Soft Matter: What is it?

June 23, 2014—Mayonnaise, hair gel, and most of what makes up a human body have nothing really in common. Except this: scientists classify them all as soft matter.

Soft matter is basically a classification of materials that fall somewhere between liquids and solids. Think Crazy Glue, Jell-O, or even Silly Putty. And they’re important for many reasons, says Professor of Physics and Interdisciplinary Chair in Science Jeff Urbach, who is the director of Georgetown’s Institute for Soft Matter Synthesis and Metrology.

Soft matter has many commercial applications. These materials can serve as a lubricant between two metals so that they can be coupled together in the most efficient way. They can help extract oil and natural gas from a well. And they can be used in biomedical devices that save lives. Those practical applications served as the impetus for the creation of the institute.

The institute, which draws on the expertise of Georgetown’s physics and chemistry faculty, was started with a $6.9 million construction grant from the National Institute of Standards and Technology (NIST). The goal in creating the institute was to help grow Georgetown’s reputation in the emerging field of soft matter research while also helping identify and solve critical challenges in that area, Urbach says, including measurement, characterization, and synthesis.

“We’re building on old work with new techniques and insights,” he said. “We’re able to see things we couldn’t before because of new technology.”

Soft matter is by nature fragile at some points during its processing. Because of that, it requires strict environmental controls so that factors like temperature, humidity, light, and vibration don’t negatively impact results. As such, the labs housed within the institute are outfitted with the latest technology for sensitive measurement.

The level of computational power needed by the institute is great, but it allows scientists like Urbach to measure and study material previously inaccessible without computers. Urbach points to his colleague Daniel Blair’s work with emulsions. Think oil and vinegar salad dressing—that’s exactly the emulsion he’s using.

Blair is able to measure every droplet in the emulsion to watch how it changes when it’s pushed on.

“There’s a deep understanding of material that you couldn’t see years ago,” Urbach said. “You can ask the big questions you couldn’t ask before.”

Urbach explains that work on soft matter like emulsions can have an impact on an area that we all care about—food science. If you remove the fat from say, ice cream, chocolate or margarine, how can you make it so the texture and mouthfeel are palatable to consumers? This is a question for soft matter scientists.

Jong-in Hahm, an associate professor in the Department of Chemistry, also does research that could have implications for food science. She and her team study protein absorption by polymers, or types of plastics. The example she gives is milk in a plastic bottle.

Her work also has potential relevance for the biomedical industry, particularly in the areas of implants, surgical tools, even contact lens.

Much of Hahm’s research relies on atomic force microscopy, or super high-resolution imaging.

“It allows us to sense the chemical and physical forces between the atom at the apex of the probe tip and the atom on the biomolecule,” she said.

Hahm isn’t the only scientist at the institute who gets to play with cool gadgets. Blair’s lab uses a confocal microscope and a rheometer—both high-powered imaging tools to measure things like stress distribution and material instability.

The focus on next generation measuring tools and the results they can yield is part of what makes the institute a great partner for NIST and other scientists around the globe. Plus, it makes the institute a respected training ground for future material scientists.

“We’re building with NIST a constellation of research activities that has high impact for American and international technological advancement,” Urbach said.

—Lauren Ober