Featured Research

from universities, journals, and other organizations

New "Lollipop" Film Promises Improved Electronics

Date:
September 21, 2001
Source:
Texas A&M University
Summary:
Spreading a spoonful of oil on a pond of water can create a thin layer called a Langmuir-Blodgett (LB) film as was first shown by Benjamin Franklin. Similar films can be used in sensor devices, electronic switches and non-linear optical materials, but such applications have been limited by the presence of a large amount of defects in the films - until now.

COLLEGE STATION, September 19 - Spreading a spoonful of oil on a pond of water can create a thin layer called a Langmuir-Blodgett (LB) film as was first shown by Benjamin Franklin. Similar films can be used in sensor devices, electronic switches and non-linear optical materials, but such applications have been limited by the presence of a large amount of defects in the films - until now.

Related Articles


In order to improve this, three teams of chemists and chemical engineers have made a nearly defect-free LB film, thus increasing the application possibilities of LB films. Results of their research are reported in the Aug. 17 issue of the journal Science.

"This is a huge improvement," says Paul S. Cremer, a Texas A&M chemist and leader of one of the teams. "We have substantially reduced the number of defects in our LB layer, pointing a pathway as to how we might start thinking about sensor devices, electrical switches and non-linear optics materials."

An LB film consists of a single layer or many layers of organic material, each layer being one-molecule thick, deposited on a solid or liquid substrate. The film created by these scientists is made of one layer of steric acid molecules.

"Each molecule has the shape of an upside down lollipop," Cremer says. "The head represents the carboxylic acid and the long chain represents the tail."

The most striking feature of these molecules is that they are amphiphilic: the head is water-soluble whereas the tail is water-insoluble.

"These molecules love water on one side and hate water on the other side," Cremer says, "but the two sides are bound, they cannot come apart."

Ideally, the molecules sit in a perfect lattice next to each other throughout the whole layer. In reality - at least until this recent discovery - the molecules tended to cluster here and there, making one or more layers, and leaving holes in between the clusters.

Over the past couple of years, the three groups led respectively by Joseph A. Zasadzinski, professor of chemical engineering at the University of California, Santa Barbara, Daniel K. Schwartz, associate professor of chemical engineering at the University of Colorado, Boulder, and Cremer at Texas A&M have been trying to make a highly regular layer of steric acid molecules with the least number of detects as possible. The work began with Zasadzinski's idea of using more basic (non-acid) solutions.

"If you try to make these films in an acid solution, you get many more detects," Cremer says. "But if you use a basic solution, the carboxylic acid of every molecule loses a proton. That leaves a negative charge at the base of each molecule. Then if you bring in a cadmium ion, which is doubly positively charged, in between the molecules, it sticks there, locking the molecules in place."

Acting like glue, cadmium ions stick the bases of each molecule with its neighbor. The molecules cannot escape from each other nor can they jump onto each other to form more layers.

"We are locking the lollipop heads together," Cremer says, "so we can have only one layer all the way along the surface without big holes or the wrong number of layers in some places on the surface."

Cremer notes that scientists could have predicted such result many years ago, but they would not have had the techniques to prove it. They would also had to have the right basic (non-acid) solution, to consider an LB film made of steric acids, and to choose cadmium as the "stiffening" agent. (Calcium and magnesium, for example, are also doubly charged, he notes, but they do not have quite the right properties.)

Cremer adds that though this achievement is unprecedented, it is only one way to make a nearly-defect free LB layer.

"Our LB film is the best ordered among all other known LB films," he says, "but this is one way of doing it. We have not solved all the problems yet."


Story Source:

The above story is based on materials provided by Texas A&M University. Note: Materials may be edited for content and length.


Cite This Page:

Texas A&M University. "New "Lollipop" Film Promises Improved Electronics." ScienceDaily. ScienceDaily, 21 September 2001. <www.sciencedaily.com/releases/2001/09/010920072106.htm>.
Texas A&M University. (2001, September 21). New "Lollipop" Film Promises Improved Electronics. ScienceDaily. Retrieved March 6, 2015 from www.sciencedaily.com/releases/2001/09/010920072106.htm
Texas A&M University. "New "Lollipop" Film Promises Improved Electronics." ScienceDaily. www.sciencedaily.com/releases/2001/09/010920072106.htm (accessed March 6, 2015).

Share This


More From ScienceDaily



More Matter & Energy News

Friday, March 6, 2015

Featured Research

from universities, journals, and other organizations


Featured Videos

from AP, Reuters, AFP, and other news services

Driverless Budii Gives the Wheel Feel

Driverless Budii Gives the Wheel Feel

Reuters - Business Video Online (Mar. 6, 2015) The Rinspeed Budii Concept car is creating a driverless stir at this year&apos;s Geneva car show. It&apos;s an all-electric autonomous vehicle with a difference. Ciara Lee reports. Video provided by Reuters
Powered by NewsLook.com
Star Wars Inspires Mobile Holograms

Star Wars Inspires Mobile Holograms

Reuters - Business Video Online (Mar. 6, 2015) 3D holograms could soon be coming to your mobile phone. Inspired by the famous Princess Leia hologram from Star Wars, a U.S. company is showcasing a prototype display at the Mobile World Congress at Barcelona and says it could be used for real-time video calls. Ivor Bennett reports Video provided by Reuters
Powered by NewsLook.com
Game Makers Lured Into Virtual Worlds

Game Makers Lured Into Virtual Worlds

AFP (Mar. 6, 2015) Some 25,000 people have descended upon San Francisco to show off the latest technologies and video games at the Game Developers Conference. Developers here discuss the future of the industry. Duration: 02:20. Video provided by AFP
Powered by NewsLook.com
Gas Production Cut on Earthquake Fears

Gas Production Cut on Earthquake Fears

Reuters - Business Video Online (Mar. 5, 2015) The Dutch government has cut production at Europe&apos;s largest gas field in Groningen amid concerns over earthquakes which are damaging local churches. As Amy Pollock reports the decision - largely politically-motivated - could have big economic conseqeunces. Video provided by Reuters
Powered by NewsLook.com

Search ScienceDaily

Number of stories in archives: 140,361

Find with keyword(s):
Enter a keyword or phrase to search ScienceDaily for related topics and research stories.

Save/Print:
Share:

Breaking News:

Strange & Offbeat Stories


Space & Time

Matter & Energy

Computers & Math

In Other News

... from NewsDaily.com

Science News

Health News

Environment News

Technology News



Save/Print:
Share:

Free Subscriptions


Get the latest science news with ScienceDaily's free email newsletters, updated daily and weekly. Or view hourly updated newsfeeds in your RSS reader:

Get Social & Mobile


Keep up to date with the latest news from ScienceDaily via social networks and mobile apps:

Have Feedback?


Tell us what you think of ScienceDaily -- we welcome both positive and negative comments. Have any problems using the site? Questions?
Mobile: iPhone Android Web
Follow: Facebook Twitter Google+
Subscribe: RSS Feeds Email Newsletters
Latest Headlines Health & Medicine Mind & Brain Space & Time Matter & Energy Computers & Math Plants & Animals Earth & Climate Fossils & Ruins