The barrier to finding viable sustainable flexible packaging — made from renewable sources — that can replace conventional plastics is the barrier.

For broad applicability, developers must engineer films that effectively block moisture and oxygen — essential for protecting food, pharmaceuticals, and sensitive electronics.

Researchers at the Georgia Institute of Technology have developed a bio-based film made from natural ingredients found in plants, mushrooms, and food waste that blocks moisture and oxygen as effectively as conventional plastics. Their findings were recently published in ACS Applied Polymer Materials.

“We’re using materials that are already abundant in nature and degrade there to produce packaging that won’t pollute the environment for hundreds or even thousands of years,” said Carson Meredith, a professor in Georgia Tech’s School of Chemical and Biomolecular Engineering (ChBE) and executive director of the Renewable Bioproducts Institute. “Our films, composed of biodegradable components, rival or exceed the performance of conventional plastics in keeping food fresh and safe.”

Meredith’s research team has worked for more than a decade to develop environmentally friendly oxygen and water barriers for packaging. While earlier research using biopolymers showed promise, high humidity continued to weaken the barrier properties.

Meredith and collaborators found a solution using a blend of these natural ingredients — cellulose (which gives plants their structure), chitosan (derived from crustacean-based food waste or mushrooms), and citric acid (from citrus fruits).

“By crosslinking these materials and adding a heat treatment, we created a thin film that reduced both moisture and oxygen transmission, even in hot, humid conditions simulating the tropics,” said lead author Yang Lu, a former postdoctoral researcher in ChBE at GT.

The barrier technology developed by the researchers consists of three primary components: A carbohydrate polymer for structure, a plasticizer to maintain flexibility, and a water-repelling additive to resist moisture. When cast into thin films, these ingredients self-organize at the molecular level to form a dense, ordered structure that resists swelling or softening under high humidity.

Even at 80% relative humidity, the films showed extremely low oxygen permeability and water vapor transmission, matching or outperforming common plastics such as polyethylene terephthalate (PET) and polyethylene vinyl alcohol (EVOH).

“Our approach creates barriers that are not only renewable, but also mechanically robust, offering a promising alternative to conventional plastics in packaging applications,” said Natalie Stingelin, professor and chair of Georgia Tech’s School of Materials Science and Engineering (MSE) and a professor in ChBE.

The technology is currently patent pending. 

The research was supported by Mars Inc., Georgia Tech’s Renewable Bioproducts Institute, and the US Department of Defense through the National Defense Science and Engineering Graduate Fellowship Program. Eric Klingenberg, a co-author of the study, is an employee of Mars, a manufacturer of packaged foods.