researchers develop recyclable plastic that fully dissolves in the sea

Date
2025.03.20
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Researchers develop recyclable plastic that fully dissolves in the sea

‘Desalting’ helps produce ocean-degradable material

Researchers led by Takuzo Aida at the RIKEN Center for Emergent Matter Science (CEMS) in Japan develop a durable and recyclable plastic that fully dissolves in the sea. It doesn’t leave microplastic pollution in the oceans because it breaks down in the water over time. The researchers use supramolecular plastics, or polymers, with structures held together by reversible interactions. They produce these by mixing two ionic monomers: sodium hexametaphosphate, a common food additive; and guanidinium ion-based monomers, a chemical forming strong but flexible connections.

Bacteria can break down both of these materials or monomers, making the recyclable plastic fully dissolvable. There’s a process called ‘desalting’ that helps the recyclable plastic dissolve in the sea. When researchers mix the two monomwers in water, they become separate. The first has a thick later that contains the structural components of the plastic. The second has a ‘watery’ later containing the salt ions. It’s the latter that the desalting process removes. Once extracted, the dried recyclable plastic is strong and durable. The researchers say that without the desalting process, the resulting material is brittle, making it unusable.

recyclable plastic dissolves sea all images courtesy of RIKEN Center for Emergent Matter Science, unless stated otherwise

recyclable plastic that fully dissolves in the sea

Because of the mixed monomers, the recyclable plastic dissolves in a few hours when placed back in seawater. The study – which is a collaboration between the RIKEN Center for Emergent Matter Science (CEMS), the University of Tokyo, and Eindhoven University of Technology – paves the way for potentially producing commercial ocean-degradable plastic objects, including bottles and containers. The team gathers that the new plastics are also non-toxic and non-flammable. This means they produce no carbon emissions and can be reshaped at temperatures above 120 degrees Celsius like other thermoplastics.

The researchers have also experimented with different types of guanidinium sulfates, one of the mononers. With this, they’re able to discover that the generated recyclable plastics that dissolve in the sea can be customized depending on the user’s needs. They’re also scratch-resistant and can be molded into rubber-silicon-like, strong weight-bearing, or low-tensile flexible plastics. The developed material is also ideal for 3D printing to produce medical or health-related tools. In this case, users add in polysaccharides to form salt bridges with the monomers.

recyclable plastic dissolves sea the researchers use supramolecular plastics with structures held together by reversible interactions

when placed in soil, the invention decomposes in 10 days

When the recyclable plastic fully dissolves in the sea, the researchers discover that most of the materials can be reused, making the new material recycle-efficient. The team adds that when placed in soil, the invention completely decomposes in around ten days. Then, as it breaks down in the earth, the recyclable plastic releases phosphorus and nitrogen, which are nutrients found in fertilizers.

Traditional plastics don’t break down easily and cause pollution. While some new plastics can break down naturally, many of the biodegradable ones still don’t dissolve in the sea or in water. In this case, they don’t degrade properly, adding to the pollution. Over time, they break into tiny pieces, the microplastics. The researchers attempt to avoid it from the onset, hence studying the use of ionic monomers to produce recyclable plastic that dissolves in the sea.

recyclable plastic dissolves sea bacteria can break down both of these materials or monomers, making the recyclable plastic fully dissolvable

a process called ‘desalting’ helps the recyclable plastic dissolve in the sea | image by Naja Bertolt Jensen

the researchers say that without the desalting process, the resulting material is unusable | image by Aboodi Vesakaran the researchers say the desalting process makes the material durable | image by Aboodi Vesakaran