Trends in polyester up cycling for diversifying a problematic waste stream

Abstract

We are facing a rapidly growing plastic pollution crisis, which is adversely affecting communities and ecosystems across the globe. Polymer scientists have an urgent obligation to develop and implement strategies for reutilizing plastic waste streams instead of continually relying on virgin feedstocks in plastic manufacturing. Post-consumer and post-industrial plastic items should be treated as valuable resources instead of discarding them. In order to do this, technological outlets must be developed to produce high-value/high-performance materials using plastic waste as an input. Polyesters represent one of the largest plastic waste streams, since they are commonly used in single-use beverage and food containers as well as textiles. Polyesters are also ideal candidates to exploit through chemical diversification, owing to the wide variety of functional derivatives that can be synthetically accessed via ester reactivity. This work highlights some recent developments related to diversifying polyester waste, with a focus on poly(ethylene terephthalate) (PET) as waste stream. The strategies encompass both the production of high-value small molecules prepared via degradation of PET as well as high-performance polymeric scaffolds derived from reactions with PET. Taking the recent ingenuity into consideration, based on these technological developments, an outlook is provided for the future of polyester waste streams. What are the next steps that are needed? Where are these trends headed? What gaps still exist, particularly with respect to assessment of sustainability and life cycle analysis? Collectively considering the examples highlighted here, there is great promise in the field of reutilizing waste streams as feedstocks for value-added materials.