Plant based material could replace single use plastic
Siobhan Treacy | June 14, 2021Researchers from the University of Cambridge created a plant-based, sustainable and scalable material that could replace single-use plastics in many consumer products. The polymer film was developed by mimicking the properties of spider silk, which is known as one of the strongest materials in nature.
At the beginning of their research, the team wondered, why are materials like spider silk so strong when they have weak molecular bonds? The key is hydrogen bonds arranged regularly at a high density.
The team set out to recreate this regular self-assembly in other proteins. Proteins have a propensity for molecular self-organization and self-assembly. Plant proteins are abundant and can be source sustainably as food industry by-products.
Researchers have created a plant-based, sustainable, scalable material that could replace single-use plastics in many consumer products. Source: Xampla
Plastic replacements need a second polymer to add strength. In nature, second polymers are polysaccharides and polypeptides. Cellulose and nanocellulose, types of polysaccharides, are typically used in plastic replacements. These proteins have a range of applications, but they need cross-linking to create a strong material. Crosslinking is typically used to improve performance and resistance but the required ingredients are nonsustainable and can be toxic. There are proteins that can self-assemble and form strong materials without chemical modifications but they are hard to work with.
The team used soy protein isolate (SPI), a byproduct of soybean oil production, to test plant protein strength and to recreate the structures found in spider silk. While it proved to be a promising material, SPI is poorly soluble in water and it is hard to control the self-assembly into ordered structures.
To overcome these issues, a new assembly technique based on an environmentally friendly mix of acetic acid and water with ultrasonication and high temperatures was developed to improve SPI solubility. This method creates protein structures with enhanced intermolecular interactions guided by hydrogen bond formation. When the solvent is removed, the resulting film is water-insoluble.
Ensuring that material is just as strong as single-use plastics is the key to creating a viable replacement product. The production method is energy efficient with sustainable ingredients, and the resulting material has a performance equivalent of most high-performance engineered plastics. The materials’ strength lies in the regular arrangement of polypeptide chains, which means there is no need for chemical cross-linking. The new material is even home compostable.
A paper on the new material was published in Nature Communications.
The single use bio-degradable plastics are zero-carbon net, but here is a place where you don’t WANT that!
A petroleum plastic that goes into a landfill and never degrades does the same job. That carbon is sequestered and doesn’t count. It is as though the petroleum for it was never pumped up.
In addition, it costs a surprising amount of fossil fuel to fertilize, plant, harvest, and process crops for bioplastics. That goes into the air. Do the full calculation and you may well find that bioplastics are less “green” than the old kind, provided you landfill and don’t burn.