Every year, we dispose of hundreds of millions of tons of plastic
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By incorporating chemicals that imitate natural polymers like DNA into plastics, we can develop materials that decompose in days, months, or years instead of persisting in landfills for centuries. Researchers are optimistic that this innovative approach will produce plastic items that fulfill their function and then safely disintegrate.
In 2022, over 2.5 billion tonnes of plastic are expected to be discarded globally, with merely 14 percent being recycled while the rest is either incinerated or buried. The quest for effective biodegradable plastics has spanned at least 35 years, utilizing various organic sources like bamboo and seaweed. However, in practice, many of these materials prove to be challenging to compost, and their manufacturers often make exaggerated claims.
Currently, Gu Yuwei, a professor at Rutgers University, is working on technology that creates plastics with precisely calibrated lifetimes, allowing them to break down swiftly in compost or natural environments.
Gu questioned why natural long-chain polymers such as DNA and RNA decompose relatively rapidly, while synthetic polymers like plastics do not, and whether it’s possible to replicate this process.
Natural polymers possess chemical structures known as adjacent groups, which facilitate their breakdown. These structures trigger an internal reaction called nucleophilic attack that disrupts the bonds in the polymer chains, which is energetically demanding for standard plastics.
Gu and his team synthesized artificial chemical structures that resemble these adjacent groups and incorporated them during the manufacturing of new plastics. They discovered that the resulting material could degrade easily, and by altering the structure of these additions, they could adjust how long the material remained intact before degradation.
As the plastic decomposes, Gu anticipates that the long polymer chains will fragment into smaller components that can either be repurposed to produce new plastics or dissolve safely in the environment.
“This method is optimized for plastics that require controlled degradation within days to months, so we believe it holds significant potential for uses like food packaging and other transient consumer products,” Gu explains. “It is not currently suitable for plastics that must remain intact for decades, such as construction materials and long-lasting structural components.”
Nonetheless, several challenges must be addressed before these plastics can be used in commercial applications. The liquid residue after the plastic’s decomposition consists of polymer chain fragments, necessitating further testing to ensure this mixture is non-toxic and can be safely released into the ecosystem.
Moreover, while UV light is presently required to initiate the degradation, natural sunlight is enough. Therefore, until the research team discovers a method to create materials that can decompose in darkness, buried or obscured plastics may persist in the environment indefinitely.
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Source: www.newscientist.com
