Researchers of the University of Cambridge developed a polymer film made from plant proteins, mimicking the properties of spider silk, which could replace plastic packaging.

The material was created using a new approach for assembling plant proteins into materials that mimic spider silk. Spider silk is one of the strongest natural materials. The new material is as strong as many common plastics currently used and could replace plastic in many common household products.

The researchers replicated the structures found in spider silk by using soy protein isolate, a protein with a completely different composition. Soy protein isolate is an abundantly available by-product of soybean oil production. All proteins are made f polypeptide chains, which, under the right conditions, can be self-assembled to resemble spider silk in this case.

Plant proteins are poorly soluble in water, making it hard to control their self0assembly into ordered structures. Instead, the Cambridge researchers used an environmentally friendly mixture of acetic acid and water, combined with ultrasonication and high temperatures, to make the proteins soluble.

The plastic-free silk can be made at industrial scale, using an energy efficient method. It can be coloured using non-fading ‘structural’ colouring, and it can be used to make water-resistant coatings as well. The material is home compostable, rather than having to be composted at industrial facilities like many bioplastics.

Image: University of Cambridge