Innovations
INNOVATION: Japanese scientists develop plastic that decomposes in seawater
A team of researchers in Japan has developed a new type of plastic that decomposes rapidly in salt water without leaving behind harmful microplastics, raising hopes for a more sustainable alternative to conventional plastics.
The material, described in the Journal of the American Chemical Society, is made from plant cellulose – the most abundant organic compound on Earth – and is both strong and flexible. Scientists say it retains the durability of petroleum-based plastics but breaks down quickly in the natural environment.
Led by Takuzo Aida at the RIKEN Center for Emergent Matter Science, the research builds on previous work in which the team developed a prototype plastic that dissolved in seawater within hours. However, the earlier version lacked practical manufacturability.
The new material, dubbed CMCSP (carboxymethyl cellulose supramolecular plastic), overcomes these limitations. It uses a commercially available biodegradable wood-pulp derivative combined with a safe crosslinking agent to create a durable yet degradable polymer network.
One of the key innovations is the use of guanidinium ions, which form reversible salt bridges with the cellulose. These bridges hold the structure together but dissolve in the presence of salt, causing the plastic to decompose. A protective surface coating can prevent unintentional breakdown in humid environments.
Initially, the plastic developed was colorless, transparent, and extremely hard, but it suffered from being too brittle due to the rigidity of cellulose. The researchers needed a plasticizer – a small molecule to make the plastic more flexible while maintaining its hardness. After considerable experimentation, they found that the organic salt choline chloride, an FDA-approved food additive, worked effectively. By varying the amount of choline chloride, they were able to fine-tune the flexibility of the plastic. It can now range from a hard, glass-like material to one that is so elastic it can stretch up to 130 per cent of its original length. The plastic can also be formed into a strong yet thin film, just 0.07 mm thick.
The team claims the new material maintains several desirable properties even after modification, including transparency, ease of processing, and closed-loop recyclability. Aida said the improvements mark a transition from conceptual development to real-world application.
“Nature produces about one trillion tons of cellulose every year,” said Aida. “From this abundant natural substance, we have created a flexible yet tough plastic material that safely decomposes in the ocean.”
Plastic pollution, particularly from microplastics, has become a growing concern in recent years. Found in oceans, soil, and even human tissue, microplastics have been linked to potential adverse health effects and long-term environmental damage.
While other so-called biodegradable plastics exist, many fail to break down effectively in marine environments or take years to do so. The researchers say their new material breaks down in seawater within hours and does not leave microplastic residues.
With its use of inexpensive and widely available ingredients, the team hopes the plastic can soon be scaled up for commercial use and contribute to reducing global plastic waste.
Why This Matters: Making plastic more environmentally friendly has been the constant challenge for scientists and polymer experts. This development by the RIKEN Center represents a true light-bulb moment. It is evidence that biodegradable plastic is possible. In the first instance this has massive significance for the packaging sector. The longer term prospects with further development are truly ground-breaking. Is it not too far fetching to believe that one day we could see plastic building products such as windows that could have an in-built lifespan of rigidity and then a period of natural decomposition? Sounds too futuristic – but you just never know.
