Eugene Chen, a chemist at the Colorado State University, experimented on the monomer Gamma-butyrolactone to produce a biopolymer that can be fully recycled back to its original monomer state for re-use.
The statistics show that on average more than 200 pounds of synthetic polymers (most of these not biorenewable/biodegradable) are utilised per person each year and plastics are taking the number one spot in years production and waste.
Each year, around 10-20 million tons of plastic finds its way in to the Earth’s oceans, in total an estimated 5.25 trillion plastic fragments, weighing 268,940 tons. This plastic remains results in an estimated loss of $13 billion each year from damage that is done to the oceans ecosystem.
Until the discovery, currently available bioplastics like the PLA could only undergo partial thermal recycling. In contrast, the biopolymer developed by Chen called poly(GBL) can be recycled to its base monomer form using a heat reaction. From its base GBL monomer, the polymerisation process can commence again for use in future plastic products.
GBL is a colorless liquid that has a variety of uses among which are as a superglue remover and a cleaning solution. Prior to Chen’s breakthrough, the scientific community had theorized that converting GBL to a polymer was not possible.
Chen and his partner, Miao Hong, thought otherwise and conducted experiments. Eventually, they discovered a method that led to the production of poly(GBL) from GBL. Going further, the duo developed a technique to make shapes using the polymer.
Chen and Hong were able to create linear and cyclic versions of the polymer by varying the catalysts used and the reaction conditions of the production process.
Chen’s team specially designed reaction conditions, along with the low temperature, to make the polymer and heat between 220-300 degrees Celsius to convert the polymer back into the original monomer, showing that polymer is thermal recyclable.
Poly(GBL) has similarities with the commonly used biodegradable bioplastic—P4HB. However, compared to P4HB, poly(GHB) is cheaper to produce, is more abundant and is a more environmentally-friendly alternative. Thus making the poly(GHB) an increasingly potential replacement to the P4HB that will soothe the growing demand of bioplastics.
These properties of the poly(GBL) underscore its immense industry-changing potential. It is importantly petroleum-free, can be broken down by living organisms (biodegradable) and can be fully recycled for future use.
Chen and Hong have published the discovery in a recent issue of Nature Chemistry journal. Chen has also filed a provisional patent for the discovery and recently received the Presidential Green Chemistry Challenge Award.