Nanotechnology Now

Our NanoNews Digest Sponsors
Heifer International



Home > Press > Mix Masters: NIST Scientists Image the Molecular Structure of Polymer Blends

Typical BCARS composite image of a polyethylene blend taken at NIST showing circular polarization response. LLD polyethylene shows red in this mode, while the HD polyethylene with deuterium substituted for hydrogen is green.
Credit: NIST
Typical BCARS composite image of a polyethylene blend taken at NIST showing circular polarization response. LLD polyethylene shows red in this mode, while the HD polyethylene with deuterium substituted for hydrogen is green.

Credit: NIST

Abstract:
Using an enhanced form of "chemical microscopy" developed at the National Institute of Standards and Technology (NIST), researchers there have shown that they can peer into the structure of blended polymers, resolving details of the molecular arrangement at sub-micrometer levels.* The capability has important implications for the design of industrially important polymers like the polyethylene blends used to repair aging waterlines.

Mix Masters: NIST Scientists Image the Molecular Structure of Polymer Blends

Gaithersburg, MD | Posted on November 29th, 2012

Polyethylene is one of the most widely produced and used polymers in the world. It's used in many familiar applications—milk bottles, for instance—but the NIST research is motivated by a more critical application: water pipes. Aging water infrastructure is a significant national issue. The Environmental Protection Agency has reported that in the United States there are over 240,000 water main breaks per year, leaks wasting 1.7 trillion gallons of water per year, and costs to taxpayers of $2.6 billion per year.

Polyethylene pipes are one potential solution. They're relatively inexpensive to make and install, and they have negligible corrosion issues and a predicted service life of up to a century under ideal conditions. Unfortunately, current test standards do not address service life under field conditions, especially for fusion joints in the pipes. This uncertainty has slowed the use of large diameter polyethylene pipe.

The industry standard for polyethylene pipes is a blend of two different forms of the polymer, a medium-weight, high-density polyethylene (HDPE) and a high molecular weight "linear low-density polyethylene" (LLDPE). Combining the two, says NIST materials scientist Young Jong Lee, dramatically improves the toughness, strength and resistance to fracture of the polymer.

The problem for quantitative service-life prediction is understanding exactly why that is. Developing the necessary predictive models has been hindered by knowing just how the HDPE and LLDPE molecules blend together. They are so close chemically that X-ray or electron imaging—the usual go-to techniques for molecular structure—can't readily distinguish them.

The NIST team is using a variation of Raman spectroscopy, which can distinguish different chemical species—and measure how much of each—by analyzing the frequencies associated with the different vibrational modes of each molecule. The exact mix of these frequencies is an extremely discriminating "fingerprint" for any particular molecule without help of fluorescence labeling. Raman spectroscopy using focused laser beams has been used as a chemical microscope, able to detail the structure of complex objects by mapping the chemical composition at each point in a three-dimensional space.

The NIST instrument, called "BCARS" (broadband coherent anti-Stokes Raman scattering) microscopy, uses a pair of lasers to gather Raman data at least 10 times faster than other Raman imaging methods, a critical feature because of the vast amount of data that must be gathered to understand such highly structured blend systems.** The extra trick is to substitute deuterium ("heavy hydrogen") for hydrogen atoms in the HDPE component. The deuterium strongly shifts the Raman spectrum, making it easy to distinguish the two components. By controlling the polarization of the light, the technique provides additional details on the local crystal orientation of molecules in the polymer. The images show, for example, the formation of microscopic spherical regions of partial crystallization with the LLDPE more concentrated towards the center.

"This is a fast, three-dimensional chemical imaging technique that's particularly useful for studying microstructures of polymeric materials," says Lee. The group currently is using BCARS to find the correlation between microscopic structures with characteristics of deformation and thermal fusion on polyethylene pipes. For more on Broadband CARS microscopy, see www.nist.gov/mml/bbd/biomaterials/bcars.cfm.

* Y.J. Lee, C.R. Snyder, A.M. Forster, M.T. Cicerone and W. Wu. Imaging the molecular structure of polyethylene blends with broadband coherent Raman microscopy. ACS Macro Lett. 2012, 1, 1347-1351.DOI: dx.doi.org/10.1021/mz300546e.

** See, for example, the Oct. 2010 story, "Faster CARS, Less Damage: NIST Chemical Microscopy Shows Potential for Cell Diagnostics" at www.nist.gov/public_affairs/tech-beat/tb20101013.cfm#cars.

