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Web Date: October 11, 2007

Tunable Polymer Enhances Separation Membranes

Thermal rearrangement of polyimides yields bottleneck-shaped pores with improved throughput and selectivity
Department: Science & Technology
News Channels: Materials SCENE
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BOTTLENECK
Upon heating, the polyimide at left rearranges to a spatially more confining structure, which significantly improves polymer membrane separation performance.
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BOTTLENECK
Upon heating, the polyimide at left rearranges to a spatially more confining structure, which significantly improves polymer membrane separation performance.

Take a microscopic look at an average polymer membrane and you'll find a landscape riddled with channels and pores. The size and shape of those features determine how well the material filters out various ions and molecules.

Young Moo Lee of Hanyang University, Seoul, South Korea, and an international team of researchers now have developed a type of polymer membrane that provides 100 times better throughput and selectivity than do membranes made with conventional polymers (Science 2007, 318, 254). The new membrane could have applications in gas separation, organic batteries, and fuel cells.

Key to the material's performance are its uniform bottleneck-shaped pores, which are reminiscent of cellular ion channels. These slim passages let linear CO2 slide through while keeping bulkier CH4 out.

Lee's team creates the tiny structures through the rearrangement of aromatic polyimides. Upon heating, the polyimides transform into more spatially confined meta- or para-substituted phenylene-heterocyclic ring structures. The pore size can be further tailored by adding acidic dopants, such as HCl or H3PO4.

 
Chemical & Engineering News
ISSN 0009-2347
Copyright © American Chemical Society

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