The world fell in love with plastics because they are cheap, strong, light and durable. Those same properties are turning plastics into an enemy of the earth, they are polluting our planet by land and sea.
Chemists from Colorado State University have announced in the journal Science another big step towards sustainable and waste-free materials that could one day compete with conventional plastics. Led by Eugene Chen, a professor in the Department of Chemistry, they have discovered a polymer that shares many of the properties we enjoy in plastics, such as light weight, heat resistance, strength and durability.
But the new polymer, unlike typical petroleum-based plastics, can be brought back to its original state for complete chemical recycling. This can be accomplished without the use of toxic chemicals or complex laboratory procedures.
Polymers are a broad class of materials characterized by long chains of chemically linked repeating molecular units called monomers. Synthetic polymers today include plastics, as well as fibers, ceramics, rubbers, coatings, and many other commercial products.
The work is based on an earlier generation of a chemically recyclable polymer that Chen’s lab first introduced in 2015. Manufacturing the old version required extreme cold conditions that would have limited its industrial potential. The above polymer also had low heat resistance and molecular weight and, although similar to plastic, was relatively soft.
But the fundamental knowledge gained from that study was crucial, Chen said. This led to a design principle for the development of new polymers that are not only chemically recyclable, but also have properties equivalent to conventional plastic.
The new, much improved structure solves the problems of the first generation material. The monomer can be conveniently polymerized under industrially realistic, environmentally friendly conditions: solvent-free, at room temperature, in just a few minutes and with only a small amount of catalyst. The resulting material has a high molecular weight, thermal stability and crystallinity, and mechanical properties very similar to those of a plastic. Most importantly, the polymer can be recycled back to its original monomeric state, using a catalyst. Without the need for further purification, the monomer can be repolymerized, thus establishing what Chen calls a circular life cycle of materials.
” Polymers can be chemically recycled and reused, in principle, infinitely ,” Chen said.
Chen emphasizes that the new polymer technology has only been demonstrated on a laboratory scale. Much work remains to be done to perfect the patent-pending monomer and polymer production processes he and his colleagues have invented.
With the help of an initial grant from CSU Ventures, chemists are optimizing their monomer synthesis process and developing new, more cost-effective techniques for monomers. They are also working on scalability issues in their monomer, polymer, and monomer recycling setup, while also investigating new chemical structures for even better recyclables.
” It would be a dream to see this chemically recyclable polymer technology hit the market, ” said Chen.
Although solutions are being sought to minimize the impact of plastic, such as the plastic-eating worm or the fungus from a Pakistani landfill that is capable of eating plastic, the ultimate long-term solution should certainly not be to counteract the negative effects of plastic. for our planet, but to look for alternatives like the one we are talking about today, that do not destroy it.
Via: Colorado State University.
J.-B. Zhu el al., “A synthetic polymer system with repeatable recyclability,” Science (2018). science.sciencemag.org/cgi/doi… 1126 / science.aar5498
H. Sardon el al., “Plastics recycling with a difference,” Science (2018). science.sciencemag.org/cgi/doi… 1126 / science.aat4997 – https://phys.org/news/2018-04-infinitely-recyclable-polymer-properties-plastics.html#jCp