Researchers from North Carolina State University are working on developing an alternative to petroleum-based plastic films derived from crustaceans and seaweed.

Specifically, the team is combining chitosan, which is a biopolymer that is responsible for the hardness of crab shells, and agarose, which is a biopolymer derived from seaweed that is used in the making of gels, to create biopolymer composite films.

Source: North Carolina State University

According to the researchers, the new transparent films have demonstrated enhanced strength, antibacterial properties, are biodegradable and repel water. The material is being eyed for sustainable packaging films for food and consumer goods.

To avoid a previous outcome wherein the combination of chitosan and agarose resulted in gritty films lacking the appropriate strength, the North Carolina State University team reinforced the agarose films with fibrillated colloidal scale material — otherwise known as soft dendritic colloids — derived from chitosan. The chitosan micro- and nanoscale fibrils reportedly provided strength and stability to the agarose film.

"We use chitosan dendritic particles to reinforce the agarose matrix because of the compatibility of both materials leading to good mechanical properties; chitosan particles also have an opposite charge to agarose. When mixed, these charges are neutralized so the resulting materials also become more resistant to water," the researchers explained.

The team explained that the biopolymer composites are roughly four times stronger than the agarose films alone. Further, they have also demonstrated resistance to E. coli, and degraded significantly while buried underground for one month.

The team will continue to modify the film so that it is more impermeable to water and oxygen.

An article detailing the film, “Hierarchically reinforced biopolymer composite films as multifunctional plastics substitute,” appears in the journal Cell Reports Physical Science.