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Although great successes have been achieved, the preparation of closed‐loop recyclable polyesters with high working temperatures still remains as a big challenge. Herein, we present the syntheses of a series of enantiopure bicyclic ether‐ester monomers by upcycling of poly(3‐hydroxybutyrate) bioplastic. The "living"/controlled ring‐opening polymerizations of these enantiopure monomers to produce stereoregular polyesters with controlled molecular weights and well‐defined chain ends were achieved. The effects of stereoconfiguration and substituent on polymerization kinetics and thermodynamics as well as the thermal properties of resultant polyesters were investigated. Of note, the stereoregular polyesters are semi‐crystalline materials with melting temperatures up to 176 °C, even higher than the commodity polyolefin plastics. These polyesters can be depolymerized back to recover pristine monomers, thus successfully establishing a closed‐loop life cycle. [ABSTRACT FROM AUTHOR]

It is a highly attractive strategy to develop chemically recyclable polymers to establish a circular plastic economy. Despite the recent advancements, chemically recyclable polymers still face challenges including high energy cost for polymer preparation or recycling, poor monomer recovery selectivity and efficiency as well as undesired material performance. In this contribution, we present the chemoselective controlled ring‐opening polymerization of bio‐renewable bifunctional α‐methylene‐δ‐valerolactone (MVL) to produce exclusive functionalizable polyester using strong base/urea binary catalysts. The obtained polyester with high molar mass exhibits good tensile strength comparable to that of some commodity plastics. Remarkably, the obtained polyester can be depolymerized to recover pristine monomer with a 96 % yield by thermolysis, thus successfully establishing a closed‐loop life cycle. [ABSTRACT FROM AUTHOR]

Smart polymeric materials have received extensive attention for various applications. Here, we reported a facile and efficient approach to prepare a class of pegylated polypeptoids by a combination of ring-opening polymerization (ROP) and post-modification strategy. Three different initiators were involved to mediate the polymerization of the monomers. Unlike the previously reported pegylated polypeptoids, the obtained polypeptoids show completely reversible thermoresponsive behaviors in aqueous solution after 8 heating and cooling cycles. In addition, the phase transition of the polypeptoid solutions can be very sharp (ΔT < 5 °C), which is comparable to poly( N -isopropylacrylamide) (PNIPAM). The influence of temperature on solution properties of the polypeptoids has been systematically studied. The clouding points (CPs) of the polypeptoids are highly tunable depending on the degree of polymerization (DP), the side-chain length, and the polymer concentration. We demonstrate that the thermoresponsive property of the polypeptoid may possibly arise from the incorporation of thioether groups and the branched molecular architecure of side chains. These features enable the pegylated polypeptoids potential candidates for next generation of smart polymeric materials. [ABSTRACT FROM AUTHOR]

Self-healing polyester elastomers with good mechanical strength, excellent toughness and rapid self-healing property were obtained by post-functionalized polyester backbone with UPy units through a thiol-ene click reaction. [Display omitted] • Self-healing polyester elastomers were obtained by post-functionalized polyester backbone with UPy units. • Elastomers show good mechanical strength, excellent elongation at break, good toughness and rapid self-healing property. • High polyester molecular weight, moderate UPy content and inhibition of crystallization are helpful to improve the mechanical and self-healing properties of elastomers. It is a desirable to prepare high performance polyester elastomers that possess high strength, good elasticity and efficient self-healing capability. Herein, we report the preparation of such elastomers based on aliphatic polyesters cross-linked by UPy-UPy quadruple hydrogen bonding. A functional monomer α-methylene-γ-butyrolactone (MBL) was copolymerized with ε-caprolactone (ε-CL) to give pendent double bonds functionalized copolyester precursors, which were subject to post-modification with UPy groups via the efficient thiol-ene click reaction. Then, the self-healing polyester elastomers were finally obtained by tuning the molecular weight of precursors, the contents of UPy units and crystallization behaviors. The results show that high polyester molecular weight, moderate UPy content and inhibition of crystallization are helpful to improve the mechanical and self-healing properties of elastomers. The obtained elastomers show good mechanical strength (1.0–1.5 MPa), excellent elongation at break (970–1560 %) and toughness (9.6–11.9 MJ/m3), and have the rapid self-healing property (>70 % after healing at 60 °C for 2 h), displaying great potential in biomedical applications. [ABSTRACT FROM AUTHOR]