Insects Inspire New Biodegradable Plastics

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Traditional plastics are the children of oil; they are derived from the photochemical process. Since their inception, synthetic plastics have left an indelible mark on society. According to the U.S. National Park Service, however, plastic bottles can take up to 450 years to fully decompose. While they do eventually degrade, they are not considered truly biodegradable. Instead, they accumulate in landfills and oceans, killing wildlife and polluting our environment.

But researchers at Harvard's Wyss Institute have created an alternative. Based off the shells of insects and shrimp, the team has created a new polymer that is not only strong, but biodegradable as well. The material is based off of the most successful of organisms: insects. These organisms, which consist of 95% of all animal life on the planet, are armored with cuticles that are not only strong, but flexible and light as well.

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Due to its components, chitin and fibroin, the polymer was dubbed Shrilk. Chitin is the main material in insect exoskeletons and is a byproduct of silk production. Fibroin is a protein found in many shellfish and can be derived from shrimp shells. Since the main components of Shrilk are so cheap, and can be acquired so easily, it can be produced at a very low cost.

Shrilk's secret is not just in the chemistry, but also in the way the components are combined. In an insects body, the chitin and fibroin are layered, creating a laminate similar in design to what gives plywood its strength and rigidity. The result of this union is not only a material with the same strength of aluminum alloy at half the weight, but is hydrophilic as well. This allows for its mechanical properties to change depending on the amount of water involved during the fabrication process.

The combination of high strength to weight ratio, modularity, and biodegradability  make Shrilk suitable for a wide range of applications. Plastic bottles, garbage bags, containers, and diapers would all be degradable and eco-friendly. The components of Shrilk are major constituents of fertilizer, so the waste could be used to grow our crops. The material could also be used as scaffolds for tissue implants, sutures, and gauzes. After the wound of the patient has heralded, they need only wait for the material to break down and their own biomass to take its place.

Of course cost is a concern. While the components of Shrilk are very cheap, the process is anything but. But if we can overcome this hurdle, a world where garbage bags, plastic bottles, and six-pack rings cluttering our landfills and floating in our oceans may become a thing of the past.