The Rice lab of chemist James Tour has enhanced a polymer material to make it far more impermeable to pressurized gas and far lighter than the metal in tanks now used to contain the gas.
The combination could be a boon for an auto industry under pressure to market consumer cars that use cheaper natural gas. It could also find a market in food and beverage packaging.
Tour and his colleagues at Rice and in Hungary, Slovenia and India reported their results this week in the online edition of the American Chemistry Society journal ACS Nano.
By adding modified, single-atom-thick graphene nanoribbons (GNRs) to thermoplastic polyurethane (TPU), the Rice lab made it 1,000 times harder for gas molecules to escape, Tour said. That's due to the ribbons' even dispersion through the material. Because gas molecules cannot penetrate GNRs, they are faced with a "tortuous path" to freedom, he said.
The researchers acknowledged that a solid, two-dimensional sheet of graphene might be the perfect barrier to gas, but the production of graphene in such bulk quantities is not yet practical, Tour said.
But graphene nanoribbons are already there. Tour's breakthrough "unzipping" technique for turning multiwalled carbon nanotubes into GNRs, first revealed in Nature in 2009, has been licensed for industrial production. "These are being produced in bulk, which should also make containers cheaper," he said.
The researchers led by Rice graduate student Changsheng Xiang produced thin films of the composite material by solution casting GNRs treated with hexadecane and TPU, a block copolymer of polyurethane that combines hard and soft materials. The tiny amount of treated GNRs accounted for no more than 0.5 percent of the composite's weight. But the overlapping 200- to 300-nanometer-wide ribbons dispersed so well that they were nearly as effective as large-sheet graphene in containing gas molecules. The GNRs' geometry makes them far better than graphene sheets for processing into composites, Tour said.
They tested GNR/TPU films by putting pressurized nitrogen on one side and a vacuum on the other side. For films with no GNRs, the pressure dropped to zero in about 100 seconds as nitrogen escaped into the vacuum chamber. With GNRs at 0.5 percent, the pressure didn't budge over 1,000 seconds, and it dropped only slightly over more than 18 hours.
Stress and strain tests also found that the 0.5 percent ratio was optimal for enhancing the polymer's strength.
"The idea is to increase the toughness of the tank and make it impermeable to gas," Tour said. "This becomes increasingly important as automakers think about powering cars with natural gas. Metal tanks that can handle natural gas under pressure are often much heavier than the automakers would like."
He said the material could help to solve long-standing problems in food packaging, too.
"Remember when you were a kid, you'd get a balloon and it would be wilted the next day? That's because gas molecules go through rubber or plastic," Tour said. "It took years for scientists to figure out how to make a plastic bottle for soda. Once, you couldn't get a carbonated drink in anything but a glass bottle, until they figured out how to modify plastic to contain the carbon dioxide bubbles. And even now, bottled soda goes flat after a period of months.
"Beer has a bigger problem and, in some ways, it's the reverse problem," he said. "Oxygen molecules get in through plastic and make the beer go bad." Bottles that are effectively impermeable could lead to brew that stays fresh on the shelf for far longer, Tour said.
Co-authors of the paper are Rice graduate students Daniel Hashim, Zheng Yan, Zhiwei Peng, Chih-Chau Hwang, Gedeng Ruan and Errol Samuel; Rice alumnus Paris Cox; Bostjan Genorio, a former postdoctoral researcher at Rice and now an assistant professor at the University of Ljubljana, Slovenia; Akos Kukovecz, an associate professor of chemistry, and Zóltan Kónya, a researcher, both at the University of Szeged, Hungary; Parambath Sudeep, a research scholar at Cochin University of Science and Technology, India; Rice senior faculty fellow Robert Vajtai; and Pulickel Ajayan, the Benjamin M. and Mary Greenwood Anderson Professor in Mechanical Engineering and Materials Science and of chemistry at Rice. Tour is the T.T. and W.F. Chao Chair in Chemistry as well as a professor of mechanical engineering and materials science and of computer science at Rice.
