Nanotechnology Now

Our NanoNews Digest Sponsors





Heifer International

Wikipedia Affiliate Button


android tablet pc

Home > Press > Researchers at Penn Add Another Tool in Their Directed Assembly Toolkit

A submerged micropost causes the surrounding liquid crystal to form a ring pattern, directing nanoparticles on the surface.
A submerged micropost causes the surrounding liquid crystal to form a ring pattern, directing nanoparticles on the surface.

Abstract:
An interdisciplinary team of University of Pennsylvania researchers has already developed a technique for controlling liquid crystals by means of physical templates and elastic energy, rather than the electromagnetic fields that manipulate them in televisions and computer monitors. They envision using this technique to direct the assembly of other materials, such as nanoparticles.

Researchers at Penn Add Another Tool in Their Directed Assembly Toolkit

Philadelphia, PA | Posted on November 12th, 2013

Now, the Penn team has added another tool to its directed assembly toolkit, developing a new kind of template for rearranging particles and a new set of patterns that can be formed with them.

The team consists of Kathleen Stebe, the School of Engineering and Applied Science's deputy dean for research and professor in Chemical and Biomolecular Engineering; Randall Kamien, professor in the School of Arts and Sciences' Department of Physics and Astronomy; and Shu Yang, professor in Engineering's departments of Materials Science and Engineering and Chemical and Biomolecular Engineering. Members of their labs also contributed to the new study, including lead author Marcello Cavallaro Jr., Mohamed Gharbi, Daniel Beller, Simon Čopar, Zheng Shi and Tobias Baumgart.

Their work was published in the Proceedings of the National Academy of Sciences.

Crystals are materials that have molecules arrayed in regular three-dimensional patterns; liquid crystals contain some but not all of these patterns, and their molecules can flow around one another and change the direction they face. This behavior allows defects, places on the surface where the molecular orientation of the liquid crystals is disrupted.

Despite their name, such defects are highly desirable. If the location of the defects can be controlled, the change in pattern or orientation can be put to use. In a liquid crystal display, for example, the crystals' orientation in different regions determines which parts of the screen are illuminated.

In an earlier study, the team had used a template consisting of microscopic posts to arrange the defects on the surface of smectic liquid crystals, a class of the material that forms layers. The position, shape and symmetry of the posts allowed the researchers to manipulate the bottom layer of these liquid crystals which in turn generated patterns of defects on the top layer that were orders of magnitude smaller than the original template.

In their new study, the researchers use nematic liquid crystal, which have less long-range order in their patterns but are the kind found in liquid crystal displays.

"These nematic structures are very reconfigurable. That's the basis of why they're good for displays," Stebe said. "Everyone knew that materials can be moved and positioned with electric and magnetic fields, but we're doing it with fields of elastic energy and showing that this technology can be used in assembling materials."

As in their previous experiments, the team started with a template consisting of microscopic posts that was then topped with the liquid crystal. In this experiment, however, instead of a pattern of defects forming only on the surface of the liquid crystal, a ring-shaped defect encircled each of the posts at their midpoints. This ring then acts like another template, directing the arrangement of patterns on the liquid crystal surface, more than 50 microns away.

"With the smectic liquid crystals," Kamien said, "the patterns of defects we could make were closely associated with the corners of the posts. With nematic liquid crystals, we can form these rings, which is a new way to tell what to go where."

"And we're showing," Yang said, "that, whether we use smectic or nematic crystals, we can use a template that directs these surface defect arrays, which can then hold things like colloids, nanoparticles or quantum dots."

Being able to control the spacing and arrangement of these secondary materials could allow for making new types of antennas, sensors or displays. The team's latest study provides a new set of shapes and patterns to work with in the directed assembly approach to making such devices.

"We're building up the toolkit of the different structures we can make via different confinements of these materials," Stebe said. "Once we have our toolkit filled out, it's going to become more readily apparent how we can make these structures dance — how we can make them rearrange themselves however we want — the next wave of applications will come."

The research was supported by the National Science Foundation through Penn's Materials Research Science and Engineering Center, the Laboratory for Research on the Structure of Matter, as well as The Mark Howard Shapiro and Anita Rae Shapiro Charitable Fund, the Kavli Institute for Theoretical Physics and the Simons Foundation.

####

For more information, please click here

Contacts:
Evan Lerner

215-573-6604

Copyright © University of Pennsylvania

If you have a comment, please Contact us.

