Polyethylene is the most produced synthetic polymer, accounting for about one-third of all plastic production. Despite its low greenhouse gas emissions per unit mass, polyethylene's environmental persistence is a major concern due to its chemical inertness and crystalline structure. Current recycling methods are limited, and most plastic waste ends up in landfills or is released into the environment. Chemical recycling, particularly under mild conditions (<200°C), offers a promising alternative for deconstructing polyethylene into reusable smaller molecules. This can be achieved by introducing predetermined breaking points in polyethylene chains during synthesis or through post-polymerization functionalization, such as dehydrogenation or oxidation to long-chain dicarboxylates. These methods can help break down polyethylene litter, reducing its environmental persistence. The synthesis of polyethylene-type materials tailored for deconstruction involves introducing functional groups that serve as breaking points. Chain-growth and step-growth polymerizations can incorporate these groups. For example, chain-growth polymers can include functional groups via copolymerization with functional comonomers, while step-growth polymers can be synthesized through polycondensation of long-chain difunctional monomers. Post-polymerization functionalization, such as oxidation or dehydrogenation, can also introduce functional groups. These functional groups enable deconstruction under mild conditions, facilitating chemical recycling and upcycling. Recent advances in catalytic polymerization have enabled the synthesis of polyethylene-type materials with low densities of in-chain functional groups. For instance, catalytic copolymerizations of ethylene with CO have produced keto-modified polyethylene with controlled molecular weights and properties. These materials can be further modified through chemical reactions to enhance their degradability and recyclability. Additionally, ring-opening metathesis polymerization (ROMP) of cyclic monomers can produce long-chain telechelic molecules, which can be used as building blocks for recyclable polyethylene-like polymers. Step-growth polymerization of long-chain dicarboxylic acids and diols can yield polyesters with controlled functional groups. These polyesters can have properties similar to polyethylene, including crystallinity and mechanical strength. The incorporation of ester groups into the crystalline lattice can affect the melting point and crystallinity of the material. The use of long-chain dicarboxylic acids and diols from renewable sources or plastic waste offers a sustainable approach to producing polyethylene-type materials. Overall, the synthesis and deconstruction of polyethylene-type materials are critical for developing a more sustainable plastic economy.Polyethylene is the most produced synthetic polymer, accounting for about one-third of all plastic production. Despite its low greenhouse gas emissions per unit mass, polyethylene's environmental persistence is a major concern due to its chemical inertness and crystalline structure. Current recycling methods are limited, and most plastic waste ends up in landfills or is released into the environment. Chemical recycling, particularly under mild conditions (<200°C), offers a promising alternative for deconstructing polyethylene into reusable smaller molecules. This can be achieved by introducing predetermined breaking points in polyethylene chains during synthesis or through post-polymerization functionalization, such as dehydrogenation or oxidation to long-chain dicarboxylates. These methods can help break down polyethylene litter, reducing its environmental persistence. The synthesis of polyethylene-type materials tailored for deconstruction involves introducing functional groups that serve as breaking points. Chain-growth and step-growth polymerizations can incorporate these groups. For example, chain-growth polymers can include functional groups via copolymerization with functional comonomers, while step-growth polymers can be synthesized through polycondensation of long-chain difunctional monomers. Post-polymerization functionalization, such as oxidation or dehydrogenation, can also introduce functional groups. These functional groups enable deconstruction under mild conditions, facilitating chemical recycling and upcycling. Recent advances in catalytic polymerization have enabled the synthesis of polyethylene-type materials with low densities of in-chain functional groups. For instance, catalytic copolymerizations of ethylene with CO have produced keto-modified polyethylene with controlled molecular weights and properties. These materials can be further modified through chemical reactions to enhance their degradability and recyclability. Additionally, ring-opening metathesis polymerization (ROMP) of cyclic monomers can produce long-chain telechelic molecules, which can be used as building blocks for recyclable polyethylene-like polymers. Step-growth polymerization of long-chain dicarboxylic acids and diols can yield polyesters with controlled functional groups. These polyesters can have properties similar to polyethylene, including crystallinity and mechanical strength. The incorporation of ester groups into the crystalline lattice can affect the melting point and crystallinity of the material. The use of long-chain dicarboxylic acids and diols from renewable sources or plastic waste offers a sustainable approach to producing polyethylene-type materials. Overall, the synthesis and deconstruction of polyethylene-type materials are critical for developing a more sustainable plastic economy.