The development of high-performance recyclable polymers represents a circular plastics economy to address the urgent issues of plastic sustainability. Herein, we design a series of biobased seven-membered-ring esters containing aromatic and aliphatic moieties. Ring-opening polymerization studies showed that they readily polymerize with excellent activity (TOF up to 2.1 × 105 h–1) at room temperature and produce polymers with high molecular weight (M n up to 438 kg/mol). The variety of functionalities allows us to investigate the substitution effect on polymerizability/recyclability of monomers and properties of polymers (such as T gs from −1 to 79 °C). Remarkably, a stereocomplexed P­(M2) exhibited significantly increased T m and crystallization rate. More importantly, product P­(M)­s were capable of depolymerizing into their monomers in solution or bulk with high efficiency, thus establishing their circular life cycle.

The development of innovative synthetic polymer systems to overcome the trade‐offs between the polymer's depolymerizability and performance properties is in high demand for advanced material applications and sustainable development. In this contribution, we prepared a class of aromatic cyclic esters (M1–M5) from thiosalicylic acid and epoxides by facile one‐pot synthesis. Ring‐opening polymerization of Ms afforded aromatic polyesters P(M)s with high molecular weights and narrow dispersities. The physical and mechanical properties of P(M)s can be modulated by stereocomplexation and regulation of the side‐chain flexibility of the polymers, ultimately achieving high‐performance properties such as high thermal stability and crystallinity (Tm up to 209 °C), as well as polyolefin‐like high mechanical strength, ductility, and toughness. Furthermore, the functionalizable moieties of P(M)s have driven a wide array of post‐polymerization modifications toward access to value‐added materials. More importantly, the P(M)s were able to selectively depolymerize into monomers in excellent yields, thus establishing its circular life cycle.

Monomer design is vital in the development of polymers with desired thermal and mechanical properties. Here, we prepared two monomers (M1, trans-octahydro-2H-benzo [b][1,4]dioxepin-2-one and M2, trans-octahydro-2H-benzo[b][1,4]oxathiepin-2-one) based on 1,5-dioxepan-2-one (DXO) and 1,4-oxathiepan-7-one (OTO) by incorporating trans-fused cyclohexyl rings. These monomers featured living ring-opening polymerization-yielding polymers with predictable molecular weights while maintaining low D̵ values. To gain a better understanding of the influence of polymer tacticity on polymer properties, a series of polymers with variable tacticities were prepared under various conditions. Their thermal property studies revealed that increasing the P r value to 91% of P(M2) led to an emerging melting-transition temperature of 101 °C. Copolymerization of M1 and M2 allowed us to obtain a well-defined diblock polymer P(M2)-b-P(M1) and random copolymer P(M1-co-M2) with distinct thermal behaviors. Excitingly, oxidation of P(M2) resulted in an increase of the glass transition temperature from 18 to 112 °C. Hydrolysis of these polymers to corresponding hydroxyl acids and subsequent lactonization reactions enabled a closed-loop life cycle of P(M)s.

Biobased materials have served as an attractive alternative to replace current petroleum-based plastics because of their abundant biorenewable feedstocks and potential degradability.Here we prepared a class of seven-membered ring carbonates containing biobased Diels−Alder adduct moieties. The bifunctional monomers M1 and M2 exhibited excellent reactivity for both ringopening polymerization and ring-opening metathesis polymerization, yielding functionalizable aliphatic polycarbonates and poly(cyclic olefin)s with a range of T g values from 84 to 194 °C. The resulting polymers can be postpolymerization functionalized by "click", crosslinking, hydrogenation, hydrolysis, and retro-Diels−Alder reactions, which appeared to be powerful tools to tune the thermal and mechanical properties of the resulting polymers. Ultimately, the resulting polycarbonate P(M1) ROP -SC 6 H 13 possessed polyolefin-like mechanical performance. These polycarbonates can be completely hydrolyzed into their corresponding starting material diols, demonstrating a potential close-loop life cycle of P(M) ROP . Remarkably, this novel monomer design strategy enabled diverse functionalities to be incorporated, providing access to biobased materials with tunable properties.

The development of chemically recyclable polymers with cheap price and high-performance properties serves as a promising strategy to solve the plastic pollution issues. In this contribution, we prepared a series...