Sugar-based polymers enhance plastic circularity in new transatlantic research
27 Jan 2022 --- Researchers from the University of Birmingham, UK, and Duke University, US, have developed a new polymers family from sugar-based materials. The polymers retain the same qualities as common plastics, but are both degradable and mechanically recyclable.
To create two new types of polymer, the scientists used sugar-based starting materials, rather than petrochemical derivatives. While one of the new polymers is stretchable like rubber, the other is tough but ductile, like most commercial plastics.
Furthermore, the chemical similarity of the polymers means that, unlike a lot of current commodity plastics, they can be blended together to yield materials with comparable or improved properties.
“The ability to blend these polymers together to create useful material offers a distinct advantage in recycling, which often has to deal with mixed feeds,” explains Dr. Josh Worch from Birmingham’s School of Chemistry and co-author in the research.
Dr. Connor Stubbs, also from Birmingham’s School of Chemistry, adds: “Petrol-based plastics have had decades of research, so catching up with them is a huge challenge. We can look to the unique structures and shapes that biology have to offer to create far better plastics with the same expanse of properties that current commercial plastics can offer.”
Polymer creation process
The researchers made the new polymers using isoidide and isomannide as building blocks and say that both of these compounds are made from sugar alcohols and feature a rigid ring of atoms.
The researchers found that the isoidide-based polymer showed a stiffness and malleability similar to common plastics, and a strength that is similar to high-grade engineering plastics such as Nylon-6.
The polymers’ chemical similarity means that, unlike common plastics, they can be blended together to yield materials with improved properties.Despite isoidide and isomannide only differing by the 3D spatial orientation of two bonds, known as stereochemistry, the isomannide-based material had similar strength and toughness but also showed high elasticity, recovering its shape after deformation.
Notably, the materials retained their “excellent” mechanical properties following pulverization and thermal processing, which is the usual method for mechanically recycling plastics.
The findings
By creating copolymers that contain both isoidide and isomannide units, the researchers found that they could control the mechanical properties and degradation rates independently of one another. Hence, this system opens the door to using the unique shapes of sugars to independently tune the degradability for a specific use without significantly altering the material’s properties.
Duke University professor Dr. Matthew Becker says: “Our findings really demonstrate how stereochemistry can be used as a central theme to design [environmentally] sustainable materials with what truly are unprecedented mechanical properties.”
New research
Last year, researchers at US universities Berkeley California and Minnesota developed a new chemical fermentation technology for producing food-grade plastic products from plant-based sources. The researchers say their development processes are now being optimized, while commercialization presents an “exciting” possibility.
Meanwhile, seaweed-based packaging manufacturer Notpla is producing films, coatings, sachets, pipettes and paper products entirely from algae.
Edited
By Natalie Schwertheim
