Polyester is inescapable: used in everyday items like clothes, water bottles, food packaging, and even biomedical devices, the polymer is an increasingly common choice for manufacturing.

Despite its popularity, customizing the physicochemical properties of polyester has been somewhat limited. Two Virginia Tech researchers are changing that through research recently published in the Journal of the American Chemical Society.

Rong Tong, assistant professor in the Department of Chemical Engineering in the College of Engineering, and his postdoctoral scholar, Quanyou Feng, have discovered a novel chemistry that can produce polyesters with sets of different properties.

“What that essentially means is that we can prepare polyester materials with customized macroscopic properties, such as rigidity, elasticity, and biodegradability,” Tong said.

Usually, the stiffness, stretchability, and other physical properties of polymers can be customized for different applications by varying the arrangement of a group or groups of atoms, called the sidechains, attached to the backbone of the polymer.

But sidechains on commercially available monomers, which are the molecules that bind to sidechains, are not easily introduced. This limits the repertoire of existing polyesters.

Tong’s new method uses a combination of new monomers, light, and catalysts that react to light to produce polyesters with various functional sidechains. The resulting polymer has unprecedentedly controlled stereochemistry, predictable molecular weights, and narrow molecular weight distributions.

The chemistry, known as photoredox ring-opening polymerization, has potential applications in preparing different biodegradable polyesters for plastic engineering or biomedical applications, for example.

“The polyester produced is one of the most important biodegradable polymers, considering its wide-ranging possibilities,” Tong said.

Two side-by-side photos of a chemical reaction experiment setup.
The reaction setup in both sunlight and LED light.

Polyesters are typically biocompatible and biodegradable. For example, commercial polyesters, including polylactic-co-glycolic acid and polylactic acid, can be hydrolyzed in water or decomposed in the human body over time.

This makes them useful in vivo as biomedical devices or drug delivery vehicles because they are benign to humans and animals. A few types of polyesters have been approved by the U.S. Food and Drug Administration as biodegradable sutures and implants in medical practice.

In creating this new synthetic strategy for producing polymer, Tong has made it possible to scale up the production of the polymer while also improving the consistency of the composition of the polyester.

“We’re looking forward to improving on this finding so that we can scale up the production even further and make it more affordable to produce this valuable, helpful material,” Tong said.

Virginia Tech has applied for a patent on the technique, which was also highlighted by the American Chemical Society’s popular weekly professional magazine, Chemical & Engineering News.

Written by Erica Corder

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