Polymeric materials, in particular polyolefin plastics, are an irreplaceable part of all aspects of modern life, such as medical practice, food packaging, and construction. However, their slow decomposition and incompatibilities with our sensitive ecosystems have led to a global plastics waste catastrophe. Classical mechanical recycling technologies have failed to address this crisis because recycled polymers are of a significantly lower quality than virgin materials. Thus, the recycled materials can only be used for specific applications where a lower quality material is acceptable, which does not enable a circular economy. An alternative to classical recycling would be the development of upcycling technologies that utilize plastic waste as a feedstock to synthesize value-added products. One of the challenges associated with the use of plastics as a feedstock, however, is to achieve a narrow distribution of product molecules. Nature performs the selective deconstruction of flexible macromolecules, such as proteins, cellulose, or even synthetic polymers, by first threading the molecule into a tunnel containing the active site. This tunneling enables the enzyme to have high structural precision and enact processive reactions through a polymeric chain. These processive reactions convert the polymer chain into molecular-level-controlled products. Our research demonstrated that a specially designed mesoporous shell-metal-core structure (mSiO2/Pt/SiO2) could achieve the depolymerization of high-density polyethylene through a similar processive mechanism employed in natural enzymes and achieve a narrow product distribution. This discovery is supported by advanced NMR characterization and detailed reaction studies. Our work shows the potential benefits of processive catalytic transformation for upcycling single-use plastics.

The design of a processive catalyst for the upcycling of polyethylene

ACS Spring Meeting 2021

The official archive and repository for all ACS Meetings & Expositions abstracts and select posters or presentations.