NSF-Funded Research Drives Innovation in Tire Performance

Every time a car brakes on a slippery road or speeds down a highway, its tires perform a delicate balancing act. They need to grip the road, withstand wear and tear and remain safe over thousands of miles of driving.

Achieving all these goals at once has long challenged tire manufacturers. As the global number of cars is projected to grow to approximately 2.5 times its 2010 level by 2050, developing longer-lasting, safer and more efficient tires is becoming increasingly important.

Tad Koga, a professor in the Department of Materials Science and Chemical Engineering, is looking for answers in a place that is far too small for the human eye to see.

"Optimizing a tire is a classic but complicated problem," Koga explained. "To optimize both wet grip and fuel efficiency, you would have to change properties of materials the size of a nanometer and another the size of a micrometer at the same time. That hasn't been done."

A nanometer is equal to one-billionth of a meter. A micrometer, or a micron, is slightly bigger and is equal to one-millionth of a meter. For reference, a water molecule is only half the size of a nanometer, and some bacteria are the size of one micrometer.

His new National Science Foundation (NSF)-funded project is investigating how polymers (long molecular chains) that make up rubber interact with silica at the nanoscale. The goal is to better understand how these microscopic interactions ultimately affect tire performance.

The NSF funding follows an earlier four-year grant, providing back-to-back support for the research. The current award, which launched July 1, 2026, will run for three years.

"Professor Koga's research connects a fundamental question in materials science with a challenge that affects everyone on the road," said Anatoly Frenkel, chair of the Department of Materials Science and Chemical Engineering. "His sustained NSF support recognizes the importance of this work. By bringing together university researchers, national laboratories and industry, he is also creating outstanding opportunities for our students to help translate molecular-level discoveries into practical use."

Two PhD students are contributing to the project: Xiaoran Wang focuses on laboratory experiments, and Avi Bajaj uses computer simulations to investigate how the molecules are arranged and how they move.

Tires are made primarily of rubber, which consists of long, flexible molecular chains, along with tiny reinforcing particles such as silica. These chains can be imagined as a bowl of spaghetti, with strands that bend, move and interact with one another. The rubber and silica, however, have very different chemical characteristics.

Rubber polymers are largely non-polar and hydrophobic. Basically, they are more chemically compatible with oil-like substances. Silica is polar and hydrophilic, which means it interacts more readily with water. This makes the silica-polymer interface a critical area of research aimed at improving how silica reinforces rubber and, ultimately, tire performance.

At this interface, the two materials must interact well enough to transfer forces between them as a tire repeatedly deforms during driving. If these interactions can be better understood and controlled, researchers may discover ways to improve tire strength, durability, and efficiency without sacrificing safety. Yet the molecular-level processes that govern how rubber and silica interact - and how those interactions change over time - remain unclear.

These properties include notions such as wet grip, fuel efficiency, abrasion resistance, fatigue and more.

The problem is there is always a trade-off. Tire brands are constantly deciding whether to prioritize certain aspects: should wet grip be prioritized over fuel efficiency?

The research asks why the material behaves as it does and whether engineers can deliberately change its microscopic structure to incorporate multiple properties at once.

Understanding these concepts could lead to the development of a more robust adhesive interface between rubber and silica, which could contribute to better mechanical performance, flexibility, efficiency, and durability.

The researchers will use neutron and X-ray scattering techniques to study these interactions. Koga and his team are collaborating with Brookhaven National Laboratory and Oak Ridge National Laboratory. By measuring how X-rays and neutrons interact with the materials, the team can investigate the structures and movements of rubber molecules and silica particles at the nanoscale.

Computer simulations will complement these measurements, helping the researchers interpret their results and explore molecular behavior that is difficult to observe directly.

The researchers are also collaborating with Sumitomo Rubber Industries, a Japanese company with experience in tire technology. This partnership connects fundamental scientific research with practical challenges in tire development.

It also gives the PhD students opportunities to work across disciplines, communicate their findings, and learn how scientific discoveries can contribute to industrial innovation.

For Koga, the overarching goal is to make tires last longer and work better without compromising safety. "Instead of someone having to change their tires every five years, imagine if we could extend that to 10 or more years," he said.

- Salomé Davoudiasl