The asymmetric alternating copolymerization of meso-epoxide and cyclic anhydrides provides an efficient access to enantiopure polyesters.Contrary to the extensive investigation of the stereochemistry resulting from ep...The asymmetric alternating copolymerization of meso-epoxide and cyclic anhydrides provides an efficient access to enantiopure polyesters.Contrary to the extensive investigation of the stereochemistry resulting from epoxide building block,the chirality from anhydride and the configurational match with epoxide remain elusive.Herein,we discover that the bimetallic chromium catalysts have led to an obvious enhancement in terms of reactivity and enantioselectivity for the asymmetric copolymerization of meso-epoxide with various non-symmetric chiral anhydrides.Up to 97%ee was obtained during the asymmetric copolymerization of cyclohexene oxide(CHO)with(R)-methylsuccinic anhydride(R-MSA),and three-or four-carbon chiral centers were simultaneously installed in the aliphatic polyester backbone.In particular,the different combinations of stereochemistry in epoxide and anhydride building blocks considerably affect the thermal properties and crystalline behaviors of the resulting polyesters.This study uncovers an interesting method for regulating polymer crystallinity via matching the chirality of different monomers.展开更多
Aliphatic polyesters were synthesized via the ring opening polymerization of the corresponding lactones initiated with dibutylmagnesium both in bulk and in solution. The resulting polymers were characterized by 1H, 13...Aliphatic polyesters were synthesized via the ring opening polymerization of the corresponding lactones initiated with dibutylmagnesium both in bulk and in solution. The resulting polymers were characterized by 1H, 13C NMR, GPC and XRD. The results indicated that dibutylmagnesium is an effective initiator for the ring opening polymerization of lactones.展开更多
Eggshell powder is a powdered product that is made from discarded eggshells. It is rich in inorganic salts and a small number of organic substances. Aliphatic polyester is one of the most promising polymer materials a...Eggshell powder is a powdered product that is made from discarded eggshells. It is rich in inorganic salts and a small number of organic substances. Aliphatic polyester is one of the most promising polymer materials at present. Aliphatic polyester has not only a wide range of sources, but also excellent biodegradability and biocompatibility. Three kinds of aliphatic polyester composites were mixed with PCL, PBS, PHA, PLA and Ag powder as raw materials through solution reinforcement by eggshell powder. The thermal properties and structures of the three materials were analyzed and characterized by differential scanning calorimetry and scanning electron microscopy. DSC and SEM were used to analyze and characterize the thermal properties and structures of the three composites. The experimental results show that the GTT(glass-transition temperature) are 91.9°C, 89.3°C, and 87.2°C, the melting points are all greater than 92°C, and the enthalpy changes are respectively -37.8J/g, -23.9J/g, -22.2 J/g,. Among them, the composite material of PCL, PBS and eggshell powder, and Ag powder has excellent performance, showing good thermal performance and thermal stability. Moreover, the production and utilization of eggshell powder, turning waste into wealth, has important economic value for the sustainable development of circular ecology.展开更多
Copolymerization as an efficient strategy can provide an opportunity to create new closed-loop recyclable polymeric materials with tailored properties that are generally inaccessible to the individual homopolymers.In ...Copolymerization as an efficient strategy can provide an opportunity to create new closed-loop recyclable polymeric materials with tailored properties that are generally inaccessible to the individual homopolymers.In this contribution,the bulk ring-opening copolymerization of bio-renewable-caprolactone and trans-hexahydro-(4,5)-benzofuranone was achieved to produce closed-loop recyclable copolyesters by using an organobase/urea binary catalyst at room temperature.The obtained copolyesters exhibited composition-dependent thermal properties.Remarkably,the obtained copolyesters were able to depolymerize back to recover the corresponding monomers under mild conditions.展开更多
We present here the first synthesis of cyclic oligo（ethylene adipate）s （COEAs） via pseudo-high dilution condensation reaction of adipoyl chloride with ethylene glycol, and the synthesis of corresponding poly（ethy...We present here the first synthesis of cyclic oligo（ethylene adipate）s （COEAs） via pseudo-high dilution condensation reaction of adipoyl chloride with ethylene glycol, and the synthesis of corresponding poly（ethylene adipate） （PEA） via the melt polymerization of COEAs. The structure of COEAs was characterized and proved by 1H-NMR and MALDI-TOF mass measurements. The effects of organic base, reaction temperature and the ratio of adipoyl chloride to ethylene glycol on the yield of COEAs were studied, and the optimum reaction condition was revealed. PEA, a diacid and diol based semi-crystalline green aliphatic polyester, was synthesized by the melt polymerization of COEAs using Ti（n-C4H90）4 as catalyst and 1,10-decanediol as initiator at 200 ℃, which follows the polycondensation-coupling ring- opening polymerization method. Our strategy should be applicable to the synthesis of versatile aliphatic polyesters based on diacid and diol monomers, which have potential applications as biocompatible and biodegradable materials.展开更多
