Polyesters,as a class of high-performance and versatile polymer materials,often suffer from some drawbacks,such as hydrophobicity and brittleness due to their single structure nature.Thus,modifications have attracted ...Polyesters,as a class of high-performance and versatile polymer materials,often suffer from some drawbacks,such as hydrophobicity and brittleness due to their single structure nature.Thus,modifications have attracted much attention for enhancing their desirable properties,of which one efficient way is incorporating the aliphatic polyether segment into the main chain of the polyester.However,this approach is of much challenge because the obtained polyesters are problematic in either low alternating degree or low molecular weight.Herein,we describe an efficient strategy to incorporate polyether fragment into polyester by developing a novel Co-Al based heterodinuclear complex for mediating the copolymerization of propylene oxide(PO)withε-caprolactone(CL).The tracking experiments reveal that PO and CL convert into the polymer chain throughout the polymerization process.Especially,the linear increase in the molecular weight with conversion of CL indicates the controllable nature of the copolymerization.The competition polymerization,offering the monomer reactivity ratios of rCL=0.96 and rPO=1.04,suggests that the tendency of self-propagation or incorporation of monomers is nearly identical.interestingly,the obtained polymers with different ether contents exhibit tunable thermal properties with enhanced decomposition temperature for the polymer with higher ether content.The newly developed heterodinuclear complex for new polymerization provides an idea to synthesize new functional polymeric materials.展开更多
The random ring-opening terpolymerization of CO_(2),epoxides,and lactones remains challenging,mainly because CO_(2)/epoxide copolymerization and lactone ring-opening polymerization typically proceed at very different ...The random ring-opening terpolymerization of CO_(2),epoxides,and lactones remains challenging,mainly because CO_(2)/epoxide copolymerization and lactone ring-opening polymerization typically proceed at very different rates.Herein,we report the preparation of novel statistical terpolymers with random distributions of carbonate and ester units(up to 40%junction units)via the one-pot reaction ofβ-propiolactone(BPL),epoxides,and CO_(2) under mild conditions using a binary catalyst system consisting of SalcyCo(III)OTs(Salcy=N,N′-bis(3,5-di-tert-butylsalicylidene)-1,2-diaminocyclohexane;OTs=p-toluenesulfonate)and 7-methyl-1,5,7-triazabicyclo[4.4.0]dec-5-ene.Since this catalytic system could yield similar reaction rates for alternating epoxide/CO_(2) copolymerization and BPL polymerization,terpolymers with nearly identical compositions were produced at various time points.CO_(2) played an important role in preventing intra-and/or intermolecular transesterification side reactions.Thereby,the terpolymerization proceeded in a controlled manner,allowing for the fine-tuning of molecular weight and composition.Two-dimensional nuclear magnetic resonance(NMR)analysis and density functional theory(DFT)calculations suggested that the nucleophilic attack of the coordinated BPL by carbonate ions cleaved the alkyl C–O bond predominantly rather than the acyl C(=O)–O bond,typically observable during the nucleophilic ring-opening polymerization of BPL.These findings have opened up a new avenue for preparing a broad family of biodegradable polymers with adjustable properties.展开更多
基金the National Natural Science Foundation of China(Nos.21722402 and 21674015)the Fundamental Research Funds for the Central Universities(No.DUT18ZD105).
文摘Polyesters,as a class of high-performance and versatile polymer materials,often suffer from some drawbacks,such as hydrophobicity and brittleness due to their single structure nature.Thus,modifications have attracted much attention for enhancing their desirable properties,of which one efficient way is incorporating the aliphatic polyether segment into the main chain of the polyester.However,this approach is of much challenge because the obtained polyesters are problematic in either low alternating degree or low molecular weight.Herein,we describe an efficient strategy to incorporate polyether fragment into polyester by developing a novel Co-Al based heterodinuclear complex for mediating the copolymerization of propylene oxide(PO)withε-caprolactone(CL).The tracking experiments reveal that PO and CL convert into the polymer chain throughout the polymerization process.Especially,the linear increase in the molecular weight with conversion of CL indicates the controllable nature of the copolymerization.The competition polymerization,offering the monomer reactivity ratios of rCL=0.96 and rPO=1.04,suggests that the tendency of self-propagation or incorporation of monomers is nearly identical.interestingly,the obtained polymers with different ether contents exhibit tunable thermal properties with enhanced decomposition temperature for the polymer with higher ether content.The newly developed heterodinuclear complex for new polymerization provides an idea to synthesize new functional polymeric materials.
基金supported by the National Natural Science Foundation of China(NSFCgrant nos.21690073 and 21920102006)the Program for Changjiang Scholars and Innovative Research Team in University(IRT-17R14).
文摘The random ring-opening terpolymerization of CO_(2),epoxides,and lactones remains challenging,mainly because CO_(2)/epoxide copolymerization and lactone ring-opening polymerization typically proceed at very different rates.Herein,we report the preparation of novel statistical terpolymers with random distributions of carbonate and ester units(up to 40%junction units)via the one-pot reaction ofβ-propiolactone(BPL),epoxides,and CO_(2) under mild conditions using a binary catalyst system consisting of SalcyCo(III)OTs(Salcy=N,N′-bis(3,5-di-tert-butylsalicylidene)-1,2-diaminocyclohexane;OTs=p-toluenesulfonate)and 7-methyl-1,5,7-triazabicyclo[4.4.0]dec-5-ene.Since this catalytic system could yield similar reaction rates for alternating epoxide/CO_(2) copolymerization and BPL polymerization,terpolymers with nearly identical compositions were produced at various time points.CO_(2) played an important role in preventing intra-and/or intermolecular transesterification side reactions.Thereby,the terpolymerization proceeded in a controlled manner,allowing for the fine-tuning of molecular weight and composition.Two-dimensional nuclear magnetic resonance(NMR)analysis and density functional theory(DFT)calculations suggested that the nucleophilic attack of the coordinated BPL by carbonate ions cleaved the alkyl C–O bond predominantly rather than the acyl C(=O)–O bond,typically observable during the nucleophilic ring-opening polymerization of BPL.These findings have opened up a new avenue for preparing a broad family of biodegradable polymers with adjustable properties.
