Close to 2 million metric tons of plastic enters the oceans every year from beaches and waterways, according to The Ocean Cleanup Project. Much of that plastic is single-use beverage bottles, cups, and straws.
Researchers in Japan have now made a new paper-based material that could be an ideal replacement for those single-use plastics. The millimeter-thick paperboard reported in the journal Science Advances behaves like plastic, but only when needed. It is strong, transparent and shapeable, and it can hold boiling water, but it degrades within a year after settling on the ocean floor.
Plastic’s strength and durability is hard to beat. But those properties are exactly what make it an environmental nuisance: it lingers for hundreds of years in soils and waterways. And while biodegradable plastics or plastic alternatives exist, they often lack on performance. Soggy paper straws are an example.
Researchers from the Japan Agency for Marine-Earth Science and Technology struck a balance between performance and degradability with their new paperboard material. They start with cellulose, the molecule that makes up plant cell walls.
Besides being used to make paper, cellulose is also used to make transparent cellophane sheets. But cellophane films can only be made less than 0.05 mm thick because the chemicals used to solidify the cellulose solution don’t work with thicker sheets.
The Japanese team found a workaround to that problem. They made a thick cellulose hydrogel by dissolving cellulose in an aqueous lithium bromide solution. Drying the hydrogel gave clear cellulose sheets that were a millimeter-thick. The researchers could shape the sheets to make cups or straws.
A cup made from the transparent material could hold just-boiled water for over 3 hours with no leakage. When the researchers coated the cup with a plant-derived fatty acid salt, it became completely waterproof.
To test the degradability of the material in case of accidental release into the ocean, the researchers submerged paperboard sheets at sites located at four different ocean sites of varying depths. One was near a port at a depth of 2 meters, two were in waters around 750 and 850 meters deep, and the last one was submerged in deep ocean at a depth of over 5,550 meters.
Tests showed that the material fully decomposed in 300 days at deep ocean depths. The degradation was even faster in shallower depths because of warmer temperatures.
Source: Noriyuki Isobe et al. Fully circular shapable transparent paperboard with closed-loop recyclability and marine biodegradability across shallow to deep sea. Science Advances, 2025.
Image: ©Anthropocene Magazine
