The problem of the presence and proliferation of microplastics in the sea is One of the great concerns of societywhich already knows that this material from oil is present in the seas and is introduced into the trophic chain.
This problem could come to an end if the bags, bottles, containers, etc., made with this material pollutant, will not reach the aquatic environment, an estimated amount between 4.8 and 12.7 million tons plastic end every year in the oceans.
Microplastics in the sea and on earth
Currently, most plastics are not biodegradable, but decompose from erosion in the environment over time in small particles called microplastics and nanoplastic.
Problems that accumulate because, despite the fact that no more plastics are thrown into the sea, those that are already following decomposing with he time which happens in smaller pieces, in microplastics or nanoplastic.
The microplastics are Very small plastic pieces that are generally considered less than five millimeters of size in at least one dimension. Microplastics can be manufactured to reach that size, such as resin granules used for plastic production, or degrading that size from larger plastics that are discarded in the environment.
Artistic representation of the new plastic according to the researchers. (Photo CEMS)Nanoplastic
The nanoplastic are even smallerbecause they are generally considered less than one µm (micra). As a reference, the diameter of human hair is approximately 70 microns.
The microplastics can be manufactured to that size, such as resin granules used for plastic productionor degrade that size from larger plastics discarded in the environment. Nanoplastic are even smaller, generally considered lower than a µm (micra).
Discovery
But the investigation carried out by a Japanese team, led by Takuzo Aida in the Riken Center for the Science of Emerging Matter (CEMS) has given new hopes against the struggle of plastics and the environmental problem that supposes.
Takuzo aida is a prestigious polymer chemist Known for his work in the fields of supramolecular chemistry, the chemistry of materials and polymer chemistry.
Japanese researchers They have developed a durable plastic that does not contribute to microplastic pollution in our oceans. He New material is as resistant as conventional and biodegradable plasticsbut its particularity lies in that It decomposes in seawater, so it would be the end of microplastics.
Reduce pollution
Therefore, The new plastic is expected to help reduce the harmful microplastic pollution in the sea, which accumulates in the oceans and the ground, and that finally enters the food chain. These experimental findings were published on November 22 in Science magazine.
Scientists They have been trying to develop safe and sustainable materials that can replace traditional plastics, which are not sustainable and damage the environment.
While there are some Recyclable and biodegradable plasticsa big problem persists. The Current biodegradable plastics, such as pla, usually end in the oceanwhere they cannot degrade by be insoluble in water.
«As a result, microplastics (plastic fragments of less than 5 mm) They damage aquatic life and are introduced into the food chainincluding our own body, ”Japanese researchers highlight.
Supramolecular plastics
In his new study, Aida and his team focused on solving this problem with supramolecular plastics: polymers whose structures are kept together by reversible interactions.
The new plastics were manufactured COmbinating two ionic monomers that form reticulated saline bridges, which provides resistance and flexibility.
In the initial tests, one of the monomers was a common food additive Hexametaphosphate of sodium And the other was one of several monomers based on ions of Guanidinio.
Both monomers They can be metabolized by bacteriawhich guarantees its biodegradability once the plastic components dissolved.
New material
«While it was believed that the reversible nature of the links in Supramolecular plastics made them weak and unstable“Aida affirms,” our new materials are just the opposite. “
In the new material, lTo the structure of the saline bridges is irreversible unless it is exposed to electrolytes such as those found in seawater. The key discovery was how to create these selectively irreversible cross bonds.
As with oil and water, After mixing the two monomers in water, the researchers observed two separate liquids. One was thick and viscous, and contained important structural reticulated saline bridges, while the other was aqueous and contained saline ions.
Plastic and garbage floating in the seaDesalination and highlighting
For example, when using sodium hexametaphosphate and alkydiguanidininio sulfate, the Sodium sulfate salt The aqueous layer was expelled. The final plastic, rented sp₂, was obtained by drying what remained in the thick layer of viscous fluid.
The desalination turned out to be the critical step, «without it, the resulting dry material was a fragile, unusable crystal. The highlighting of plastic placing it in salt water caused the reversal of the interactions and the destabilization of its structure in a matter of hours », The research team reveals.
«Therefore, after creating a Resistant and durable plastic that can still dissolve under certain conditions, the researchers tested their quality, ”they say from the Japanese center.
They are not toxic or flammable
The new plastics are not toxic or flammable (that is, they do not emit CO₂) and can be remodeled at temperatures greater than 120 ° C, Like other thermoplastic.
When trying different types of sulfates from Guanidininio, the team managed to generate plastics with different hardness and resistance to traction, all comparable or even better than conventional plastics.
Turtle with a plastic bag aroundDegrable plastics in the ocean
This means that the new type of plastic can be customized according to needs: “You can create hard plastics resistant to scratches, plastics similar to silicone, plastics resistant to flexible low voltage plastics,” they describe.
The researchers also created degradable plastics in the ocean using polysaccharides that form saline bridges with guanidinio monomers. This type of Plastics can be used in 3D printing, as well as medical or health applications.
Recyclable and fertilizer
Finally, the researchers studied the recyclability and biodegradability of the new plastic. After dissolving the new initial plastic in salt water, lOgrated recover 91% of hexametaphosphate and 82% of dust -shaped guanidinium, indicating that recycling is easy and efficient. On the ground, the sheets of the new plastic were completely degraded in 10 days, providing phosphorus and nitrogen similar to a fertilizer.
«With this new material, we have created a new family of plastics that are strong, stable, recyclablethey can fulfill multiple functions and, most importantly, they do not generate microplastics, ”says Aida.
