By Marlene Cimons, National Science Foundation
Scientists are using a new technology that cuts and stacks different polymer materials into thousands of layers a scant billionths of a meter in size to develop a range of new improved products—powerful lenses, packaging that keeps foods safer and fresher, and “tunable’’ lasers, among them—that likely will be inexpensive to make, as well as environmentally friendly.
“We have this unique process that advances the development of new materials and materials systems," says Eric Baer, director of the Center for Layered Polymeric Systems at Case Western University. “We are looking to high value-added uses.’’
The technology, known as “forced assembly,’’ creates alternating layers of two polymers, using a special melting process that allows the material to be cut and stacked in thousands of extremely thin layers of film. It is the only such operation in the academic community in the country, possibly in the world.
Such uses for these multilayered polymer films, with their ultra–thin nanoscale layers, could include energy storage devices that would result in more efficient electric cars, faster and lighter weight computers, all-electric ships and advanced weaponry, as well as new types of “fish-eye" lenses that could revolutionize telescopes, cameras and spectacles. In food packaging, for example, the technology would eliminate the use of solvents, making the process cheaper and less toxic to the environment.
The center, a National Science Foundation Science and Technology Center, is based at Case Western Reserve University, with research partnerships at the University of Texas at Austin, Fisk University in Nashville, the University of Southern Mississippi, Kent State University, Northwestern University, and the U.S. Naval Research Laboratory.
The program’s educational component includes a relationship with the Cleveland Metropolitan School District, which sends inner city high school students to Case Western Reserve to become involved in the research and to learn to operate the technology.
NSF supports the center, which began in 2006, with about $4 million annually over ten years.
Center scientists have at least 30 projects in various stages of development, several of them close to commercialization.
The “fish-eye" lens, for example, could be on the market within three years, Baer says. The lens resembles the eye of an octopus, which can focus light five times more strongly than that of a human eye. The new lens consists of hundreds of thousands of layers of plastic from two different polymers, each with a different refractive index (a measurement of the speed of light through that substance). Each film has a refractive index that differs from the next by 1 percent, resulting in a powerful new lens with the ability to focus much like the eye of the octopus.
“Fish eyes have a large refractive index, meaning they can see extremely well under water," Baer says. “We’ve copied this lens and it is very close to what is in the eye of a fish."
Researchers at the center also are developing new plastic packaging with potential applications for foods, medicines, cosmetics and electronics that can block their exposure to gases in the air, such as oxygen, nitrogen, carbon dioxide and water vapor, all of which can have a harmful impact on the quality of these products.
When the researchers produced very thin films composed of even thinner layers of commonly used polymers, they found that polyethylene oxide, a standard ingredient in the plastics industry, forms a single layer of crystals in repeating chains that line up close together in an ordered pattern. This configuration produces a 100-fold improvement in the film’s gas barrier when it is made into nanolayers.
Even better, “the process is entirely solvent-less,’’ Baer says, “making the technology very environmentally friendly. Relatively speaking, the economics of what it takes to buy and use this technology is small compared to using systems with solvents. The investments are relatively small. We are doing something that is not only better, but cheaper."
Since different products require packaging with different gas barrier properties, the researchers also are studying a variety of polymers in different nanolayer combinations.
“This should help identify a spectrum of polymers for different applications, such as improving the shelf life of food products, for pharmaceutical use, or to prevent the oxidation of electronic or metal components,’’ Baer says.
Center scientists also have used the technology to make inexpensive laser sheets, which are stretchable and can produce “tunable’’ lasers, that is, lasers with the ability to continuously change their wave length within certain limits, unlike traditional lasers. The new lasers could have widespread applications in such fields as medicine, astronomy, communication and imaging, Baer says. “It’s rare to have a tunable laser," he adds. “Most lasers don’t tune."
In addition to product development, the center is heavily invested in outreach and education with the idea of helping to create a diverse work force in the fields of science, technology, engineering and mathematics, often known by the acronym STEM.
At its partner universities, high school students recruited by the colleges, as well as undergraduates and graduate students, work on center-related projects. In Cleveland, the center cooperates with urban school districts to identify promising high school students from under-represented groups to work directly with its research teams at Case Western Reserve, where the technology is located.
The goal is for 50 percent of the students who complete the program to pursue a college degree in a STEM field. To date, all of the students who have participated are attending college, 70 percent of them in STEM related areas.
“We have had great success with these kids from the inner city," Baer says. “We’ve had 20 graduates, and every single one of them has gone on to college."