The closed-loop recycling concept of the polymer wastes into building-block chemicals is attractive,but the closed-loop recycling of copolymers enabled by energy-efficient chemical recycling and cost-effective separat...The closed-loop recycling concept of the polymer wastes into building-block chemicals is attractive,but the closed-loop recycling of copolymers enabled by energy-efficient chemical recycling and cost-effective separations is still facing great challenges.Herein,for the first time,a one-pot sequential copolymerization of γ-butyrolactone(γ-BL) and p-dioxanone(PDO)using an economical ureas/alkoxides catalytic system is conducted to synthesize biodegradable and chemically recyclable poly-(γ-butyrolactone)-block-poly(p-dioxanone)(PγBL-b-PPDO) diblock copolymers with well-defined and controlled structures.The composition-dependent properties of PγBL-b-PPDO copolymers,including thermal properties and crystallization behavior,are investigated.The results show that the thermal stability and crystalline ability of PγBL are enhanced observably by introducing the PPDO block.Significantly,the PγBL-b-PPDO copolymers can be depolymerized efficiently into the corresponding co-monomers with a yield of over 95% by simply low-temperature pyrolysis under vacuum.Moreover,γ-BL and PDO monomers are selectively separated with an isolated purity of about 99% based on the difference in their physicochemical properties.Subsequently,their repolymerization is realized to obtain the copolymers with nearly identical structures and thermostability,demonstrating the closed-loop recycling of copolymers,i.e.,polymerization-depolymerization-repolymerization.This research provides important guidance for the design of novel sustainable polymers towards more efficient chemical recycling,separation and regeneration.展开更多
Herein, we presented a novel biodegradable copolymer via the chain extending reaction of poly(pdioxanone)-co-poly(2-(2-hydroxyethoxy) benzoate)(PPDO-co-PDHB) prepolymer with hexamethylene diisocyanate(HDI) as a chain ...Herein, we presented a novel biodegradable copolymer via the chain extending reaction of poly(pdioxanone)-co-poly(2-(2-hydroxyethoxy) benzoate)(PPDO-co-PDHB) prepolymer with hexamethylene diisocyanate(HDI) as a chain extender. The structures and molecular weight of PPDO-co-PDHB prepolymer and PPDO-co-PDHB-PU chain-extended copolymer are characterized via hydrogen nuclear magnetic resonance spectroscopy(1 H NMR) and viscosity test. The relationship between the molecular structures and properties of the chain-extended copolymers is established. The PPDO-co-PDHB-PU copolymers possess a better thermal stability comparing with the PPDO homopolymer. The study of mechanical properties shows that the elongation-at-break of PPDO-co-PDHB-PU is much higher than that of PPDO. The investigation of hydrolytic degradation behaviors indicates the degradation rate of PPDO can be controlled by adjusting the PDHB compositions, and proves that chain-extended copolymers exhibit an excellent hydrolytic stability being better than that of PPDO.展开更多
基金supported by the National Key R&D Program of China (2016YFC1100702)the National Natural Science Foundation of China (U19A2095)+1 种基金the Sichuan Science and Technology Program (2017SZDZX0015)the Fundamental Research Funds for the Central Universities。
文摘The closed-loop recycling concept of the polymer wastes into building-block chemicals is attractive,but the closed-loop recycling of copolymers enabled by energy-efficient chemical recycling and cost-effective separations is still facing great challenges.Herein,for the first time,a one-pot sequential copolymerization of γ-butyrolactone(γ-BL) and p-dioxanone(PDO)using an economical ureas/alkoxides catalytic system is conducted to synthesize biodegradable and chemically recyclable poly-(γ-butyrolactone)-block-poly(p-dioxanone)(PγBL-b-PPDO) diblock copolymers with well-defined and controlled structures.The composition-dependent properties of PγBL-b-PPDO copolymers,including thermal properties and crystallization behavior,are investigated.The results show that the thermal stability and crystalline ability of PγBL are enhanced observably by introducing the PPDO block.Significantly,the PγBL-b-PPDO copolymers can be depolymerized efficiently into the corresponding co-monomers with a yield of over 95% by simply low-temperature pyrolysis under vacuum.Moreover,γ-BL and PDO monomers are selectively separated with an isolated purity of about 99% based on the difference in their physicochemical properties.Subsequently,their repolymerization is realized to obtain the copolymers with nearly identical structures and thermostability,demonstrating the closed-loop recycling of copolymers,i.e.,polymerization-depolymerization-repolymerization.This research provides important guidance for the design of novel sustainable polymers towards more efficient chemical recycling,separation and regeneration.
基金supported by the National Natural Science Foundation of China (No. U19A2095)the Sichuan Science and Technology Program (No. 2017SZDZX0015)the Fundamental Research Funds for the Central Universities。
文摘Herein, we presented a novel biodegradable copolymer via the chain extending reaction of poly(pdioxanone)-co-poly(2-(2-hydroxyethoxy) benzoate)(PPDO-co-PDHB) prepolymer with hexamethylene diisocyanate(HDI) as a chain extender. The structures and molecular weight of PPDO-co-PDHB prepolymer and PPDO-co-PDHB-PU chain-extended copolymer are characterized via hydrogen nuclear magnetic resonance spectroscopy(1 H NMR) and viscosity test. The relationship between the molecular structures and properties of the chain-extended copolymers is established. The PPDO-co-PDHB-PU copolymers possess a better thermal stability comparing with the PPDO homopolymer. The study of mechanical properties shows that the elongation-at-break of PPDO-co-PDHB-PU is much higher than that of PPDO. The investigation of hydrolytic degradation behaviors indicates the degradation rate of PPDO can be controlled by adjusting the PDHB compositions, and proves that chain-extended copolymers exhibit an excellent hydrolytic stability being better than that of PPDO.