Home > Press > Under pressure at the nanoscale, polymers play by different rules
 |
Photo by L. Brian Stauffer
William P. King, a Kritzer Faculty Scholar and professor of mechanical engineering at Illinois, has discovered that at very short length scales the polymer doesn’t play by the rules. |
Abstract:
Scientists putting the squeeze on thin films of polystyrene have discovered that at very short length scales the polymer doesn't play by the rules.
From buttons to storage bins, the molding of polymers is big business. At the nanoscale, processes such as nanoimprint lithography squeeze polymers to form patterns during the manufacture of semiconductor devices, organic electronics and optics. Thin films of polymer are important in adhesives, coatings and lubricants.
Under pressure at the nanoscale, polymers play by different rules
CHAMPAIGN, IL | Posted on October 2nd, 2008
"Although applications for nanoscale polymer flow are being widely investigated, the underlying, fundamental polymer physics is not," said William P. King, a Kritzer Faculty Scholar and professor of mechanical engineering at the University of Illinois.
"Understanding the way a polymer flows during nanoscale molding or imprinting processes is essential for designing new, nanoscale manufacturing processes," said King, who also is a researcher at the university's Beckman Institute.
In a paper to be published Thursday (Oct. 2), by Science Express, the online version of the journal Science, King and collaborators at the U. of I. and Trinity College, Dublin, report polymer squeeze flow measurements made at unprecedented, short length scales.
"We found an unexpected increase in the squeeze flow of thin films when the film thickness was smaller than 100 nanometers," King said. "This seemed backwards. Normally, you would expect the polymer to become harder and harder to press into thinner films."
The effect was even more pronounced in polymers of higher molecular weight, King said. "We expected the viscosity to increase with increasing molecular weight, but we found the opposite to be true when the films were thin enough."
Film thickness and molecular entanglement was the key, King said. In thick films, polymer chains are tangled together like cooked spaghetti. However, when the polymer film starts with a smaller initial thickness, a point is reached where the polymer chains change the way they interact with their neighbors. In very thin films, the polymer chains can no longer intertwine, and become like isolated blobs. This change in entanglement decreases the viscosity and increases the lateral squeeze flow.
To make the measurements, the researchers used a modified nanoscale indentation technique, which pressed a flat "punch" into very thin films of polystyrene. The punch, which was much wider than the thickness of the film, forced the polymer to flow around it. This lateral squeeze flow governs the dynamics of polymer movement during processes such as nanoimprint nanomanufacturing.
The research is a significant step forward in the understanding of polymer deformation that is directly related to nanoscale manufacturing, King said. "Our results suggest that polymer flow during nanoscale manufacturing may be enhanced by selecting polymers of higher molecular weight."
With King, co-authors of the paper are former U. of I. postdoctoral researcher Harry Rowland, and physics professor John Pethica and physics lecturer Graham Cross, both at Trinity College.
The work was funded by the Science Foundation of Ireland, the U.S. Department of Energy, and the U.S. National Science Foundation through the U. of I.'s Center for Nanoscale Chemical-Electrical-Mechanical Manufacturing Systems.
####
For more information, please click here
Contacts:
James E. Kloeppel
Physical Sciences Editor
217-244-1073
William King
217-244-3864
Copyright © University of Illinois at Urbana-Champaign
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:
News and information
Aspen Aerogels Announces $22.5 Million Private Placement May 18th, 2013
NanoInk, Inc. Assets To Be Sold May 18th, 2013
Beautiful "flowers" self-assemble in a beaker: Elaborate nanostructures blossom from a chemical reaction perfected at Harvard May 17th, 2013
Scientists capture first direct proof of Hofstadter butterfly effect May 17th, 2013
Add boron for better batteries: Rice University theorists say graphene-boron mix shows promise for lithium-ion batteries May 17th, 2013
Thin films
Moth-Inspired Nanostructures Take the Color Out of Thin Films May 17th, 2013
New magnetic graphene may revolutionise electronics May 11th, 2013
Govt.-Legislation/Regulation/Funding/Policy
Beautiful "flowers" self-assemble in a beaker: Elaborate nanostructures blossom from a chemical reaction perfected at Harvard May 17th, 2013
Artificial Forest for Solar Water-Splitting: Berkeley Lab Researchers Report First Fully Integrated Artificial Photosynthesis Nanosystem May 17th, 2013
Moth-Inspired Nanostructures Take the Color Out of Thin Films May 17th, 2013
NIA Public Briefing: Nanotechnology and the Council of Europe May 17th, 2013
Discoveries
Beautiful "flowers" self-assemble in a beaker: Elaborate nanostructures blossom from a chemical reaction perfected at Harvard May 17th, 2013
Artificial Forest for Solar Water-Splitting: Berkeley Lab Researchers Report First Fully Integrated Artificial Photosynthesis Nanosystem May 17th, 2013
Moth-Inspired Nanostructures Take the Color Out of Thin Films May 17th, 2013
Scientists capture first direct proof of Hofstadter butterfly effect May 17th, 2013
Materials
Advancements and developments of solid-state nanopores sensors May 16th, 2013
Physicists discover a new kind of friction: Friction in the nano-world May 16th, 2013
Squishy hydrogels may be the ticket for studying biological effects of nanoparticles May 15th, 2013
Pitt Chemists Demonstrate Nanoscale Alloys So Bright They Could Have Potential Medical Applications: “Think about a particle that will not only help researchers detect cancer sooner but be used to treat the tumor, too.” May 15th, 2013
Announcements
Aspen Aerogels Announces $22.5 Million Private Placement May 18th, 2013
NanoInk, Inc. Assets To Be Sold May 18th, 2013
NIA Public Briefing: Nanotechnology and the Council of Europe May 17th, 2013
Scientists capture first direct proof of Hofstadter butterfly effect May 17th, 2013
Printing/Lithography/Inkjet
NanoInk, Inc. Assets To Be Sold May 18th, 2013
Glowing Plant Kickstarter Project Retains Digital Marketing Agency, Command Partners: Glowing Plant brings on top Charlotte-based digital marketing firm to assist in crowdfunding campaign May 16th, 2013
Interactive Printed Products – New Applications Enabled by Organic and Printed Electronics May 16th, 2013
Nanotechnology Pioneer Named 'Entrepreneur of the Year': Royal Society of Chemistry honors Chad Mirkin for commercializing innovations May 10th, 2013