New insights on an old material will enable design of better polymer batteries, water purification

ScienceDaily (June 19, 2011) — Designing new materials depends upon understanding the properties of today's materials. One such material, Nafion ©, is a polymer that efficiently conducts ions (a polymer electrolyte) and water through its nanostructure, making it important for many energy-related industrial applications, including in fuel cells, organic batteries, and reverse-osmosis water purification. But since Nafion was invented 50 years ago, scientists have only been able to speculate about how to build new materials because they have not been able to see details on how the molecules come together and work within Nafion.

Now, two Virginia Tech research groups have combined forces to devise a way to measure Nafion's internal structure and, in the process, have discovered how to manipulate this structure to enhance the material's applications.

The research is published in the June 19 issue of Nature Materials in the Letters article, "Linear coupling of alignment with transport in a polymer electrolyte membrane," by Jing Li, Jong Keun Park, Robert B. Moore, and Louis A. Madsen, all with the chemistry department in the College of Science and the Macromolecules and Interfaces Institute at Virginia Tech.

Nafion is made up of molecules that combine the non-stick and tough nature of Teflon with the conductive properties of an acid, such as battery acid. A network of tiny channels, nanometers in size, carries water or ions quickly through the polymer. "But, due to the irregular structure of Nafion, scientists have not been able to get reliable information about its properties using most standard analysis tools, such as transmission electron microscopy," said Madsen, assistant professor of physical, polymer, and materials chemistry.

Madsen and Moore, professor of physical and polymer chemistry; Madsen's post-doctoral associate Jing Li; and Moore's Ph.D. student Jong Keun Park, of Korea, were able to use nuclear magnetic resonance (NMR)to measure molecular motion, and a combination of NMR and X-ray scattering to measure molecular alignment within Nafion. "We were looking at water molecules inside Nafion as internal reporters of structure and efficiency of conduction," said Madsen. "The new feature we discovered is the locally aligned aggregates of polymer molecules in the material. The molecules align like strands of dry spaghetti lined up in a box. We can measure the speed (diffusion) of the water molecules and the direction they travel within those structures, which relates strongly to the alignment of the polymer molecule strands."

The researchers observed that the alignment of the channels influenced the speed and preferential direction of water motion. And a startlingly clear picture presented itself when the scientists stretched the Nafion and measured its structure and water motion.

"Stretching drastically influences the degree of alignment," said Madsen. "So the molecules move faster along the direction of the stretch, and in a very predictable way. These materials actually share some properties with liquid crystals -- molecules that line up with each other and are used in every LCD television, projector, and screen."

These relationships have not been previously recognized in a polymer electrolyte, Madsen said.

The ability to observe motion and direction, and understand what is happening within Nafion, has implications for using the material in new ways, and for designing new materials, the researchers write in the Nature Materials article. Ion-based applications could include actuator devices such as artificial muscles, organic batteries, and more energy efficient fuel cells. A water-based application would be improved reverse osmosis membranes for water purification.

Madsen and Moore started this collaborative project shortly after they arrived at Virginia Tech (Madsen in 2006, Moore in 2007), and they are furthering their work together by investigating new polymeric materials using their unique combination of analysis techniques.

"Alignment provides for a better flow of the molecules through the polymer," Madsen said.

The research is supported by Madsen's National Science Foundation Faculty Early Career Development (CAREER) Award. His research focuses on improving advanced polymers for fuel cells and reverse-osmosis water purification by combining detailed analysis of these materials with theoretical understanding. The research is also supported by the US Army Research Office under Ionic Liquids in Electro-Active Devices (ILEAD) Multidisciplinary University Research Initiative (MURI) grant.

Story Source:

The above story is reprinted (with editorial adaptations by ScienceDaily staff) from materials provided by Virginia Tech, via EurekAlert!, a service of AAAS.

Journal Reference:

Jing Li, Jong Keun Park, Robert B. Moore and Louis A. Madsen. Linear coupling of alignment with transport in a polymer electrolyte membrane. Nature Materials, June 19 2011 DOI: 10.1038/NMAT3048

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Diminutive 3-D printers to enable home manufacturing of custom objects

ScienceDaily (May 18, 2011) — A research project at the Vienna University of Technology (TU Vienna) could turn futuristic 3-D printers into affordable everyday items. Printers, which can produce three-dimensional objects have been available for years. However, at the Vienna University of Technology, a printing device has now been developed, which is much smaller, lighter and cheaper than ordinary 3-D printers. With this kind of printer, everyone could produce small, tailor-made 3-D objects at home, using building plans from the internet -- and this could save money for expensive custom-built spare parts.

Several scientific fields have to come together, to design a 3-D printer. The device was assembled by mechanical engineers in the research group of professor Jürgen Stampfl, but also the chemical research by the team of professor Robert Liska was of crucial importance: first, chemists have to determine which special kinds of synthetic material can be used for printing.

Layer for Layer

The basic principle of the 3-D printer is quite simple: The desired object is printed in a small tub filled with synthetic resin. The resin has a very special property: It hardens precisely where it is illuminated with intense beams of light. Layer for layer, the synthetic resin is irradiated at exactly the right spots. When one layer hardens, the next layer can be attached to it, until the object is completed. This method is called "additive manufacturing technology." "This way, we can even produce complicated geometrical objects with an intricate inner structure, which could never be made using casting techniques," Klaus Stadlmann explains. He developed the prototype together with Markus Hatzenbichler.

