The researchers placed these liquid crystals into water droplets, which in turn were placed in oil, producing an emulsion. At high enough concentrations within the droplets, the liquid crystals exhibit a twisting pattern visible under an optical microscope.
At even higher concentrations, however, the liquid crystals display an even more unusual behavior: their constituent molecules stack to form columns that organize into crystal-like structures and transform the normally spherical water droplets into faceted fluid gemstones.
The research was led by postdoctoral fellow
"Our long range goal," Yodh said, "is to gain more understanding and control over this liquid crystal system in order to harness its abilities to make useful new materials. Research with this type of liquid crystal is at a stage similar to that of display liquid crystals in the early '70s. The first displays were limited until their properties were really understood."
The type of liquid crystals the researchers investigated in this study are lyotropic chromonic liquid crystals, or LCLCs. They contain organic salts commonly known as "Sunset Yellow" or "Yellow 6," a widely used food dye found in orange soda, cheese-flavored snacks and many other products.
When placed in water, individual molecules of the dye stack up like poker chips, forming microscopic rods. Then the liquid-crystal containing water drops are mixed into an oil suspension along with soap-like surfactants. With one end attracted to water and the other end repelled by it, the surfactant molecules travel to the surface of the drop once it is immersed in oil. This helps stabilize the drop into a sphere, which is the optimal shape for minimizing surface energy.
Once the droplets are in the oil emulsion, the rods interact with one another to form different kinds of aligned phases. Unlike the liquid crystals found in displays, the phases or patterns formed by lyotropic liquid crystals are dependent on their concentration. To vary LCLC concentration, the researchers started with different concentrations of the dye molecules in the droplets and permitted the concentration to increase further as water diffused out of the droplets.
At a sufficiently high level of concentration, the rods are pushed close enough together that they begin to align parallel to one another, forming what is known as a "nematic" phase. This gives the droplet a well-defined north-south axis running through its center. Rods near this axis line up in parallel, until they get to the two "poles" where the rods are not oriented with respect to one another.
Keywords for this news article include: Physics, Astronomy,
Our reports deliver fact-based news of research and discoveries from around the world. Copyright 2014, NewsRx LLC
Most Popular Stories
- Obama Administration Releases Proposal to Regulate For-Profit Colleges
- Apple, HP, Intel May Take a Hit from Slowdown in Smartphone Sales Growth
- Elizabeth Vargas' Husband Marc Cohn Addresses Rumors
- Keurig Adds Peet's coffee, Alters Starbucks deal
- Motley Crue's Nikki Sixx Marries Model Courtney Bingham
- U.S. to Relinquish Gov't Control Over Internet
- FDIC Files Lawsuit on Behalf of Banks Allegedly Hurt by Libor Scandal
- Chinese e-Commerce Giant Alibaba Gears for IPO in U.S.
- Some California Cities Seeking Water Independence
- Quiznos Files for Chapter 11