We recently demonstrated that cross-linked lyotropic (i.e., surfactant) liquid crystal (LLC) assemblies can be used as a new type of membrane material for molecular size-selective water nanofiltration and desalination applications. Notably, we found that ordered, 3D-nanoporous, cross-linked LLC networks with a type I bicontinuous cubic (QI) phase can be prepared from a new imidazolium-based gemini LLC monomer.  By using glycerol instead of more volatile water as the LLC-phase-forming solvent with this monomer, it was possible to solution-cast thin-film composite (TFC) QI polymer membranes for the first time. After photo-cross-linking and pre-filtration to replace the glycerol in the ionic LLC nanopores with water, TFC membranes with uniform, 0.96-nm-wide annular pores were obtained that are able to separate dissolved molecular solutes from water via molecular sieving and charge repulsion effects.  Herein, we present progress in (1) understanding salt ion effects on the filtration performance of these new membranes; (2) designing new, more easily synthesized QI-phase LLC monomers; and (3) exploring new strategies for tuning nanopore size and incorporating new functional groups in the pores.  The relative merits and technical challenges of these approaches will be discussed.

Recent advances in the design of lyotropic liquid crystal-based nanoporous polymer membranes for water purification applications

247th National Meeting (2014)

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