KAIST's graphene oxide discovery scales from toothbrushes to aerospace materials

Fifteen years ago, a team at South Korea's KAIST made a discovery that seemed confined to the laboratory: graphene oxide, when dispersed in water at high enough concentrations, spontaneously organized itself into a liquid-crystalline state. The thin sheets of carbon aligned in a common direction, like a scattered deck of cards suddenly facing the same way. It was elegant, precise, and at the time, mostly theoretical.

Professor Sang Ouk Kim's group in the Department of Materials Science and Engineering had identified something fundamental about how matter arranges itself. What they did not know was that this observation would eventually reach millions of people brushing their teeth each morning. The discovery opened a path from pure materials science into the world of consumer goods and, more recently, into the kinds of advanced materials that aerospace engineers and electric vehicle manufacturers have been searching for.

The breakthrough lay in solving a practical problem. Graphene itself—a single layer of carbon atoms in a honeycomb pattern—is remarkably strong and conducts heat and electricity with ease. But it does not dissolve well in water, making it difficult to process into usable forms. Graphene oxide, by contrast, has oxygen functional groups attached to its surface. These groups allow it to disperse readily in water, turning it into something that can be drawn into fibers, applied as coatings, or formulated into inks. When the concentration reaches a certain threshold, the sheets spontaneously align, and that alignment becomes the key to everything that follows.

Once researchers worldwide understood what KAIST had found, they began developing methods to spin these aligned sheets into fibers. The challenge was immediate and stubborn: the liquid filament would break during the drawing process, and even when it held, the graphene sheets inside remained loosely packed, full of voids and defects that weakened the final product. For years, researchers faced a hard choice: they could improve strength or thermal conductivity, but not both simultaneously.

That changed recently when researchers at Zhejiang University in China took a different approach. They dispersed graphene oxide not in plain water but in highly viscous glycerol, giving the mixture properties similar to a polymer solution. This allowed them to stretch the dispersion far more dramatically during wet spinning—what they called ultrahigh-ratio drawing. As the material stretched, the graphene oxide sheets aligned more tightly along the fiber axis, the voids closed, and the defects diminished. Heat treatment at high temperatures then caused large, aligned graphitic crystallites to grow, producing fibers that were both lightweight and exceptionally strong.

The numbers tell the story. The resulting graphene fibers achieved a tensile strength of up to 5.9 gigapascals—meaning they resist breaking under tremendous pulling force—and a thermal conductivity of up to 1,720 watts per meter per kelvin, allowing them to transfer heat with remarkable efficiency. These were not marginal improvements. They represented a genuine breakthrough in making materials that could do two difficult things at once.

But the arc of this story does not end in academic journals. KAIST's discovery has already moved into the world. Sojaechangjo Co., Ltd., a faculty startup founded by Professor Kim, commercialized an antibacterial graphene toothbrush in 2023. Since then, more than 14 million units have sold. The same technology, under the brand name GrapheneTex, was woven into the uniforms worn by the South Korean Taekwondo demonstration team at the 2024 Paris Olympics. The material has since appeared in functional golf apparel, other sportswear, and bedding as the company pursues expansion into global markets.

What lies ahead is the real test. The properties that make these graphene fibers valuable—their low weight, high strength, and efficient heat conduction—position them for use in thermal management materials for electronic devices, lightweight thermal components for electric vehicles, aerospace applications, and wearable electronics. These are not niche markets. They are the frontiers of how modern technology is being built. A discovery made in a laboratory in 2011, when the researchers were simply observing how matter organizes itself, is now becoming the material substrate of the next generation of machines.