For millions of people, grabbing a takeaway coffee is a daily ritual. But hidden inside that familiar paper cup is a thin plastic lining that helps prevent leaks while creating an environmental problem. These coatings, typically made from fossil fuel-based plastics, can complicate recycling and potentially shed tiny particles into hot drinks. Now, researchers at the University of Waterloo have developed a plant-based alternative that could make disposable coffee cups safer, more sustainable and easier to recycle.

The innovation centres on a protective coating made from cellulose acetate reinforced with cellulose nanocrystals, both derived from plants. Unlike conventional plastic liners, which can be difficult to separate from paper during recycling, the new material shares the same cellulose-based foundation as the cup itself. This could simplify recycling while reducing dependence on petroleum-derived plastics that may remain in the environment for hundreds of years. The researchers believe their approach offers a promising way to rethink everyday disposable packaging.

Laboratory tests revealed another potential advantage. When conventional plastic-lined cups were exposed to challenging conditions, their surfaces showed signs of deterioration and released particles, raising concerns about possible microplastic contamination. The cellulose-based coating, by contrast, remained largely intact under comparable conditions. “Learning how easily some plastic liners can shed particles was eye-opening,” said Dr. Shirley Tang, a chemistry professor at Waterloo. She added that developing a high-performance coating without conventional plastics opens the door to numerous applications.

Durability was a major focus of the research. The new coating withstood prolonged exposure to boiling water, cooking oil and various solvents while maintaining its protective properties. Remarkably, it also performed well when applied to lightweight paper, including ordinary brown paper towels. This suggests manufacturers might eventually produce sturdy, leak-resistant cups using considerably less paper, potentially reducing both manufacturing costs and the amount of material discarded after use.

“The coating allowed us to use much thinner paper while still achieving the durability needed for beverage containers,” said Dr. Sayan Ganguly, a research associate in Waterloo’s Tang Nanotechnology Lab. He explained that reducing paper consumption without sacrificing performance could lower production expenses, with possible savings for consumers. The discovery has an unexpected origin: the team initially investigated lightweight, renewable materials for aviation applications before recognising that the same technology might work as a protective barrier for everyday paper products.

Although the technology remains a research development rather than a commercially available replacement, its potential extends well beyond takeaway coffee. Food containers, wrapping materials and other disposable packaging could benefit from similar cellulose-based coatings as businesses seek alternatives to conventional plastics. Questions about large-scale manufacturing, cost competitiveness and recycling performance still need to be addressed. Nevertheless, the research offers an encouraging glimpse of a future in which enjoying a morning coffee might leave behind fewer persistent plastics, without compromising convenience.

More information: Sayan Ganguly et al, A High-Temperature-Resilient All-Cellulose Barrier for Next-Generation Beverage Packaging, ACS Sustainable Chemistry & Engineering. DOI: 10.1021/acssuschemeng.6c03064

Journal information: ACS Sustainable Chemistry & Engineering Provided by University of Waterloo