Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

New Crystalline Structures May Open Door to Molecular Filters

17.03.2003


Imagine a mask that could allow a person to breathe the oxygen in the air without the risk of inhaling a toxic gas, bacterium or even a virus. Effectively filtering different kinds of molecules has always been difficult, but a new process by researchers at the University of Rochester may have paved the way to creating a new kind of membrane with pores so fine they can separate a mixture of gases. Industries could use these types of membranes for extracting hydrogen from other gases for fuel cells that will power the next generation of automobiles.



Mathew Yates, assistant professor of chemical engineering, is developing a new way to make molecular sieves-crystals with holes so small that they can discriminate between large and small molecules. Many such crystals exist and are used regularly in industry and laboratories, but Yates’s crystals may be able to be properly aligned and brought together into a sheet, which would dramatically expand their possible uses.

Yates has "grown" the new kind of crystals in a solution of water and oil, where droplets of water only a few billionths of an inch wide are dispersed within the oil with the aid of soap-like compounds. Molecular sieve crystals are normally produced in a simple container of water, which is filled with the right ingredients and heated to form crystals, but this produces crystals in a wide variety of sizes that are short and thick and hard to align. Gathering the crystals together with all their pores pointing in the same direction was all but impossible. Yates found that confining the reaction within the small droplets of water dispersed in oil altered the way the crystals grew-long fibers were created with tunnel-like pores.


"Long, thin fibers are much easier to align because their lengths are so different from their widths," says Yates. "That difference gives us something to work with that has been missing from other kinds of molecular sieves. You might compare it to uncooked spaghetti, which tends to align in the same direction when bundled together."

He and his colleague, graduate student Jen-Chieh Lin, are trying a number of experiments to align the fibers. One idea is to electrically charge them so they’ll stand on end like grass in a lawn, then a polymer could be poured in to hold them in that position. The team is also looking into aligning the fibers end-to-end in a thin film that may be cut and rearranged easily. Whichever way is successful, the result might be a rubber or glass-like sheet perforated with holes so small that most molecules would not be able to pass through.

"There are a wide variety of potential applications of these materials in optics, chemistry, and even computing," says Yates. "Many of these potential applications require the synthesis of a large single crystal, which is difficult to achieve. The advantage of our approach is that we may be able to assemble many small, easy to synthesize crystals together in an ordered fashion so that they behave like a single large crystal."

Currently, molecular sieves are only used to trap or confine certain molecules, not discriminately pass them along. One common application is in pellets used as drying agents with pores small enough for only water molecules. These are mixed with a substance, say a solvent, that contains some water that needs to be removed. The water molecules can fit into the pores, but the solvent molecules cannot. The molecular sieves soak up the water from the solvent, keeping it dry. A Yates-based filter could work in a similar fashion, though the filter would not "fill up" and could be used continuously. A molecular sieve membrane may then be used to purify water or other liquids.

Another possible application for a molecular-sieve membrane lies with its optical properties. The crystals can absorb small dye molecules into its pores. In some cases the dye molecules line up in a single file manner because they are confined to the small pores. When light shines on the dyed crystals, it reacts in interesting and useful ways, such as instantly doubling its frequency. A thin film of these dyed crystals could find application as optical components used in lasers or other light-based devices.

In addition to working out how to arrange the fibers into a working membrane, Yates’s team is also trying to understand the underlying chemistry that produces the fibers. The biggest puzzle is how a fiber several hundred nanometers long can grow when the bubble it initially forms in is only a few nanometers in diameter. If Yates can understand and control the crystal growth, he may open the door to producing more uniform fibers, or even fibers that line up readily once created.

This research was funded by the University of Rochester Laboratory for Laser Energetics and the Petroleum Research Foundation.

Jonathan Sherwood | EurekAlert!
Further information:
http://www.rochester.edu/pr/News/NewsReleases/scitech/yates-molecular.html
http://www.rochester.edu/

More articles from Life Sciences:

nachricht When Air is in Short Supply - Shedding light on plant stress reactions when oxygen runs short
23.03.2017 | Institut für Pflanzenbiochemie

nachricht WPI team grows heart tissue on spinach leaves
23.03.2017 | Worcester Polytechnic Institute

All articles from Life Sciences >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: Giant Magnetic Fields in the Universe

Astronomers from Bonn and Tautenburg in Thuringia (Germany) used the 100-m radio telescope at Effelsberg to observe several galaxy clusters. At the edges of these large accumulations of dark matter, stellar systems (galaxies), hot gas, and charged particles, they found magnetic fields that are exceptionally ordered over distances of many million light years. This makes them the most extended magnetic fields in the universe known so far.

The results will be published on March 22 in the journal „Astronomy & Astrophysics“.

Galaxy clusters are the largest gravitationally bound structures in the universe. With a typical extent of about 10 million light years, i.e. 100 times the...

Im Focus: Tracing down linear ubiquitination

Researchers at the Goethe University Frankfurt, together with partners from the University of Tübingen in Germany and Queen Mary University as well as Francis Crick Institute from London (UK) have developed a novel technology to decipher the secret ubiquitin code.

Ubiquitin is a small protein that can be linked to other cellular proteins, thereby controlling and modulating their functions. The attachment occurs in many...

Im Focus: Perovskite edges can be tuned for optoelectronic performance

Layered 2D material improves efficiency for solar cells and LEDs

In the eternal search for next generation high-efficiency solar cells and LEDs, scientists at Los Alamos National Laboratory and their partners are creating...

Im Focus: Polymer-coated silicon nanosheets as alternative to graphene: A perfect team for nanoelectronics

Silicon nanosheets are thin, two-dimensional layers with exceptional optoelectronic properties very similar to those of graphene. Albeit, the nanosheets are less stable. Now researchers at the Technical University of Munich (TUM) have, for the first time ever, produced a composite material combining silicon nanosheets and a polymer that is both UV-resistant and easy to process. This brings the scientists a significant step closer to industrial applications like flexible displays and photosensors.

Silicon nanosheets are thin, two-dimensional layers with exceptional optoelectronic properties very similar to those of graphene. Albeit, the nanosheets are...

Im Focus: Researchers Imitate Molecular Crowding in Cells

Enzymes behave differently in a test tube compared with the molecular scrum of a living cell. Chemists from the University of Basel have now been able to simulate these confined natural conditions in artificial vesicles for the first time. As reported in the academic journal Small, the results are offering better insight into the development of nanoreactors and artificial organelles.

Enzymes behave differently in a test tube compared with the molecular scrum of a living cell. Chemists from the University of Basel have now been able to...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

International Land Use Symposium ILUS 2017: Call for Abstracts and Registration open

20.03.2017 | Event News

CONNECT 2017: International congress on connective tissue

14.03.2017 | Event News

ICTM Conference: Turbine Construction between Big Data and Additive Manufacturing

07.03.2017 | Event News

 
Latest News

When Air is in Short Supply - Shedding light on plant stress reactions when oxygen runs short

23.03.2017 | Life Sciences

Researchers use light to remotely control curvature of plastics

23.03.2017 | Power and Electrical Engineering

Sea ice extent sinks to record lows at both poles

23.03.2017 | Earth Sciences

VideoLinks
B2B-VideoLinks
More VideoLinks >>>