Researchers say they have discovered a rubbery section, only a few atoms thick, on the surface of glassy resins such as polystyrene, a breakthrough that could improve the properties of such materials and develop applications for the polymers.

The US-based University of Southern Florida (USF, Tampa, Florida; www.usf.edu) says it conducted the study in conjunction with teams from compatriot Princeton University and China’s Zhejiang Sci-Tech University, and the results could provide, for example, information about how glassy polymers can adhere to each other, and insights into scratch resistance, down to the molecular level.

“This gives us the ability to understand and control how glassy polymers – plastics – behave right at their surface,” said David Simmons, associate professor of chemical, biological and materials engineering at USF. “Whether it’s a particle of dust sticking to paint, two fibers sticking together in a 3D printer, or abrasion at the surface of a pair of a plastic lens in your glasses, this microscopic layer at the surface of plastics is immensely important to how these materials perform, and now we really understand its nature for the first time.”

USF said Simmons and his collaborators made this discovery by forming “wetting ridges”, tiny ridges at the surface of a plastic, by releasing an ionic liquid droplet on PS surfaces at various temperatures. Through measurements and by zooming in to the molecular scale with supercomputer simulation models, they revealed the presence of this soft, rubbery layer and how it can be controlled.

The discovery could point to finding the “sweet spot” for important properties such as adhesion and scratch resistance, even on rigid surfaces, USF said, citing possible improvements in batteries, automobile paint and cellphone screens thanks to the research.