Writing yesterday (May 3, 2012) in the journal Nature, an international team of researchers led by University of Wisconsin-Madison Professor of Chemical and Biological Engineering Juan J. de Pablo reports the results of a computational study that shows liquid crystals, manipulated at the smallest scale, can unexpectedly induce the molecules they interact with to self-organize in ways that could lead to entirely new classes of materials with new properties.
"From an applied perspective, once we get to very small scales, it becomes incredibly difficult to pattern the structure of materials. But here we show it is possible to use liquid crystals to spontaneously create nanoscale morphologies we didn’t know existed," says de Pablo of computer simulations that portray liquid crystals self-organizing at the molecular scale in ways that could lead to remarkable new materials with scores of technological applications.
As their name implies, liquid crystals exhibit the order of a solid crystal but flow like a liquid. Used in combination with polarizers, optical filters and electric fields, liquid crystals underlie the pixels that make sharp pictures on thin computer or television displays. Liquid crystal displays alone are a multibillion dollar industry. The technology has also been used to make ultrasensitive thermometers and has even been deployed in lasers, among other applications.
The new study modeled the behavior of thousands of rod-shaped liquid crystal molecules packed into nano-sized liquid droplets. It showed that the confined molecules self organize as the droplets are cooled. "At elevated temperatures, the droplets are disordered and the liquid is isotropic," de Pablo explains. "As you cool them down, they become ordered and form a liquid crystal phase. The liquid crystallinity within the droplets, surprisingly, induces water and other molecules at the interface of the droplets, known as surfactants, to organize into ordered nanodomains. This is a behavior that was not known."
In the absence of a liquid crystal, the molecules at the interface of the droplet adopt a homogeneous distribution. In the presence of a liquid crystal, however, they form an ordered nanostructure. "You have two things going on at the same time: confinement of the liquid crystals and an interplay of their structure with the interface of the droplet," notes de Pablo. "As you lower the temperature the liquid crystal starts to become organized and imprints that order into the surfactant itself, causing it to self assemble."
It was well known that interfaces influence the order or morphology of liquid crystals. The new study shows the opposite to be true as well.
"Now you can think of forming these ordered nanophases, controlling them through droplet size or surfactant concentration, and then decorating them to build up structures and create new classes of materials," says de Pablo.
As an example, de Pablo suggested that surfactants coupled to DNA molecules could be added to the surface of a liquid crystal droplets, which could then assemble through the hybridization of DNA. Such nanoscale engineering, he notes, could also form the basis for liquid crystal based detection of toxins, biological molecules, or viruses. A virus or protein binding to the droplet would change the way the surfactants and the liquid crystals within the droplet are organized, triggering an optical signal. Such a technology would have important uses in biosecurity, health care and biology research settings.
The new study was supported by the U.S. Department of Energy (DOE) through the Office of Basic Energy Sciences, and the U.S. National Science Foundation. In addition to de Pablo, authors of the new report include former postdoctoral fellows J.A. Moreno-Razo and E.J. Sambriski, now at the Autonomous Metropolitan University of Mexico and Delaware Valley College, respectively; Nicholas L. Abbott, of UW-Madison; and J.P. Hernández-Ortiz of the National University of Colombia.
-- Terry Devitt (608) 262-8282, firstname.lastname@example.org
Juan de Pablo | Newswise Science News
The search for dark matter widens
21.03.2018 | American Institute of Physics
Scientists have a new way to gauge the growth of nanowires
19.03.2018 | DOE/Argonne National Laboratory
In just a few weeks from now, the Chinese space station Tiangong-1 will re-enter the Earth's atmosphere where it will to a large extent burn up. It is possible that some debris will reach the Earth's surface. Tiangong-1 is orbiting the Earth uncontrolled at a speed of approx. 29,000 km/h.Currently the prognosis relating to the time of impact currently lies within a window of several days. The scientists at Fraunhofer FHR have already been monitoring Tiangong-1 for a number of weeks with their TIRA system, one of the most powerful space observation radars in the world, with a view to supporting the German Space Situational Awareness Center and the ESA with their re-entry forecasts.
Following the loss of radio contact with Tiangong-1 in 2016 and due to the low orbital height, it is now inevitable that the Chinese space station will...
Fraunhofer Institute for Organic Electronics, Electron Beam and Plasma Technology FEP, provider of research and development services for OLED lighting solutions, announces the founding of the “OLED Licht Forum” and presents latest OLED design and lighting solutions during light+building, from March 18th – 23rd, 2018 in Frankfurt a.M./Germany, at booth no. F91 in Hall 4.0.
They are united in their passion for OLED (organic light emitting diodes) lighting with all of its unique facets and application possibilities. Thus experts in...
A new scenario seeking to explain how Mars' putative oceans came and went over the last 4 billion years implies that the oceans formed several hundred million...
For the first time, an interdisciplinary team from the University of Basel has succeeded in integrating artificial organelles into the cells of live zebrafish embryos. This innovative approach using artificial organelles as cellular implants offers new potential in treating a range of diseases, as the authors report in an article published in Nature Communications.
In the cells of higher organisms, organelles such as the nucleus or mitochondria perform a range of complex functions necessary for life. In the networks of...
Animal photoreceptors capture light with photopigments. Researchers from the University of Göttingen have now discovered that these photopigments fulfill an...
19.03.2018 | Event News
16.03.2018 | Event News
13.03.2018 | Event News
21.03.2018 | Physics and Astronomy
21.03.2018 | Materials Sciences
21.03.2018 | Life Sciences