Nanotechnology Now

Our NanoNews Digest Sponsors
Heifer International



Home > Press > Researchers create freestanding nanoparticle films without fillers

Assistant Professor of Physics James Dickerson (left) and graduate student Saad Hasan. (Photo by Daniel DuBois)
Assistant Professor of Physics James Dickerson (left) and graduate student Saad Hasan. (Photo by Daniel DuBois)

Abstract:
Nanoparticle films are no longer a delicate matter: Vanderbilt physicists have found a way to make them strong enough so they don't disintegrate at the slightest touch.

Researchers create freestanding nanoparticle films without fillers

Posted on June 9th, 2009

In the last 25 years, ever since scientists figured out how to create nanoparticles - ultrafine particles with diameters less than 100 nanometers - they have come up with a number of different methods to mold them into thin films which have a variety of interesting potential applications ranging from semiconductor fabrication to drug delivery, solid state lighting to flexible television and computer displays.

Until now these films have had a common problem: lack of cohesion. Nanoparticles typically consist of an inorganic core coated with a thin layer of organic molecules. These particles are not very sticky so they don't form coherent thin films unless they are encapsulated in a polymer coating or mixed with molecules called chemical "cross-linkers" that act like glue to stick the nanoparticles together.

"Adding this extra material can complicate the fabrication of nanoparticle films and make them more expensive. In addition, the added material, usually a polymer, can modify the physical properties that make these films so interesting," says James Dickerson, assistant professor of physics at Vanderbilt, who headed the research group that developed freestanding nanoparticle films without any additives.

The properties of the new films and the method that the researchers use to create them is described in the article "Sacrificial layer electrophoretic deposition of freestanding multilayered nanoparticle films" published online in the journal Chemical Communications on May 27, 2009.

"Our films are so resilient that we can pick them up with a pair of tweezers and move them around on a surface without tearing," says Dickerson. "This makes it particularly easy to put them into microelectronic devices, such as computer chips."

Dickerson considers the most straightforward applications for his films to be in semiconductor manufacturing to aid in the continued miniaturization of digital circuitry and in the production of flexible television and computer screens.

A key component in the transistors in integrated circuits is an insulating layer that separates the gate, which turns current flow on and off, from the channel through which the current flows. Traditionally, semiconductor manufacturers have used silicon dioxide for this purpose. As transistors have shrunk, however, they have been forced to make this layer thinner and thinner until they reached the point where electrons leak through and sap the power from the device. This has led semiconductor manufacturers to retool their process to use "high-k" dielectric materials, such as hafnium oxide, because they have much higher electrical resistance.

"We have made high-k nanoparticle films that could be cheaper and more effective than the high-k materials the manufacturers are currently using," Dickerson says.

In addition, the physicist argues that the films have properties that make them ideal for flexible television and computer screens. They are very flexible and don't show any signs of cracking when they are flexed repeatedly. They are also made using a technique called electrophoretic deposition (EPD) that is well suited for creating patterned material and is compatible with fluorescent materials that can form the red, green and blue pixels used in flat panel television screens and computer displays.

EDP is a wet method. Nanoparticles are placed in a solution along with a pair of electrodes. When an electric current is applied, it creates an electrical field in the liquid that attracts the nanoparticles, which coat the electrodes. Using colloids, mixtures with particles 10 to 1,000 times larger than nanoparticles, EDP is widely used to apply coatings to complex metal parts such as automobile bodies, prosthetic devices, appliances and beverage containers. It is only recently that researchers like Dickerson have begun applying the technique to nanoparticles.

"The science of colloidal EDP is well known but the particles are substantially larger than the solvent molecules. Many nanoparticles, however, are about the same size as the solvent molecules, which makes the process considerably more complicated and difficult to control," Dickerson explains.

To get the method to work, in fact, Dickerson and his colleagues had to invent a new form of EDP, which they call sacrificial layer electrophoretic deposition. They added a spun-cast layer of polymer to the electrodes that serves as a pattern that organizes the nanoparticles as they are deposited. Then, after the deposition process is completed, they dissolve (sacrifice) the polymer layer to free the nanoparticle film.

According to the researchers, films made in this fashion stick together because the electrical field slams the nanoparticles into the film with sufficient force to pack the particles together tightly enough to allow naturally attractive inter-particle forces to bind the particles together.

So far the Dickerson group has used the technique to make films out of two different types of nanoparticles - iron oxide and cadmium selenide - and they believe the technique can be used with a wide variety of other nanoparticles.

"The technique is liberating because you can make these films from the materials you want and use them where you want," Dickerson says.

The co-authors on the paper are graduate students Saad A. Hasan and Dustin W. Kavich. The research was funded by a grant from Vanderbilt University.

####

About Vanderbilt University
Vanderbilt University is a center for scholarly research, informed and creative teaching, and service to the community and society at large. Vanderbilt will uphold the highest standards and be a leader in the

* quest for new knowledge through scholarship,
* dissemination of knowledge through teaching and outreach,
* creative experimentation of ideas and concepts.

