Polyolefins and Polystyrene as Chemical Resources for a Sustainable Future: Challenges, Advances, and Prospects

Nonbiodegradable plastics with inert and saturated C–C backbones comprise the majority of global annual plastics produced, including the ubiquitous polyolefins (polyethylene and polypropylene) and polystyrene. Unlike polymers with cleavable bonds, such as polyesters, polyurethanes, and polycarbonates, these inert plastics are the most challenging to upcycle and cannot be easily broken down by chemical or enzymatic means. Thus, they mostly end up in landfills or are incinerated to produce copious amounts of greenhouse emissions. In recent years, increased research effort has been focused toward the upcycling of low-value plastic waste to give them a new lease of life. However, the unreactive C–C polymer backbones of these plastics have posed formidable challenges for attempts at post-synthetic chemical functionalization and conversion into commodity chemicals. In this Perspective, we discuss these inert plastics as large untapped resources for the production of new functional polymeric materials and valuable industrially relevant feedstock, such as dicarboxylic acids and aromatic compounds. The exciting pioneering work featured herein will hopefully inspire a change in the way we view these waste plastics from a chemical dead-end to versatile raw materials, forming the basis of a more sustainable materials economy.