This diagram shows how sugar and carbon dioxide are converted into plastic
Some biodegradable plastics could be made in the future using sugar and carbon dioxide to replace unsustainable plastics made from crude oil, following research by scientists from the Centre for Sustainable Chemical Technologies (CSCT) at the University of Bath
● Polycarbonate is used to make drinks bottles, eyeglass lenses, and scratch-resistant coatings for phones, CDs, and DVDs.
● Current polycarbonate manufacturing processes use bisphenol A (BPA) (banned for use in baby bottles) and the highly toxic phosgene, which was used as a chemical weapon in World War I.
● Scientists at the University of Bath have developed an alternative polycarbonate made from sugars and carbon dioxide using a new process that uses low pressure and room temperature, making it cheaper and safer to produce.
● This new type of polycarbonate can be degraded back into carbon dioxide and sugar using enzymes from soil bacteria.
● This new plastic is biocompatible, so it could be used in the future in medical implants or as scaffolds for growing replacement implantable devices.
Polycarbonates from sugars provide a more sustainable alternative to traditional polycarbonates made from bisphenol A (BPA), but this process uses a highly toxic chemical called phosgene. Scientists at Bath have developed a safer and more sustainable alternative, adding carbon dioxide to the sugar at low pressure and at room temperature.
The resulting plastic has similar physical properties to those derived from petrochemicals, such as being strong, transparent, and scratch-resistant. The main difference is that it can be degraded back into carbon dioxide and sugar using enzymes found in soil bacteria.
This BPA-free plastic could replace existing polycarbonates in materials such as baby bottles and food containers. Because it is biocompatible, it could also be used in medical implants or as scaffolds for growing tissues or organs for transplantation.
Dr. Antoine Bouchard, from the University's Department of Chemistry, says: "There is an increasing demand for plastics due to the growing population. This new plastic can be considered a renewable alternative to fossil-fuel-based polymers. It is inexpensive, biodegradable, and does not contribute to the increasing waste in oceans and landfills."
He adds: "Our process uses carbon dioxide instead of the highly toxic chemical phosgene and produces plastic free of bisphenol A (BPA). So not only is the plastic safer, but its manufacturing process is also cleaner."
Dr. Bouchard and his team at the Centre for Sustainable Chemical Technologies have published their work in a series of articles in the journals Polymer Chemistry and Macromolecules.
The team used nature as inspiration for the process, using a sugar found in DNA called thymidine as a building block to create the new, versatile polycarbonate plastic.
PhD student Georgina Gregory, the first author of the articles, explained: "Thymidine is one of the building blocks of DNA because it's already present in the body. This means this plastic will be biocompatible and can be safely used in tissue engineering applications."
"The properties of this new plastic can be fine-tuned by altering its chemical composition. For example, we can make the plastic charged so that cells can adhere to it, making it useful as a scaffold for tissue engineering." This tissue engineering work has already begun in collaboration with Dr. Ram Sharma of Chemical Engineering, who is also part of the Centre for Sustainable Chemical Technologies.
The researchers are also looking into using other sugars such as ribose and mannose. Dr. Bouchard adds: "Chemists have 100 years of experience using petrochemicals as raw materials, so we need to start over by using renewable raw materials like sugars as a base for industrial but sustainable materials. We're still in the early stages, but the future looks promising."