Novel biodegradable aliphatic polyesters,poly（butylene succinate-co-triethylene glycol succinate）（P（BS-co-TEGS））and poly（butylene succinate）（PBS）,were synthesized through a two-step procedure of esterificati...Novel biodegradable aliphatic polyesters,poly（butylene succinate-co-triethylene glycol succinate）（P（BS-co-TEGS））and poly（butylene succinate）（PBS）,were synthesized through a two-step procedure of esterification and polycondensation with succinic acid and1,4-butanediol/triethylene glycol as raw materials as well as tetrabutyl titanate and diphenylphosphinic acid as the co-catalysts.The chemical structure and molecular weight of the copolymers were characterized by 1^H nuclear magnetic resonance（1^H NMR）and gel permeation chromatography（GPC）,respectively.In addition,thermal properties,crystal structure and mechanical properties were also analyzed with various techniques.P（BS-co-TEGS）exhibited more excellent mechanical properties than PBS,especially in elongation at break.Meanwhile,the crystal structure and thermal stability of the P（BS-co-TEGS）have hardly changed.The crystallinity of P（BS-co-TEGS）was lower than that of PBS and decreased with the increase of mole ratio of triethylene glycol.With the increase of TEGS unit molar composition,the melting point（Tm）,crystallization temperatures（Tc）and heat of fusion（ΔHm）of P（BS-co-TEGS）decreased,while glass transition temperature（Tg）increased.展开更多
Poly(lactic acid) and its copolymers are regarded as the most useful biomaterials. The good biocompatibility, biodegradability and mechanical properties of them make the synthetic biodegradable polymers have primary...Poly(lactic acid) and its copolymers are regarded as the most useful biomaterials. The good biocompatibility, biodegradability and mechanical properties of them make the synthetic biodegradable polymers have primary application to tissue engineering. The advantages and disadvantages of the synthetic biodegradable polymers as cell scaffold materials are evaluated. This article reviews the modification of polylactide-family aliphatic polymers to improve the cell affinity when the polymers are used as cell scaffolds. We have developed four main approaches: to modify polyester cell scaffolds in combination of plasma treating and collagen coating; to introduce hydrophilic segments into aliphatic polyester backbones; to introduce pendant functional groups into polyester chains; to modify polyester with dextran. The results of the cell cultures prove that the approaches mentioned above have improved the cell affinity of the polyesters and have modulated cell function such as adhesion, proliferation and migration.展开更多
Aliphatic biodegradable polyesters have been the most widely used synthetic polymers for developing biodegradable devices as alternatives for the currently used permanent medical devices.The performances during biodeg...Aliphatic biodegradable polyesters have been the most widely used synthetic polymers for developing biodegradable devices as alternatives for the currently used permanent medical devices.The performances during biodegradation process play crucial roles for final realization of their functions.Because physiological and biochemical environment in vivo significantly affects biodegradation process,large numbers of studies on effects of mechanical loads on the degradation of aliphatic biodegradable polyesters have been launched during last decades.In this review article,we discussed the mechanism of biodegradation and several different mechanical loads that have been reported to affect the biodegradation process.Other physiological and biochemical factors related to mechanical loads were also discussed.The mechanical load could change the conformational strain energy and morphology to weaken the stability of the polymer.Besides,the load and pattern could accelerate the loss of intrinsic mechanical properties of polymers.This indicated that investigations into effects of mechanical loads on the degradation should be indispensable.More combination condition of mechanical loads and multiple factors should be considered in order to keep the degradation rate controllable and evaluate the degradation process in vivo accurately.Only then can the degradable devise achieve the desired effects and further expand the special applications of aliphatic biodegradable polyesters.展开更多
Rare earth tris(2,6-di-tert-butyl-4-methylphenolate) [Ln-(OAr)3, Ln = La, Nd, Dy, Y] alone has been developed to initiate polymerization of e-caprolactone (CL) and random copolymerization of CL with 2, 2-dimethyltrime...Rare earth tris(2,6-di-tert-butyl-4-methylphenolate) [Ln-(OAr)3, Ln = La, Nd, Dy, Y] alone has been developed to initiate polymerization of e-caprolactone (CL) and random copolymerization of CL with 2, 2-dimethyltrimethylene carbonate (DTC). The structures of polymers were analyzed by GPC, ER and NMR methods. Their crystal and thermal properties were discussed in terms of DSC. The initiating efficiencies were mainly affected by the size of rare earth metal in the sequence of La(OAr)3 > Nd(OAr)3 ～ Y(OAr)3 > Dy(OAr)3. La-(OAr)3 exhibited rather high activity to prepare PCL with a molecular weight of 2.15 × 105 and Ma/Ma of 2.27. The composition of random copolymer can be quantitatively controlled either by reaction time or by feed ratio of monomer.展开更多
基金financially supported by the National Natural Science Foundation of China(Nos.22071016 and 21920102006)。
文摘The asymmetric alternating copolymerization of meso-epoxide and cyclic anhydrides provides an efficient access to enantiopure polyesters.Contrary to the extensive investigation of the stereochemistry resulting from epoxide building block,the chirality from anhydride and the configurational match with epoxide remain elusive.Herein,we discover that the bimetallic chromium catalysts have led to an obvious enhancement in terms of reactivity and enantioselectivity for the asymmetric copolymerization of meso-epoxide with various non-symmetric chiral anhydrides.Up to 97%ee was obtained during the asymmetric copolymerization of cyclohexene oxide(CHO)with(R)-methylsuccinic anhydride(R-MSA),and three-or four-carbon chiral centers were simultaneously installed in the aliphatic polyester backbone.In particular,the different combinations of stereochemistry in epoxide and anhydride building blocks considerably affect the thermal properties and crystalline behaviors of the resulting polyesters.This study uncovers an interesting method for regulating polymer crystallinity via matching the chirality of different monomers.
