(Press-News.org) Chemists at Vanderbilt University have created a new class of liquid crystals with unique electrical properties that could improve the performance of digital displays used on everything from digital watches to flat panel televisions.
The achievement, which is the result of more than five years of effort, is described by Professor of Chemistry Piotr Kaszynski and graduate student Bryan Ringstrand in a pair of articles published online on Sept. 24 and Sept. 28 in the Journal of Materials Chemistry.
"We have created liquid crystals with an unprecedented electric dipole, more than twice that of existing liquid crystals," saysKaszynski.
Electric dipoles are created in molecules by the separation of positive and negative charges. The stronger the charges and the greater the distance between them, the larger the electric dipole they produce.
In liquid crystals, the electric dipole is associated with the threshold voltage: the minimum voltage at which the liquid crystal operates. Higher dipoles allow lower threshold voltages. In addition, the dipole is a key factor in how fast liquid crystals can switch between bright and dark states. At a given voltage, liquid crystals with higher dipoles switch faster than those with lower dipoles.
Commercial potential
Vanderbilt has applied for a patent on the new class of materials. Some of the companies that manufacture liquid crystals for commercial applications have expressed interest and are currently evaluating it.
"Our liquid crystals have basic properties that make them suitable for practical applications, but they must be tested for durability, lifetime and similar characteristics before they can be used in commercial products," Kaszynski says.
If it passes commercial testing, the new class of liquid crystals will be added to the complex molecular mixtures that are used in liquid crystal displays. These blends combine different types of liquid crystals and other additives that are used to fine-tune their characteristics, including viscosity, temperature range, optical properties, electrical properties and chemical stability. There are dozens of different designs for liquid crystal displays and each requires a slightly different blend.
Scientific significance
The newly discovered liquid crystals are not only important commercially but they are also important scientifically.
Since 1888 when they were discovered, scientists have discovered more than 100,000 natural and synthetic compounds that have a liquid crystal state. They have determined that one of the prerequisites for such a state is that the molecule must be shaped like either a rod or a disc. A second requirement is that it must contain both rigid and flexible parts. It takes a delicate balance of two opposing factors or forces to produce a material halfway between a crystal and a liquid. However, there is still a great deal about this unusual state that scientists do not yet understand.
For example, scientists are still trying to determine the effect that a liquid crystal's electric dipole has on the temperature at which it becomes an ordinary liquid. The current consensus has been that increasing the strength of the dipole typically raises this transition temperature. The way in which the new type of liquid crystals are synthesized allowed Kaszynski and Ringstrand to test this theory by creating pairs of liquid crystals with the same geometry but different electric dipoles and measuring their transition temperatures. They found that subtle structural differences have a much greater effect on the transition temperature than do variations in the strength of the electric dipole.
Unique "zwitterionic" structure
What distinguishes the new class of liquid crystals is its "zwitterionic" structure. Zwitterions are chemical compounds that have a total net electrical charge of zero but contain positively and negatively charged groups. The newly developed liquid crystals contain a zwitterion made up of a negatively charged inorganic portion and a positively charged organic portion. Kaszynski first got the idea of making zwitterionic liquid crystals nearly 17 years ago when he first arrived at Vanderbilt. However, a critical piece of chemistry required to do so was missing. It wasn't until 2002 when German chemists discovered the chemical procedure that made it possible for the Vanderbilt researchers to succeed in this effort.
INFORMATION:
The research was funded by a grant from the National Science Foundation.
[Note: A multimedia version of this story is available on Exploration, Vanderbilt's online research magazine, at http://www.vanderbilt.edu/exploration/stories/zwitterion.html]
New type of liquid crystal promises to improve performance of digital displays
2010-10-06
ELSE PRESS RELEASES FROM THIS DATE:
San Diego Supercomputer Center participates in first 'Census of Marine Life'
2010-10-06
After a decade of joint work involving 2,700 researchers from 80 countries, the world's scientists – as well as the general public – can now access the Census of Marine Life, which provides the first in-depth look at the more than 120,000 diverse species which inhabit our oceans.
The Census of Marine Life initiative, started in 2000, is the result of one of the largest scientific collaborations ever conducted , the result of more than 540 expeditions and 9,000 days at sea, plus more than 2,600 academic papers published during that period.
The just-released census paints ...
Fuel cells in operation: A closer look
2010-10-06
Measuring a fuel cell's overall performance is relatively easy, but measuring its components individually as they work together is a challenge. That's because one of the best experimental techniques for investigating the details of an electrochemical device while it's operating is x-ray photoelectron spectroscopy (XPS). Traditional XPS works only in a vacuum, while fuel cells need gases under pressure to function.
