Plant-based waterproof material could replace single-use plastics

A waterproof, plant-based material that degrades quickly in the ocean could offer a sustainable alternative to single-use plastics in cups and straws.

Transparent paperboard is, like cellophane, made from cellulose, the molecule that makes up plant cell walls. Because of the coagulant chemicals used in cellophane’s production, it hadn’t been possible until now to make it stiff, limiting it to applications such as food packaging.

Noriyuki Isobe at the Japan Agency for Marine-Earth Science and Technology in Yokosuka and his colleagues discovered that when cellulose is treated with a solution of lithium bromide, it doesn’t require a coagulant – it can simply be left to dry instead.

“We have now developed a regenerated cellulose material from this solvent system that is not only shapeable but also has the potential to serve as a sustainable alternative to conventional plastics,” says Isobe.

The researchers found that a cup made of transparent paperboard can hold just-boiled water with almost no leakage for well over 3 hours. When they added a coating made from a plant-derived fatty acid salt, the cup became completely waterproof.

The material can be made from both recycled and upcycled cellulose products such as recovered clothing. Isobe and his colleagues also tested how the material breaks down in the ocean and found that it completely degraded in 300 days in the deep sea and more quickly at shallower depths.

Bhavna Middha at the Royal Melbourne Institute of Technology in Australia says having a paper-based alternative to plastic is “not a bad thing”, but she has some reservations about this approach to tackling the waste issue.

“I would say that there should be an objection to using anything single-use unless it’s really required by people or groups that really need single-use disposable materials – for example, the medical industry,” she says.