Scientists find a sustainable alternative to single-use plastics
Scientists have found a sustainable alternative ‘Vegan spider silk’ to single-use plastics for use in household consumer goods. A team of researchers created a plant-based, sustainable, scalable material to replace single-use plastics in consumer products.
Researchers drawn from the University of Cambridge designed a polymer film by imitating the properties of spider silk. Spider silk is one of the known strongest materials in nature. It is as strong as common plastics in use today and could replace single-use plastics.
Polythene is the most common plastic across the globe, widely used from plastic packaging bags to food packaging. The move is deemed to significantly reduce plastic pollution globally and make the environment more sustainable
Despite the global measures put in place to control the use of plastics, the waste keeps on pilling up. A United Nations 2018 report estimated that 13 million tonnes of plastic waste enter into oceans every year. This has threatened the marine ecosystem endangering aquatic life.
The material was created by assembling plant proteins into materials that imitate silk on a molecular level. The energy-efficient method uses sustainable ingredients which results in a plastic-like free-standing film. It can be made on an industrial scale. Non-fading ‘structural’ color can be added to the polymer, and it can also be used to make water-resistant coats.
Whereas the other types of bioplastics require industrial composting facilities to degrade, this material is home compostable. In addition, the material requires no chemical modifications to its natural building blocks to safely degrade in natural environments.
To develop the material, scientists replicated the structures found on spider silk by using soy protein isolate, a protein with a completely different composition. “Because all proteins are made of polypeptide chains, under the right conditions we can cause plant proteins to self-assemble just like spider silk,” said Professor Tuomas Knowles in Cambridge’s Yusuf Hamied Department of Chemistry. “In a spider, the silk protein is dissolved in an aqueous solution, which then assembles into an immensely strong fiber through a spinning process which requires very little energy.”
“Other researchers have been working directly with silk materials as a plastic replacement, but they’re still an animal product,” said Rodriguez Garcia. “In a way we’ve come up with ‘vegan spider silk’—we’ve created the same material without the spider.”
This new technique uses an eco-friendly mixture of acetic acid and water, combined with ultrasonication and high temperatures. This method produces protein structures with enhanced intermolecular interactions guided by hydrogen bond formation.
In a second step, the solvent is removed, which results in a water-insoluble film.
The material has a performance equivalent to high-performance engineering plastics such as low-density polyethylene. Its strength lies in the regular arrangement of the polypeptide chains, meaning there is no need for chemical cross-linking, which is frequently used to improve the performance and resistance of biopolymer films. The most commonly used cross-linking agents are non-sustainable and can even be toxic, whereas no toxic elements are required for the Cambridge-developed technique.
“This is the culmination of something we’ve been working on for over ten years, which is understanding how nature generates materials from proteins,” said Knowles. “We didn’t set out to solve a sustainability challenge—we were motivated by curiosity as to how to create strong materials from weak interactions.”
“The key breakthrough here is being able to control self-assembly, so we can now create high-performance materials,” said Rodriguez Garcia. “It’s exciting to be part of this journey. There is a huge, huge issue of plastic pollution in the world, and we are in the fortunate position to be able to do something about it.”