Now a team of scientists from the University of Maryland, the U.S. Department of Energy's Sandia National Laboratories, and DOE's Lawrence Berkeley National ...
Neuroscience research may help patients recover from brain injury
2010-10-06
New neuroscience research by life scientists from UCLA and Australia may potentially help people who have lost their ability to remember due to brain injury or disease.
By examining how we learn and store memories, these scientists have shown that the way the brain first captures and encodes a situation or event is quite different from how it processes subsequent similar events.
The study is published in the Sept. 29 edition of the online journal PLoS ONE, a publication of the Public Library of Science.
Memories are formed in the part of the brain known as the ...
AGU journal highlights -- Oct. 5, 2010
2010-10-06
The following highlights summarize research papers that have been recently published in Geophysical Research Letters (GRL), Journal of Geophysical Research-Atmospheres (JGR-D), or Water Resources Research (WRR).
1. Antarctic sea ice increase not linked to ozone hole
While sea ice extent has declined dramatically in the Arctic in recent years, it has increased slightly in the Antarctic. Some scientists have suggested that increased Antarctic sea ice extent can be explained by the ozone hole over Antarctica. Previous simulations have indicated that the ozone hole induces ...
Oldest evidence of dinosaurs found in Polish footprints
2010-10-06
The oldest evidence of the dinosaur lineage—fossilized tracks—is described this week in Proceedings of the Royal Society B. Just one or two million years after the massive Permian-Triassic extinction, an animal smaller than a house cat walked across fine mud in what is now Poland. This fossilized trackway places the very closest relatives of dinosaurs on Earth about 250 million years ago—5 to 9 million years earlier than previously described fossilized skeletal material has indicated. The paper also described the 246-million-year-old Sphingopus footprints, the oldest evidence ...
Study: Small firms need more access to credit during financial troubles
2010-10-06
CHAMPAIGN, Ill. – When the economy sours, small firms seeking credit tend to face higher costs of financing, leading them to reinvest their profits before they pay off creditors, according to research published by a University of Illinois finance expert.
Small firms, especially those considered financially constrained as a result of their size, low dividend payment or lack of bond rating, often become bogged down in debt because they "get hooked on cheap money, when they can find it" says U. of I. finance professor Murillo Campello.
"Since small firms are usually financially ...
New fisheries system will save about $20 million, Iowa State University researchers find
2010-10-06
AMES, Iowa - Some fisheries in the United States are poised to undergo major changes in the regulations used to protect fish stocks, and Iowa State University researchers have estimated that the new system will be an economic boon to the fishing industry.
Quinn Weninger and Rajesh Singh, both associate professors in economics, estimated harvesting costs under the old system and compared that to the newly proposed fishing regulations that lift many restrictions that cause inefficiency while still limiting amounts to be harvested.
Their analysis focused on the Pacific Groundfish ...
Animations show extent of marcellus shale development
2010-10-06
The pace and extent of Marcellus Shale development across Pennsylvania can be "seen" in animated maps produced by the Penn State Marcellus Center for Outreach and Research.
Based on data from the Pennsylvania Department of Environmental Protection, the animations (http://www.marcellus.psu.edu/resources/maps.php) show both the number of drilling permits issued for the Marcellus Shale target and the number of wells drilled by year from 2007 through August 2010. Although permits were issued prior to 2007, information on those permits did not include latitude and longitude.
"These ...
A thirst for excitement is hidden in your genes
2010-10-06
Sensation seeking—the urge to do exciting things—has been linked to dopamine, a chemical that carries messages in your brain. For a new study published in Psychological Science, a journal of the Association for Psychological Science, scientists analyzed genes in the dopamine system and found a group of mutations that help predict whether someone is inclined toward sensation seeking.
Sensation seeking has been linked to a range of behavior disorders, such as drug addiction. It isn't all bad, though. "Not everyone who's high on sensation seeking becomes a drug addict. They ...
UNH researcher helps identify key reproductive hormone in oldest vertebrate
2010-10-06
DURHAM, N.H. -- Looking at a hagfish – an eyeless, snot-covered, worm-like scavenger of the deep –the last thing that comes to mind is sex. Yet the reproductive functioning of these ancient vertebrates is such an enduring enigma that a gold medal was once offered to anyone who could elucidate it.
Although the prize expired, unclaimed, long ago, University of New Hampshire professor of biochemistry Stacia Sower and colleagues at two Japanese universities have identified the first reproductive hormone of the hagfish – a gonadatropin -- representing a significant step toward ...