous cubic (QI) architecture made with a 1st-generation gemini phosphonium LLC monomer possess a 3-D interconnected water pore system with a uniform pore size of ca. 0.75 nm.  These LLC membranes are able to cleanly size-exclude hydrated salt ions and a variety of small organic solutes from water (i.e., water desalination) with good permeabilities. The water desalination/nanofiltration performance of this LLC polymer membrane is superior to that of conventional nanofiltration membranes, and close to that of commercial reverse-osmosis membranes.  The relationship between the nanoscale architecture of these polymerized LLC assemblies and their separation will be discussed.  The synthesis of a new, more modular QI-phase LLC monomer platform, and the separation performance of new LLC membranes made from this monomer, will also be presented.