In pursuit of these goals, Vanderbilt values most highly

* intellectual freedom that supports open inquiry,
* equality, compassion, and excellence in all endeavors.

Contacts:
Media Contact
David F. Salisbury
(615) 322-NEWS

Copyright © Vanderbilt University

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

Multimedia Version of article

Related News Press

Physics

Finding quantum order in chaos May 17th, 2024

International research team uses wavefunction matching to solve quantum many-body problems: New approach makes calculations with realistic interactions possible May 17th, 2024

What is "time" for quantum particles? Publication by TU Darmstadt researchers in renowned journal "Science Advances" May 17th, 2024

Simulating magnetization in a Heisenberg quantum spin chain April 5th, 2024

Thin films

Utilizing palladium for addressing contact issues of buried oxide thin film transistors April 5th, 2024

Display technology/LEDs/SS Lighting/OLEDs

Utilizing palladium for addressing contact issues of buried oxide thin film transistors April 5th, 2024

Light guide plate based on perovskite nanocomposites November 3rd, 2023

Simple ballpoint pen can write custom LEDs August 11th, 2023

Novel design perovskite electrochemical cell for light-emission and light-detection May 12th, 2023

Possible Futures

Advances in priming B cell immunity against HIV pave the way to future HIV vaccines, shows quartet of new studies May 17th, 2024

International research team uses wavefunction matching to solve quantum many-body problems: New approach makes calculations with realistic interactions possible May 17th, 2024

Aston University researcher receives £1 million grant to revolutionize miniature optical devices May 17th, 2024

Gene therapy relieves back pain, repairs damaged disc in mice: Study suggests nanocarriers loaded with DNA could replace opioids May 17th, 2024

Chip Technology

Diamond glitter: A play of colors with artificial DNA crystals May 17th, 2024

Oscillating paramagnetic Meissner effect and Berezinskii-Kosterlitz-Thouless transition in cuprate superconductor May 17th, 2024

Discovery points path to flash-like memory for storing qubits: Rice find could hasten development of nonvolatile quantum memory April 5th, 2024

Utilizing palladium for addressing contact issues of buried oxide thin film transistors April 5th, 2024

Nanomedicine

Virginia Tech physicists propose path to faster, more flexible robots: Virginia Tech physicists revealed a microscopic phenomenon that could greatly improve the performance of soft devices, such as agile flexible robots or microscopic capsules for drug delivery May 17th, 2024

Diamond glitter: A play of colors with artificial DNA crystals May 17th, 2024

Advances in priming B cell immunity against HIV pave the way to future HIV vaccines, shows quartet of new studies May 17th, 2024

New micromaterial releases nanoparticles that selectively destroy cancer cells April 5th, 2024

Nanoelectronics

Interdisciplinary: Rice team tackles the future of semiconductors Multiferroics could be the key to ultralow-energy computing October 6th, 2023

Key element for a scalable quantum computer: Physicists from Forschungszentrum Jülich and RWTH Aachen University demonstrate electron transport on a quantum chip September 23rd, 2022

Reduced power consumption in semiconductor devices September 23rd, 2022

Atomic level deposition to extend Moore’s law and beyond July 15th, 2022

Discoveries

Virginia Tech physicists propose path to faster, more flexible robots: Virginia Tech physicists revealed a microscopic phenomenon that could greatly improve the performance of soft devices, such as agile flexible robots or microscopic capsules for drug delivery May 17th, 2024

Diamond glitter: A play of colors with artificial DNA crystals May 17th, 2024

Finding quantum order in chaos May 17th, 2024

Advances in priming B cell immunity against HIV pave the way to future HIV vaccines, shows quartet of new studies May 17th, 2024

Announcements

Virginia Tech physicists propose path to faster, more flexible robots: Virginia Tech physicists revealed a microscopic phenomenon that could greatly improve the performance of soft devices, such as agile flexible robots or microscopic capsules for drug delivery May 17th, 2024

Diamond glitter: A play of colors with artificial DNA crystals May 17th, 2024

Finding quantum order in chaos May 17th, 2024

Oscillating paramagnetic Meissner effect and Berezinskii-Kosterlitz-Thouless transition in cuprate superconductor May 17th, 2024

Nanobiotechnology

Diamond glitter: A play of colors with artificial DNA crystals May 17th, 2024

Advances in priming B cell immunity against HIV pave the way to future HIV vaccines, shows quartet of new studies May 17th, 2024

New micromaterial releases nanoparticles that selectively destroy cancer cells April 5th, 2024

Good as gold - improving infectious disease testing with gold nanoparticles April 5th, 2024

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




  Premium Products
NanoNews-Custom
Only the news you want to read!
 Learn More
NanoStrategies
Full-service, expert consulting
 Learn More











ASP
Nanotechnology Now Featured Books




NNN

The Hunger Project