Scientists Make Glue So Strong It Can Hold 300 lbs, Withstand 400 F

Researchers at a U.S. federal lab have transformed household plastic into a type of reusable glue that has been described as one of the toughest materials ever.

Adhesives—materials that help things stick together—are commonly used in everyday life and tend to fall into two categories: strong adhesives, which provide strong sticking power but are brittle; and ductile adhesives, which have comparatively weaker sticking power but are better able to deal with stress.

Outside of nature, it is extremely rare to find a material with the characteristics of both since the features tend to be incompatible.

In the study, Tomonori Saito, a scientist at the Department of Energy's Oak Ridge National Laboratory (ORNL), and colleagues describe how they have produced a material with enhanced temperature endurance plus "unprecedented tough adhesion characteristics" that "surpass those of many existing commercial adhesives."

The scientists' approach involved using a household plastic known as SEBS, which is used in items such as handlebar grips, toothbrushes, and sports mouth guards. It is easy to make but not engineered for tough adhesion.

The team decided to modify the chemical structure of SEBS by using a process known as dynamic crosslinking. This method involved combining the SEBS materials with silica nanoparticles—used to strengthen plastics—using something called boronic esters.

The resulting material "produces a remarkably strong and tough adhesive" according to the study, and the researchers think their work could lead to the design of more tough adhesives that could be used in the car, aerospace, and construction industries.

"For this study, we upcycled a commodity thermoplastic elastomer that is commonly used in daily life," Saito told Newsweek.

"There are fundamental challenges in adding value to common plastics, to give them new uses beyond recycling. The main challenge here is that we are combining what are typically opposing properties into a single material.

"The adhesive exhibits high-temperature stability and has very broad service window at -30 to 200 Celsius (-86 to 392 Fahrenheit). In our experiments, the lap shear adhesion on an aluminum surface held around 1350 N for liquid glue and 225 N for dry adhesive, which is equivalent to 303 pounds and 50 pounds respectively. For the press release, we used the example of a square centimetre, which, based on our research results, can easily hold 300 pounds."

Another aspect of the material produced is that the crosslinking process could be reversed, described as "an unusual feature that makes [the materials] attractive for sustainable materials design."

According to an ORNL press release outlining the findings, shear tests that measure toughness by trying to detach materials with force "were off the charts" while thermal stability was enhanced to 400 degrees Fahrenheit. A square centimetre of the material was also able to hold "roughly 300 pounds," according to the lab.

But there were also limitations, such as that the glue needs to cure for one to two hours at high temperatures of around 400 degrees Fahrenheit.

The study, "Design of tough adhesive from commodity thermoplastics through dynamic crosslinking," was published in the journal Science Advances in October, 2021.

Other recent scientific studies have found that the Earth's core is cooling faster than previously thought and that the number of black holes in the universe could be a mind-boggling 40 quintillion.

Glue
Scientist working with an adhesive at the Oak Ridge National Laboratory (ORNL). Scientists there worked to upcycle a common household plastic for use as a type of glue. Carlos Jones/ORNL, U.S. Dept. of Energy