From inert carbon chains to closed-loop recycling: emerging polyolefin chemistry enabled by telechelic (macro)monomers

Polyolefins have become the most widely produced class of organic polymers due to their low cost and outstanding comprehensive properties. However, their intrinsic chemical inertness makes efficient recycling, especially closed-loop recycling, highly challenging. In recent years, the modular assembly-reversible depolymerization strategy using telechelic polyolefin (tPO) (macro)monomers has provided a new route for introducing controllable depolymerizable sites into polyolefin backbones, which enable closed-loop chemical recycling. This review focuses on the end-group chemistry and linkage modes of tPO (macro)monomers, systematically summarizing the polymerization and depolymerization chemistry based on ester and silyl ether, and olefinic linkages. The molecular weight and dispersity, thermal and mechanical properties, and recyclability metrics (including depolymerization conditions, (macro)monomer recovery efficiency, and property retention) of these systems are compared with those of commercial HDPE, LLDPE, PP, and OBC. Finally, perspectives are proposed regarding the diversification of telechelic modules, the balance between stability and reversibility, and the green, low-carbon synthesis and polymerization-depolymerization cycles of tPO-based circular polyolefin(-like) materials.