文摘Aliphatic polyesters were synthesized via the ring opening polymerization of the corresponding lactones initiated with dibutylmagnesium both in bulk and in solution. The resulting polymers were characterized by 1H, 13C NMR, GPC and XRD. The results indicated that dibutylmagnesium is an effective initiator for the ring opening polymerization of lactones.
文摘Eggshell powder is a powdered product that is made from discarded eggshells. It is rich in inorganic salts and a small number of organic substances. Aliphatic polyester is one of the most promising polymer materials at present. Aliphatic polyester has not only a wide range of sources, but also excellent biodegradability and biocompatibility. Three kinds of aliphatic polyester composites were mixed with PCL, PBS, PHA, PLA and Ag powder as raw materials through solution reinforcement by eggshell powder. The thermal properties and structures of the three materials were analyzed and characterized by differential scanning calorimetry and scanning electron microscopy. DSC and SEM were used to analyze and characterize the thermal properties and structures of the three composites. The experimental results show that the GTT(glass-transition temperature) are 91.9°C, 89.3°C, and 87.2°C, the melting points are all greater than 92°C, and the enthalpy changes are respectively -37.8J/g, -23.9J/g, -22.2 J/g,. Among them, the composite material of PCL, PBS and eggshell powder, and Ag powder has excellent performance, showing good thermal performance and thermal stability. Moreover, the production and utilization of eggshell powder, turning waste into wealth, has important economic value for the sustainable development of circular ecology.
基金support by National Natural Science Foundation of China(Nos.52322304,22075160 and 22031005)Taishan Scholar Foundation of Shandong Province(No.tsqn202103078).
文摘Copolymerization as an efficient strategy can provide an opportunity to create new closed-loop recyclable polymeric materials with tailored properties that are generally inaccessible to the individual homopolymers.In this contribution,the bulk ring-opening copolymerization of bio-renewable-caprolactone and trans-hexahydro-(4,5)-benzofuranone was achieved to produce closed-loop recyclable copolyesters by using an organobase/urea binary catalyst at room temperature.The obtained copolyesters exhibited composition-dependent thermal properties.Remarkably,the obtained copolyesters were able to depolymerize back to recover the corresponding monomers under mild conditions.
基金the National Natural Science Foundation of China(No.21474067)the Priority Academic Program Development of Jiangsu Higher Education Institutions
文摘We present here the first synthesis of cyclic oligo（ethylene adipate）s （COEAs） via pseudo-high dilution condensation reaction of adipoyl chloride with ethylene glycol, and the synthesis of corresponding poly（ethylene adipate） （PEA） via the melt polymerization of COEAs. The structure of COEAs was characterized and proved by 1H-NMR and MALDI-TOF mass measurements. The effects of organic base, reaction temperature and the ratio of adipoyl chloride to ethylene glycol on the yield of COEAs were studied, and the optimum reaction condition was revealed. PEA, a diacid and diol based semi-crystalline green aliphatic polyester, was synthesized by the melt polymerization of COEAs using Ti（n-C4H90）4 as catalyst and 1,10-decanediol as initiator at 200 ℃, which follows the polycondensation-coupling ring- opening polymerization method. Our strategy should be applicable to the synthesis of versatile aliphatic polyesters based on diacid and diol monomers, which have potential applications as biocompatible and biodegradable materials.
