Auburn chemists unlock hidden potential in petroleum molecules

What if the sticky black substance that paves roads and seals rooftops held the key to the future of electronics and energy storage?

At Auburn University’s College of Sciences and Mathematics, researchers are uncovering the hidden potential of asphaltenes, a chemically complex class of molecules long regarded as industrial byproducts. Led by Chris Grieco, an assistant professor in the Department of Chemistry and Biochemistry, and doctoral student Ryan Spencer, the groundbreaking project, funded by the American Chemical Society’s Petroleum Research Fund (ACS PRF), is turning these dark, tar-like substances into promising materials for future technologies.

Asphaltenes are carbon-rich molecules found in petroleum-based substances like asphalt and bitumen — thick, tar-like materials used in roads and roofing that form the heaviest fraction of crude oil. Scientists have historically avoided studying them as functional materials because of their inconsistent and poorly defined structures, but Grieco and Spencer believe that complexity may hold untapped potential.

“These materials are usually thought of as having little function,” Grieco said. “But we’re trying to re-envision them as potentially useful materials in electronics, semiconductors and even energy storage.”

To study these materials, the team collects rock samples and extracts the asphaltenes, then uses laser “hole burning” spectroscopy — a technique that shines precise laser light on the samples and measures how subsets of their molecules respond to different colors of light. This helps the researchers better understand how asphaltenes behave electronically and where they might be applied in future technologies.

“Because of their structure, the way the molecules stack and how electrons spread within them, we think they might be ideal for transporting energy and charge,” Grieco explained.

Grieco’s postdoctoral research on melanin, the brown skin pigment that protects humans from UV radiation, sparked the idea for the project. Like asphaltenes, melanin is chemically complex. Using advanced laser spectroscopy, Grieco was able to optically isolate and study its substructures — a technique now being applied to petroleum-derived materials at Auburn.

To support the work, Spencer plays a key role in processing rock samples and refining techniques to extract and purify asphaltenes from natural sources, specifically from the Hartselle Sandstone formations in northwest Alabama.

“I’m in the lab, figuring out how to purify the asphaltenes and separate them from the bitumen,” Spencer said.

The rocks, collected with help from Chris Hooks of the Geological Survey of Alabama, are particularly significant. Not only are they local, but their origin provides a rare scientific advantage.

“One interesting thing about asphaltenes is that their chemical composition varies depending on where they come from,” Spencer said. “If you buy asphalt-based materials commercially, you don’t really know the origin. But with these samples, we know exactly where they came from, and that’s important for consistency in research.”

Before receiving its two-year grant from the ACS Petroleum Research Fund, the team conducted early testing using commercially available asphalt mixtures purchased from a local hardware store. Now, with dedicated support, they’re able to scale up the research and devote more time and resources to meaningful discoveries.

“The funding is critical,” Grieco said. “It allows us to buy materials, cover lab costs and support the people doing the work. Without it, this project wouldn’t be possible and so we are very grateful to the Petroleum Research Fund.”

The project is also integrated into Auburn’s outreach efforts. This fall, the team will showcase their work at Destination STEM, a campuswide event by COSAM Outreach that brings more than 900 middle school students to campus each year. At the event, students will get a firsthand look at the rock samples and learn how science connects to real-world materials — and how something as common as asphalt might lead to future innovations.

Beyond outreach, Grieco and Spencer are focused on advancing the science itself. They’re optimistic their research will uncover new properties of asphaltenes and potentially lead to important technological breakthroughs.

“We think there are still undiscovered properties within these materials,” Grieco said. “And it’s exciting to imagine how an ancient substance that’s been largely written off for years could actually be part of a more sustainable, high-tech future.”