Depolymerization by transition metal complexes: strategic approaches to convert polymeric waste into feedstocks

At present, plastic pollution is a global environmental catastrophe and a major threat to mankind. Moreover, the increasing manufacture of various plastic products is causing rapid depletion of precious resources. Thus, transforming plastic waste into feedstock, which can maintain a circular economy, has emerged as a significant technique for waste management and carbon resource conservation. Furthermore, the urgent development of effective depolymerization methods is vital to save our planet from man-made plastic pollution. Among various chemical depolymerization techniques developed thus far, cleavage of the polymeric skeleton by transition metal complexes is a highly emerging, effective and exciting strategy. In this context, herein, we have summarized mechanistic approaches for cleaving various polymeric bonds using organometallic catalysts. The recently developed strategies, catalyst design and mechanisms for depolymerization of synthetic and natural polymers with polar (C-N, C-O, C-Cl, and Si-O) and non-polar (C-C) skeletal bonds are systematically discussed in detail.