The Air Force Research Laboratory through the University Technology Corp., the Office of Naval Research MURI graphene program and the Air Force Office of Scientific Research MURI program supported the research.
Read the abstract at http://pubs.acs.org/doi/abs/10.1021/nn404843n
This news release can be found online at http://news.rice.edu/2013/10/10/tanks-graphene-rice-advances-compressed-gas-storage/
Follow Rice News and Media Relations via Twitter @RiceUNewsRelated Materials:
A close-up cross section of graphene nanoribbon-enhanced polymer shows the ribbons as white dots dispersed through the material, where they effectively block gas molecules from passing through. The material created at Rice University could be useful for storing compressed gas in a lighter, stronger vessel and for food packaging. (Credit: Changsheng Xiang/Rice University)
An electron microscope image shows graphene nanoribbons embedded in a block copolymer. The composite material created at Rice University shows promise for containing compressed natural gas and for food packaging. (Credit: Tour Group/Rice University)
Located on a 300-acre forested campus in Houston, Rice University is consistently ranked among the nation's top 20 universities by U.S. News & World Report. Rice has highly respected schools of Architecture, Business, Continuing Studies, Engineering, Humanities, Music, Natural Sciences and Social Sciences and is home to the Baker Institute for Public Policy. With 3,708 undergraduates and 2,374 graduate students, Rice's undergraduate student-to-faculty ratio is 6-to-1. Its residential college system builds close-knit communities and lifelong friendships, just one reason why Rice has been ranked No. 1 for best quality of life multiple times by the Princeton Review and No. 2 for "best value" among private universities by Kiplinger's Personal Finance. To read "What they're saying about Rice," go to http://tinyurl.com/AboutRiceU.
David Ruth | EurekAlert!
The birth of a new protein
20.10.2017 | University of Arizona
Building New Moss Factories
20.10.2017 | Albert-Ludwigs-Universität Freiburg im Breisgau
University of Maryland researchers contribute to historic detection of gravitational waves and light created by event
On August 17, 2017, at 12:41:04 UTC, scientists made the first direct observation of a merger between two neutron stars--the dense, collapsed cores that remain...
Seven new papers describe the first-ever detection of light from a gravitational wave source. The event, caused by two neutron stars colliding and merging together, was dubbed GW170817 because it sent ripples through space-time that reached Earth on 2017 August 17. Around the world, hundreds of excited astronomers mobilized quickly and were able to observe the event using numerous telescopes, providing a wealth of new data.
Previous detections of gravitational waves have all involved the merger of two black holes, a feat that won the 2017 Nobel Prize in Physics earlier this month....
Material defects in end products can quickly result in failures in many areas of industry, and have a massive impact on the safe use of their products. This is why, in the field of quality assurance, intelligent, nondestructive sensor systems play a key role. They allow testing components and parts in a rapid and cost-efficient manner without destroying the actual product or changing its surface. Experts from the Fraunhofer IZFP in Saarbrücken will be presenting two exhibits at the Blechexpo in Stuttgart from 7–10 November 2017 that allow fast, reliable, and automated characterization of materials and detection of defects (Hall 5, Booth 5306).
When quality testing uses time-consuming destructive test methods, it can result in enormous costs due to damaging or destroying the products. And given that...
Using a new cooling technique MPQ scientists succeed at observing collisions in a dense beam of cold and slow dipolar molecules.
How do chemical reactions proceed at extremely low temperatures? The answer requires the investigation of molecular samples that are cold, dense, and slow at...
Scientists from the Max Planck Institute of Quantum Optics, using high precision laser spectroscopy of atomic hydrogen, confirm the surprisingly small value of the proton radius determined from muonic hydrogen.
It was one of the breakthroughs of the year 2010: Laser spectroscopy of muonic hydrogen resulted in a value for the proton charge radius that was significantly...
17.10.2017 | Event News
10.10.2017 | Event News
10.10.2017 | Event News
20.10.2017 | Information Technology
20.10.2017 | Materials Sciences
20.10.2017 | Interdisciplinary Research