Nav: Home

Novel 3-in-1 'Rheo-Raman' microscope enables interconnected studies of soft materials

October 04, 2016

An innovative three-in-one instrument that allows scientists to correlate the flowability of soft "gooey" materials such as gels, molten polymers and biological fluids with their underlying microstructure and composition has been developed by scientists from the National Institute of Standards and Technology (NIST) and Thermo Fisher Scientific.

Simultaneous measurements yield a clearer picture of how structural make-up and flow behavior during processing dictate the macroscopic properties--such as strength, hardness, or electrical conductivity--that make so-called soft materials desirable for certain products or applications.

A novel combination of off-the-shelf instruments, the new research tool--called the rheo-Raman microscope--integrates:
  • a Raman spectrometer, which shines a laser on the sample and measures the tiny portion of scattered light that reveals vibrational energy levels of molecules in the sample, providing the equivalent of molecular fingerprints showing how atoms are arranged;

  • a rotational rheometer to track and measure how a liquid, suspension or slurry flows in response to stress--or, put another way, the degree to which the sample deforms; and

  • an optical microscope that collects polarized light reflected from a sample to increase contrast, enabling measurements of a specimen's structural features at microscopic scales.

The new instrument is designed for "multitasking," said Anthony Kotula, a NIST materials scientist. "It allows you to trace the evolution of microstructure across a range of temperatures and to do it in one controlled experiment rather than in two or three separate ones. It provides insights that would be very difficult to obtain through measurements made one at a time."

Homing in on the flow behavior is especially important, because it is intimately coupled with the microstructure and ultimate properties, Kotula explained.

Soft materials share features of liquids and solids. They range from plastics to liquid crystal displays and from contact lenses to biopharmaceuticals. For these "in-between materials," even slight variations in processing conditions can alter internal structures and drastically change material properties, which can open the way to improved performance or entirely new technological applications.

As they report in the Review of Scientific Instruments, the team used their prototype rheo-Raman microscope to follow and measure changes before, during and after melting a cosmetic material composed of coconut and almond oils and about 10 other ingredients. They also present simultaneous "melt" measurements taken on high-density polyethylene, which is used to make plastic bottles, corrosion-resistant pipes and many other items, as liquid molecules arrange and solidify into crystals.

Both demonstrations yielded a detailed, unfolding picture of how flow behavior and other phenomena during melting and crystallization correspond to changes in the shape and arrangement of molecules due to processing conditions.

"Based on the possibilities for direct correlation between chemical, structural and mechanical properties, we expect the rheo-Raman microscope to be critically relevant to both academic and industrial interests," the researchers concluded in their article.

"The rheo-Raman microscope is a general purpose instrument with lots of potential uses," Kotula said. "At NIST, one of our first applications pertains to 3D printing. We'll use it to better understand how polymer crystallization proceeds during the layer-by-layer printing process."
A.P. Kotula, M. Meyer, F. De Vito, J. Plog, A.R. Hight Walker and K.B. Migler. The rheo-Raman microscope: Simultaneous chemical, conformational, mechanical, and microstructural measures of soft materials. Review of Scientific Instruments. October 4, 2016. DOI: 10.1063/1.4963746

National Institute of Standards and Technology (NIST)

Related Molecules Articles:

Discovery of periodic tables for molecules
Scientists at Tokyo Institute of Technology (Tokyo Tech) develop tables similar to the periodic table of elements but for molecules.
New method for imaging biological molecules
Researchers at Karolinska Institutet in Sweden have, together with colleagues from Aalto University in Finland, developed a new method for creating images of molecules in cells or tissue samples.
How two water molecules dance together
Researchers have gained new insights into how water molecules interact.
Hand-knitted molecules
Molecules are usually formed in reaction vessels or laboratory flasks.
How molecules teeter in a laser field
When molecules interact with the oscillating field of a laser, an instantaneous, time-dependent dipole is induced.
More Molecules News and Molecules Current Events

Best Science Podcasts 2019

We have hand picked the best science podcasts for 2019. Sit back and enjoy new science podcasts updated daily from your favorite science news services and scientists.
Now Playing: TED Radio Hour

Erasing The Stigma
Many of us either cope with mental illness or know someone who does. But we still have a hard time talking about it. This hour, TED speakers explore ways to push past — and even erase — the stigma. Guests include musician and comedian Jordan Raskopoulos, neuroscientist and psychiatrist Thomas Insel, psychiatrist Dixon Chibanda, anxiety and depression researcher Olivia Remes, and entrepreneur Sangu Delle.
Now Playing: Science for the People

#537 Science Journalism, Hold the Hype
Everyone's seen a piece of science getting over-exaggerated in the media. Most people would be quick to blame journalists and big media for getting in wrong. In many cases, you'd be right. But there's other sources of hype in science journalism. and one of them can be found in the humble, and little-known press release. We're talking with Chris Chambers about doing science about science journalism, and where the hype creeps in. Related links: The association between exaggeration in health related science news and academic press releases: retrospective observational study Claims of causality in health news: a randomised trial This...