ChemMatCARS Nuggets - Materials Science

Biomimetic Polymer Membrane Leapfrogs Current Plastics, Promises Wide Application in Commercial Small Molecule Separation

Accomplishment
A new polymer membrane separates carbon dioxide from methane a few hundred times faster than current membranes, with a purity four times greater. The membrane’s structure mimics that of ion channels in cell walls: hourglass-shaped pores of a consistent size. With suitable heat treatment and the use of template molecules, the cavity size can be tailored with relative ease to different small molecules. Small-angle x-ray scattering studies at ChemMatCARS confirmed that heat treatment at higher temperatures increased the cavity size.

Artist's impression of a plastic membrane allowing carbon dioxide to move through its hourglass-shaped pores while preventing the movement of methane.

Impact
Because this membrane can be made by conventional solvent-casting methods and tailored easily to different molecules, it appears extremely promising for many industrial processes, including

• gas separation of CO₂ and methane (natural gas processing, landfill gas recovery, and enhanced oil recovery)
• chemicals production
• pharmaceutical separation
• organic batteries
• fuel cells

Because the membrane is so much faster and more efficient than current materials, significant energy and environmental savings are expected in processes where it is applied.

The many potential applications of the gas-separation membrane include fuel cells for clean cars and improved efficiency of chemical processing.

Principal Investigators: Young Moo Lee (Hanyang University, Korea), Anita J. Hill (Commonwealth Scientific and Industrial Research Organisation, Australia), Benny D. Freeman (University of Texas)
Published in: Ho Bum Park, Chul Ho Jung, Young Moo Lee, Anita J. Hill, Steven J. Pas, Stephen T. Mudie, Elizabeth Van Wagner, Benny D. Freeman, David J. Cookson, “Polymers with Cavities Tuned for Fast Selective Transport of Small Molecules and Ions,” Science 318(5848), 254-258 (2007).
Press release: "Fantastic plastic could cut CO2 emissions and purify water," CSIRO, October 12, 2007

October 2007

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