A New Era in Plastic: Strength Meets Ocean Degradability
Plastic pollution has long been one of the most persistent and damaging environmental problems. Most plastics, built from covalent bonds, are incredibly durable — a trait that’s beneficial in daily use but devastating in nature. They can take hundreds of years to degrade and, even then, often only break into harmful microplastics. In a breakthrough study, researchers led by Takuzo Aida at the RIKEN Center for Emergent Matter Science (CEMS) in Japan have tackled this issue by creating a plastic that is strong during use but completely dissolves in seawater without leaving microplastics behind.
This innovative plastic, developed through a collaboration between RIKEN CEMS, the University of Tokyo, and Eindhoven University of Technology, uses a method grounded in supramolecular chemistry. The material’s structure is held together by reversible, non-covalent interactions rather than traditional permanent chemical bonds. These bonds make the plastic durable and moldable when dry but allow it to break down when exposed to the right environmental conditions.
The Science Behind the Sea-Friendly Plastic
The key to this breakthrough lies in the combination of two ionic monomers: sodium hexametaphosphate, a common food additive, and guanidinium ion-based compounds. These form cross-linked salt bridges — interactions that can be reversed in the presence of electrolytes, such as those found in seawater. Once the plastic is exposed to saltwater, these reversible bonds destabilize, causing the structure to dissolve in just a few hours.
A critical part of the process is “desalting.” When the monomers are mixed in water, they separate into two distinct layers: one viscous and rich in the structural components, and the other watery and filled with salt ions. Removing the salt ions is essential to form a strong, durable material. Without this desalting process, the resulting material becomes brittle and unusable. Once dried and desalted, however, the plastic becomes robust, scratch-resistant, and capable of being reshaped at temperatures above 120°C — ideal for a variety of applications, including 3D printing and medical tools.
Biodegradable and Customizable for Various Needs
Unlike many biodegradable plastics that fail to break down in marine environments, this new plastic dissolves entirely in seawater. Moreover, it’s biodegradable on land too. When placed in soil, it decomposes within ten days, releasing nutrients like nitrogen and phosphorus, both commonly found in fertilizers. This dual degradation property makes it highly versatile and environmentally beneficial.
The research team also explored how the properties of the plastic could be customized by altering the guanidinium-based monomers. This allowed them to produce variations ranging from rubbery, silicone-like textures to strong, weight-bearing forms or more flexible, low-tensile materials. The flexibility in formulation paves the way for wide commercial use — from packaging and containers to specialized medical equipment.
A Step Towards a Plastic-Free Ocean
Traditional plastic waste remains one of the most pressing environmental threats, particularly in marine ecosystems. The ability of this new plastic to completely degrade without producing microplastics represents a monumental step forward. Not only is it safe for wildlife and non-toxic to the environment, but it also contributes positively to soil health. With the potential to replace conventional single-use plastics, the development signals a future where strength and sustainability coexist.
According to Takuzo Aida, “With this new material, we have created a new family of plastics that are strong, stable, recyclable, can serve multiple functions, and importantly, do not generate microplastics.” The innovation demonstrates that environmentally friendly materials no longer have to compromise on performance, offering a genuine alternative for industries and consumers seeking sustainable solutions.
