A novel, degradable plastic material has been developed by researchers from China’s Huazhong University of Science and Technology, and it came into existence while working on an advanced type of chemical sensor.
The researchers were developing a polymer film that changes colour depending on pH levels, but then noticed that the plastic’s natural deep red colour faded quickly, and the plastic film broke apart over several days in sunlight.
“In conjugated polymers such as this, which have a long backbone chain of alternating double and single bonds, the material’s colour comes from its molecular structure – long chains of monomers – rather than a dye. Loss of that colour means the chains have broken down into their monomer units,” explained researchers.
Breaking these bonds is a common goal of research into better recycling of plastics, which means that the scientists accidentally created a promising, environmentally degradable version of this material.
Plastic waste chokes shorelines and oceans, in part because plastic polymers do not easily decompose. This would not be the case if every plastic, like the new one, could break down in about a week in sunlight and air.
Techniques such as chemical characterisation using nuclear magnetic resonance (NMR) and mass spectroscopy showed that this plastic decomposes rapidly in sunlight from a petroleum-based polymer into succinic acid, a naturally occurring non-toxic small molecule that doesn’t leave microplastic fragments in the environment.
A sun-sensitive plastic might not be a good choice for bottles or bags that need to last more than a week on the shelves. However, integrating the environmentally degradable polymer as a minor ingredient or with other biodegradable polymers could help speed the breakdown of these materials in landfills.