Researchers create flexible packaging film made from plants

Researchers have developed a new approach for assembling plant proteins into plastic film materials that mimic silk on a molecular level.

Researchers from the University of Cambridge in England have developed a method to create a compostable, plant-based “plastic-like” material that’s as robust as engineering plastics. In a paper published in Nature Communications, researchers from the Knowles Group describe how they can create the polymer film from plant proteins in a sustainable and scalable way. The new material is as strong as the most common plastics in use today and could replace plastic in many common household products. It’s home compostable and will degrade naturally in a marine environment and in fresh water.

To create the material, researchers developed a new approach for assembling plant proteins into materials that mimic silk on a molecular level. The energy-efficient method, which uses sustainable ingredients, results in a plastic-like, freestanding film that can be produced at industrial scale. Non-fading ‘structural’ colour can be added to the polymer, and it can also be used to make water-resistant coatings. The new product will be commercialized by Xampla, a Knowles Lab “spinout” that develops replacements for single-use plastic and micro-plastics.

Tuomas Knowles

Professor Tuomas Knowles, who led the research, added: “One of the key breakthroughs is that we can now control the assembly of natural plant proteins into technologically useful structures. We can also now do this in a scalable way which is critical to actually be able to start replacing plastics in real world applications.” For many years, the Knowles group has been conducting basic research into the behaviour of proteins. Much of the research has been focused on what happens when proteins misfold or ‘misbehave’ – and how this relates to health and human disease, primarily Alzheimer’s disease. “We normally investigate how functional protein interactions allow us to stay healthy and how irregular interactions are implicated in Alzheimer’s disease,” Knowles added. “It was a surprise to find our research could also address a big problem in sustainability: that of plastic pollution.”

As part of their protein research, Knowles and his group became interested in why materials like spider silk could be so strong when they had such weak molecular bonds. “You’d think to obtain strong materials you’d need strong interactions between building blocks, but the building blocks of spider’s silk are based on weak, non-covalent interactions,” he explained. “We found that one of the key features that makes spider silk strong is that the non-covalent hydrogen bonds are arranged regularly in space and at a very high density.” Proteins have a propensity towards molecular self-organization and self-assembly, and plant proteins in particular are abundant and can be sourced sustainably as by-products of the food industry. Currently, little is known about the self-assembly of plant proteins. By filling this knowledge gap, researchers are confident that they can find alternatives to single-use plastics.”

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