####

About National Institute of Standards and Technology (NIST)
The National Institute of Standards and Technology (NIST) is an agency of the U.S. Department of Commerce.

For more information, please click here

Contacts:
Michael Baum
301-975-2763

Copyright © National Institute of Standards and Technology (NIST)

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 News Press

News and information

Flexible electronics integrated with paper-thin structure for use in space January 17th, 2025

‘Brand new physics’ for next generation spintronics: Physicists discover a unique quantum behavior that offers a new way to manipulate electron-spin and magnetization to push forward cutting-edge spintronic technologies, like computing that mimics the human brain January 17th, 2025

Quantum engineers ‘squeeze’ laser frequency combs to make more sensitive gas sensors January 17th, 2025

How a milk component could eliminate one of the biggest challenges in treating cancer and other disease, including rare diseases: Nebraska startup to use nanoparticles found in milk to target therapeutics to specific cells January 17th, 2025

Laboratories

Giving batteries a longer life with the Advanced Photon Source: New research uncovers a hydrogen-centered mechanism that triggers degradation in the lithium-ion batteries that power electric vehicles September 13th, 2024

A 2D device for quantum cooling:EPFL engineers have created a device that can efficiently convert heat into electrical voltage at temperatures lower than that of outer space. The innovation could help overcome a significant obstacle to the advancement of quantum computing technol July 5th, 2024

A battery’s hopping ions remember where they’ve been: Seen in atomic detail, the seemingly smooth flow of ions through a battery’s electrolyte is surprisingly complicated February 16th, 2024

NRL discovers two-dimensional waveguides February 16th, 2024

Govt.-Legislation/Regulation/Funding/Policy

Department of Energy announces $71 million for research on quantum information science enabled discoveries in high energy physics: Projects combine theory and experiment to open new windows on the universe January 17th, 2025

Quantum engineers ‘squeeze’ laser frequency combs to make more sensitive gas sensors January 17th, 2025

Chainmail-like material could be the future of armor: First 2D mechanically interlocked polymer exhibits exceptional flexibility and strength January 17th, 2025

Researchers uncover strong light-matter interactions in quantum spin liquids: Groundbreaking experiment supported by Rice researcher reveals new insights into a mysterious phase of quantum matter December 13th, 2024

Discoveries

Autonomous AI assistant to build nanostructures: An interdisciplinary research group at TU Graz is working on constructing logic circuits through the targeted arrangement of individual molecules: Artificial intelligence should speed up the process enormously January 17th, 2025

‘Brand new physics’ for next generation spintronics: Physicists discover a unique quantum behavior that offers a new way to manipulate electron-spin and magnetization to push forward cutting-edge spintronic technologies, like computing that mimics the human brain January 17th, 2025

Quantum engineers ‘squeeze’ laser frequency combs to make more sensitive gas sensors January 17th, 2025

How a milk component could eliminate one of the biggest challenges in treating cancer and other disease, including rare diseases: Nebraska startup to use nanoparticles found in milk to target therapeutics to specific cells January 17th, 2025

Materials/Metamaterials/Magnetoresistance

Chainmail-like material could be the future of armor: First 2D mechanically interlocked polymer exhibits exceptional flexibility and strength January 17th, 2025

Enhancing transverse thermoelectric conversion performance in magnetic materials with tilted structural design: A new approach to developing practical thermoelectric technologies December 13th, 2024

FSU researchers develop new methods to generate and improve magnetism of 2D materials December 13th, 2024

New material to make next generation of electronics faster and more efficient With the increase of new technology and artificial intelligence, the demand for efficient and powerful semiconductors continues to grow November 8th, 2024

Announcements

Quantum engineers ‘squeeze’ laser frequency combs to make more sensitive gas sensors January 17th, 2025

How a milk component could eliminate one of the biggest challenges in treating cancer and other disease, including rare diseases: Nebraska startup to use nanoparticles found in milk to target therapeutics to specific cells January 17th, 2025

The National Space Society Congratulates SpaceX on Starship’s 7th Test Flight: Latest Test of the Megarocket Hoped to Demonstrate a Number of New Technologies and Systems January 17th, 2025

The National Space Society Congratulates Blue Origin on the Inaugural Flight of New Glenn: The Heavy Lift Reusable Rocket Will Open New Frontiers and Provide Healthy Competition January 17th, 2025

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