Issuers of news releases, not 7th Wave, Inc. or Nanotechnology Now, are solely responsible for the accuracy of the content.

Bookmark:
Delicious Digg Newsvine Google Yahoo Reddit Magnoliacom Furl Facebook

Related Links

Download abstract:

Related News Press

Display technology/LEDs/SS Lighting/OLEDs

Martini Tech Inc. becomes the exclusive distributor for Yoshioka Seiko Co. porous chucks for Europe and North America July 20th, 2014

Carbodeon enables 20 percent increase in polymer thermal filler conductivity with 0.03 wt.% nanodiamond additive at a lower cost than with traditional fillers: Improved materials and processes enable nanodiamond cost reductions of up to 70 percent for electronics and LED app July 9th, 2014

'Nano-pixels' promise thin, flexible, high resolution displays July 9th, 2014

Projecting a Three-Dimensional Future: TAU researchers develop holography technology that could change the way we view the world July 9th, 2014

Molecular Nanotechnology

NIST shows ultrasonically propelled nanorods spin dizzyingly fast July 22nd, 2014

University of Illinois researchers demonstrate novel, tunable nanoantennas July 14th, 2014

With 'ribbons' of graphene, width matters: A narrow enough ribbon will transform a high-performance conductor into a semiconductor July 4th, 2014

Shrinky Dinks close the gap for nanowires July 1st, 2014

Discoveries

Iranian Scientists Produce Transparent Nanocomposite Coatings with Longer Lifetime July 24th, 2014

UCF Nanotech Spinout Developing Revolutionary Battery Technology: Power the Next Generation of Electronics with Carbon July 23rd, 2014

A Crystal Wedding in the Nanocosmos July 23rd, 2014

Nano-sized Chip "Sniffs Out" Explosives Far Better than Trained Dogs: TAU researcher's groundbreaking sensor detects miniscule concentrations of hazardous materials in the air July 23rd, 2014

Announcements

Silicene Labs Announces the Launch of Patent-Pending, 2D Materials Composite Index™ : The Initial 2D Materials Composite Index™ for Q2 2014 Is: 857.3; Founders Include World-Renowned Physicist and Seasoned Business and IP Professionals July 24th, 2014

Iranian Scientists Produce Transparent Nanocomposite Coatings with Longer Lifetime July 24th, 2014

Deadline Announced for Registration in 7th Int'l Nanotechnology Festival in Iran July 23rd, 2014

A Crystal Wedding in the Nanocosmos July 23rd, 2014

Interviews/Book Reviews/Essays/Reports/Podcasts/Journals

Iranian Scientists Produce Transparent Nanocomposite Coatings with Longer Lifetime July 24th, 2014

A Crystal Wedding in the Nanocosmos July 23rd, 2014

Nano-sized Chip "Sniffs Out" Explosives Far Better than Trained Dogs: TAU researcher's groundbreaking sensor detects miniscule concentrations of hazardous materials in the air July 23rd, 2014

Penn Study: Understanding Graphene’s Electrical Properties on an Atomic Level July 22nd, 2014

Grants/Awards/Scholarships/Gifts/Contests/Honors/Records

Hysitron is Awarded TWO R&D 100 Awards for Highly Innovative Technology Developments in the Areas of Extreme Environments and Biological Mechanical Property Testing July 23rd, 2014

Researchers create vaccine for dust-mite allergies Main Page Content: Vaccine reduced lung inflammation to allergens in lab and animal tests July 22nd, 2014

EPFL Research on the use of AFM based nanoscale IR spectroscopy for the study of single amyloid molecules wins poster competition at Swiss Physics Society meeting July 22nd, 2014

Carbyne morphs when stretched: Rice University calculations show carbon-atom chain would go metal to semiconductor July 21st, 2014

NanoNews-Digest
The latest news from around the world, FREE



  Premium Products
NanoNews-Custom
Only the news you want to read!
 Learn More
NanoTech-Transfer
University Technology Transfer & Patents
 Learn More
NanoStrategies
Full-service, expert consulting
 Learn More














ASP
Nanotechnology Now Featured Books




NNN

The Hunger Project







© Copyright 1999-2014 7th Wave, Inc. All Rights Reserved PRIVACY POLICY :: CONTACT US :: STATS :: SITE MAP :: ADVERTISE