基金Supported by Anhui Sealong Biotechnology Co.,Ltd(China)
文摘Novel biodegradable aliphatic polyesters,poly（butylene succinate-co-triethylene glycol succinate）（P（BS-co-TEGS））and poly（butylene succinate）（PBS）,were synthesized through a two-step procedure of esterification and polycondensation with succinic acid and1,4-butanediol/triethylene glycol as raw materials as well as tetrabutyl titanate and diphenylphosphinic acid as the co-catalysts.The chemical structure and molecular weight of the copolymers were characterized by 1^H nuclear magnetic resonance（1^H NMR）and gel permeation chromatography（GPC）,respectively.In addition,thermal properties,crystal structure and mechanical properties were also analyzed with various techniques.P（BS-co-TEGS）exhibited more excellent mechanical properties than PBS,especially in elongation at break.Meanwhile,the crystal structure and thermal stability of the P（BS-co-TEGS）have hardly changed.The crystallinity of P（BS-co-TEGS）was lower than that of PBS and decreased with the increase of mole ratio of triethylene glycol.With the increase of TEGS unit molar composition,the melting point（Tm）,crystallization temperatures（Tc）and heat of fusion（ΔHm）of P（BS-co-TEGS）decreased,while glass transition temperature（Tg）increased.
基金Supported by the Major State Basic Research Development Program (No.G1990 5 4 30 5 )
文摘Poly(lactic acid) and its copolymers are regarded as the most useful biomaterials. The good biocompatibility, biodegradability and mechanical properties of them make the synthetic biodegradable polymers have primary application to tissue engineering. The advantages and disadvantages of the synthetic biodegradable polymers as cell scaffold materials are evaluated. This article reviews the modification of polylactide-family aliphatic polymers to improve the cell affinity when the polymers are used as cell scaffolds. We have developed four main approaches: to modify polyester cell scaffolds in combination of plasma treating and collagen coating; to introduce hydrophilic segments into aliphatic polyester backbones; to introduce pendant functional groups into polyester chains; to modify polyester with dextran. The results of the cell cultures prove that the approaches mentioned above have improved the cell affinity of the polyesters and have modulated cell function such as adhesion, proliferation and migration.
基金This work was supported by the National Key Technology R&D Program(Nos.2014BAI11B02,2014BAI11B03,2012BAI18B01)National Natural Science Foundation of China(Nos.11120101001,11421202,31370959,11572029,31470915)+3 种基金National key research and development program in China(No.2016YFC1100704,2016YFC1102202,2016YFC1101100)Beijing Nova Programme Interdisciplinary Cooperation Project(No.xxjc201616)Key Laboratory of Advanced Materials of Ministry of Education of China(Tsinghua University),Fok Ying Tung Education Foundation(No.141039)International Joint Research Center of Aerospace Biotechnology and Medical Engineering,Ministry of Science and Technology of China,and the 111 Project(No.B13003).
文摘Aliphatic biodegradable polyesters have been the most widely used synthetic polymers for developing biodegradable devices as alternatives for the currently used permanent medical devices.The performances during biodegradation process play crucial roles for final realization of their functions.Because physiological and biochemical environment in vivo significantly affects biodegradation process,large numbers of studies on effects of mechanical loads on the degradation of aliphatic biodegradable polyesters have been launched during last decades.In this review article,we discussed the mechanism of biodegradation and several different mechanical loads that have been reported to affect the biodegradation process.Other physiological and biochemical factors related to mechanical loads were also discussed.The mechanical load could change the conformational strain energy and morphology to weaken the stability of the polymer.Besides,the load and pattern could accelerate the loss of intrinsic mechanical properties of polymers.This indicated that investigations into effects of mechanical loads on the degradation should be indispensable.More combination condition of mechanical loads and multiple factors should be considered in order to keep the degradation rate controllable and evaluate the degradation process in vivo accurately.Only then can the degradable devise achieve the desired effects and further expand the special applications of aliphatic biodegradable polyesters.
文摘Rare earth tris(2,6-di-tert-butyl-4-methylphenolate) [Ln-(OAr)3, Ln = La, Nd, Dy, Y] alone has been developed to initiate polymerization of e-caprolactone (CL) and random copolymerization of CL with 2, 2-dimethyltrimethylene carbonate (DTC). The structures of polymers were analyzed by GPC, ER and NMR methods. Their crystal and thermal properties were discussed in terms of DSC. The initiating efficiencies were mainly affected by the size of rare earth metal in the sequence of La(OAr)3 > Nd(OAr)3 ～ Y(OAr)3 > Dy(OAr)3. La-(OAr)3 exhibited rather high activity to prepare PCL with a molecular weight of 2.15 × 105 and Ma/Ma of 2.27. The composition of random copolymer can be quantitatively controlled either by reaction time or by feed ratio of monomer.
