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Lyotropic Liquid Crystal (LLC) Nanofiltration Membranes

Applications in biofuels and bio-process mixture separations

University of Colorado

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Lyotropic Liquid Crystal (LLC) Nanofiltration Membranes
Lyotropic Liquid Crystal (LLC) Nanofiltration Membranes

Technology Marketing SummaryUniversity of Colorado research groups led by Douglas Gin and Richard Noble have developed a novel type of filtration membrane based on the polymerization of lyotropic liquid crystals (LLCs) that contains ordered, densely packed, size-tunable pores of uniform size. These new LLC membranes have pore sizes on the order of 0.5-2 nm. The resulting size-selectivity of these membranes enables high, predictable rejection of dissolved ions (salts, in particular) from water as well as a number of organic molecular solutes. In this way, these novel membranes combine the best filtering characteristics of both RO membranes (removal of ions) and nano-filtration techniques but with additional advantageous feature not present in either type of conventional membrane.DescriptionControl of membrane pore structure is a major challenge for membrane manufacturers. Of all available technologies, only RO or dialysis polymer membranes have “pores" in the size range of these novel LLC membranes. However, RO and dialysis membranes do not have uniform pore sizes, nor are they ordered, densely packed, or size-tunable. Additionally, traditional membranes are often chemically unstable, and degrade readily upon exposure to certain chemicals.

Advantages of LLC membranes include:

-Sub-1-nanometer-scale, uniform, and tunable pore sizes
-High pore density
-Controlled pore environment
-Tunable chemistry inside the nanopores for enhanced chemical selectivity
-Capable of both size-selective and chemical-selective separation
-Reduced pressure operation (lower energy cost)
-Resistance to chemical degradation (e.g. chlorine)
-Resistance to non-specific protein fouling
BenefitsDouglas Gin’s group has refined, simplified, and reduced the cost of LLC monomer synthesis. Their proprietary monomer forms a LLC phase in the presence of water that is characterized by 3D-interconnected, ordered, monodisperse, aqueous nanopores. These pore characteristics make this material particularly suitable for water filtration. The material containing the ordered LLC can be cast into thin films and subsequently photopolymerized into a cross-linked network while retaining the desired LLC phase structure. In most cases, the LLC monomer mixture is applied to existing porous substrates to form a composite membrane after in situ polymerization.Applications and IndustriesThese novel LLC membranes have shown excellent results in water desalination, but they also have many other potential applications. Separation applications of these nanoporous LLC membranes include:

-Biofuels and bio-process mixture separations
-Water desalination/purification
-Gas separations
-Solvent regeneration
More InformationPatent Documents:
“Nanoporous, Biocontinuous Cubic Lyotropic Liquid Crystal Networks via a New Polymerizable Surfactant Platform.” Filed 1/29/2010, available under CDA.

“Lyotropic Liquid Crystal Nanofiltration Membranes.” U.S. Patent 7,604,129, issued 10/20/2009.

“Lyotropic Liquid Crystal Membranes based on Cross-linked Type I Bicontinuous Cubic Phases.” Filed 5/15/2007.
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To: Lola Underwood<>