Like sculpting from within: New technique builds advanced materials out of basic plastics

In a kind of addition-by-subtraction, chemists at the University of Florida have developed a technique to create highly porous materials from the ubiquitous building blocks of everyday plastics, and the end result could have applications in electronics, separations and battery manufacturing.

The trick isn’t what they add, but what they take out.

“It's like what a sculptor might do with stone, where you gradually subtract more and more until you have what you want,” said Brent Sumerlin, Ph.D., a professor of chemistry at UF and senior author of the new report. “We're sculpting from within by creating pores from inside the material, which I don't think would be possible by any method.”

These kinds of porous materials are in high demand for batteries. They also make natural filters for contaminated water. Slight tweaks would even allow electronics manufacturers to fabricate the materials required for high-density electronic or magnetic storage applications.

The work was supported in part by the Department of Energy, the National Science Foundation and the Department of Defense. Sumerlin and his team published their findings Oct. 29 in the journal ACS Central Science.

The technique rose out of Sumerlin’s previous research on breaking down plastics, an essential part in improving plastics recycling. As they discovered that different plastics break down at different temperatures, Sumerlin’s lab realized they could use that temperature difference to create brand-new materials.

In the lab, they combined the buildings blocks of Plexiglas and Styrofoam, which are usually reluctant to mix. Heated up to the right temperature, the plexiglass-like components evaporated, while the polystyrene stayed behind, creating trillions of tiny gaps smaller than even a virus.

A sample weighing just a gram managed to contain within its pores the surface area of a full-sized tennis court. And for advanced manufacturing, surface area is king.

“It’s like having a very small mesh in a screen, which is potentially good for purifying wastewater,” said Sumerlin, who has also filed a patent application for the new technique. “It also works as a high-performance membrane, which is key to many batteries.”

With much of the world’s energy going toward separating one material from another, having a new way to craft these porous filters, out of little more than plastic, may end up serving many different industries. All from the original goal of trying to better recycle plastics.

“This just shows how basic research in one area can inform new applications in a completely different area,” Sumerlin said.