This method is not designed for large-scale production of bulk articles -- for that, there are cheaper alternatives. The great advantage of additive manufacturing is the fact that is offers the possibility to produce tailor-made, individually adjusted items. The prototype of the printer is no bigger than a carton of milk, it weighs 1.5 kilograms, and at just 1200 Euros, it was remarkably cheap. "We will continue to reduce the size of the printer, and the price will definitely decrease too, if it is produced in large quantities," Klaus Stadlmann believes.

LED-Projector for Higher Resolution

The printer's resolution is excellent: The individual layers hardened by the light beams are just a twentieth of a millimetre thick. Therefore, the printer can be used for applications which require extraordinary precision -- such as construction parts for hearing aids. Unlike previous models, the printer at TU Vienna uses light emitting diodes, with which high intensities of light can be obtained at very well-defined positions.

The research group for additive manufacturing technologies at TU Vienna is working with a variety of different 3-D techniques and materials. New materials -- such as special ceramics or polymers -- are constantly being developed for 3-D printing. 3-D objects can now even be made from eco-friendly biodegradable substances. In cooperation with biologists and physicians, the scientists could show that the artificial structures created with their 3-D printer technology are perfectly suited to serve as a scaffold that supports natural growth of bone structure in the body.

Remarkable Versatility

No matter whether it is medical parts, adjusted exactly to the patient's needs, special spare parts which otherwise would have to be shipped around half the globe, or whether it is just some kind of self-designed bling jewelery: with the versatile and cheap devices and materials developed in Vienna, highly complex 3-D objects can now be built from a variety of materials with very different mechanical, optical and thermal properties.

Story Source:

The above story is reprinted (with editorial adaptations by ScienceDaily staff) from materials provided by Vienna University of Technology, TU Vienna.

Note: If no author is given, the source is cited instead.

Disclaimer: Views expressed in this article do not necessarily reflect those of ScienceDaily or its staff.

View the original article here

Diminutive 3-D printers to enable home manufacturing of custom objects

ScienceDaily (May 18, 2011) — A research project at the Vienna University of Technology (TU Vienna) could turn futuristic 3-D printers into affordable everyday items. Printers, which can produce three-dimensional objects have been available for years. However, at the Vienna University of Technology, a printing device has now been developed, which is much smaller, lighter and cheaper than ordinary 3-D printers. With this kind of printer, everyone could produce small, tailor-made 3-D objects at home, using building plans from the internet -- and this could save money for expensive custom-built spare parts.

Several scientific fields have to come together, to design a 3-D printer. The device was assembled by mechanical engineers in the research group of professor Jürgen Stampfl, but also the chemical research by the team of professor Robert Liska was of crucial importance: first, chemists have to determine which special kinds of synthetic material can be used for printing.

Layer for Layer

The basic principle of the 3-D printer is quite simple: The desired object is printed in a small tub filled with synthetic resin. The resin has a very special property: It hardens precisely where it is illuminated with intense beams of light. Layer for layer, the synthetic resin is irradiated at exactly the right spots. When one layer hardens, the next layer can be attached to it, until the object is completed. This method is called "additive manufacturing technology." "This way, we can even produce complicated geometrical objects with an intricate inner structure, which could never be made using casting techniques," Klaus Stadlmann explains. He developed the prototype together with Markus Hatzenbichler.

This method is not designed for large-scale production of bulk articles -- for that, there are cheaper alternatives. The great advantage of additive manufacturing is the fact that is offers the possibility to produce tailor-made, individually adjusted items. The prototype of the printer is no bigger than a carton of milk, it weighs 1.5 kilograms, and at just 1200 Euros, it was remarkably cheap. "We will continue to reduce the size of the printer, and the price will definitely decrease too, if it is produced in large quantities," Klaus Stadlmann believes.

LED-Projector for Higher Resolution

The printer's resolution is excellent: The individual layers hardened by the light beams are just a twentieth of a millimetre thick. Therefore, the printer can be used for applications which require extraordinary precision -- such as construction parts for hearing aids. Unlike previous models, the printer at TU Vienna uses light emitting diodes, with which high intensities of light can be obtained at very well-defined positions.

The research group for additive manufacturing technologies at TU Vienna is working with a variety of different 3-D techniques and materials. New materials -- such as special ceramics or polymers -- are constantly being developed for 3-D printing. 3-D objects can now even be made from eco-friendly biodegradable substances. In cooperation with biologists and physicians, the scientists could show that the artificial structures created with their 3-D printer technology are perfectly suited to serve as a scaffold that supports natural growth of bone structure in the body.

Remarkable Versatility

No matter whether it is medical parts, adjusted exactly to the patient's needs, special spare parts which otherwise would have to be shipped around half the globe, or whether it is just some kind of self-designed bling jewelery: with the versatile and cheap devices and materials developed in Vienna, highly complex 3-D objects can now be built from a variety of materials with very different mechanical, optical and thermal properties.

Story Source:

The above story is reprinted (with editorial adaptations by ScienceDaily staff) from materials provided by Vienna University of Technology, TU Vienna.

Note: If no author is given, the source is cited instead.

Disclaimer: Views expressed in this article do not necessarily reflect those of ScienceDaily or its staff.

View the original article here