Gas-phase synthesis of glycolide(GL)from methyl glycolate(MG)is of great significance for producing biodegradable polyglycolic acid.Here,we report a detailed thermodynamics study for the gas-phase synthesis of GL from...Gas-phase synthesis of glycolide(GL)from methyl glycolate(MG)is of great significance for producing biodegradable polyglycolic acid.Here,we report a detailed thermodynamics study for the gas-phase synthesis of GL from MG,which involves complex reaction pathways,by utilizing the Gibbs free energy minimization method.The results indicate that the decompositions of MG and GL and the polymerization of MG are thermodynamically favorable as compared with the target pathway,i.e.,the cyclization of MG.Effects of the reaction conditions including temperature,pressure and feed composition on the formation of GL and linear polymers have also been addressed,which demonstrate that the higher temperature and lower pressure can effectively inhibit the formation of linear methyl ester dimer and improve the selectivity to GL.In addition,the higher N_(2)/MG ratio is beneficial for the formation of GL in the process promoted by catalysts.These thermodynamics results indicate that the process promoted by catalysts would benefit from the kinetics control by high-performance catalysts and the operation at high temperature,low pressure and high N_(2)/MG ratio to enhance the yield of targeted GL.The insights demonstrated here from thermodynamics are valuable for guiding the design of catalysts and/or optimization of reaction conditions for the gas-phase synthesis of GL from MG.展开更多
For monomer reactivity ratios study, the copolymerization of D,L-3-methylglycolide (MG) with glycolide (GA) or D,L-lactide (LA) was carried out in bulk to a certain low conversion in the presence of stannous octoate a...For monomer reactivity ratios study, the copolymerization of D,L-3-methylglycolide (MG) with glycolide (GA) or D,L-lactide (LA) was carried out in bulk to a certain low conversion in the presence of stannous octoate at 140 degrees C. The copolymer compositions were determined by H-1 NMR spectroscopy. The monomer reactivity ratios were evaluated by Fineman-Ross method, Kelen-Tudos method and linear least-squares method. The monomer reactivity ratios of D,L-3-methylglycolide and glycolide or D,L-lactide are r(mg)= 0.73, r(ga)= 1.47; r(mg)= 1.71, r(la)= 0.92, respectively.展开更多
A novel polyester containing glycolic acid(GA)and 2 hydro 2 oxo 1,3,2 dioxaphosphorinane(TMP)was prepared by ring opening polymerization.The composition and the structure of the titled polymer were investigated by 1...A novel polyester containing glycolic acid(GA)and 2 hydro 2 oxo 1,3,2 dioxaphosphorinane(TMP)was prepared by ring opening polymerization.The composition and the structure of the titled polymer were investigated by 1H NMR, 13 C NMR,FT IR,EA,and VPO.The influence of time on total conversion and molecular weight was also studied.展开更多
High-purity glycolide is a key monomer for the synthesis of biodegradable polyglycolic acid.Here,we report a relay transesterification strategy for synthesizing high-purity glycolide directly from methyl glycolate,by ...High-purity glycolide is a key monomer for the synthesis of biodegradable polyglycolic acid.Here,we report a relay transesterification strategy for synthesizing high-purity glycolide directly from methyl glycolate,by using behenyl alcohol as a recyclable transesterification agent.This strategy achieves an average purity of 99.3%for glycolide without forming oligomers,and thus can avoid the energy-intensive purification required in the conventional route.Mechanistic studies indicate that methyl glycolate is first converted into behenyl glycolate via hetero-intermolecular transesterification during the relay transesterification process,and then the behenyl glycolate undergoes a homo-intermolecular transesterification to form behenyl dimer glycolate,which then undergoes intramolecular backbiting transesterification to yield glycolide and behenyl alcohol.展开更多
This paper reviewed all types of the polymer - based synthetic absorbable surgical sutures that have been commercially produced. The chemical component, biological and mechanical properties, and using effect of these ...This paper reviewed all types of the polymer - based synthetic absorbable surgical sutures that have been commercially produced. The chemical component, biological and mechanical properties, and using effect of these sutures were discussed. The recent development and the possible coming research orientation in these areas were also presented.展开更多
A micro-envioment for nerve cells and tissue growth were designed and constructed via surface modification of poly（L-lactide-co-glycolide）（PLGA） with chitosan and hydroxyapatire（HA）. The poly（L_lactide-co-glyco...A micro-envioment for nerve cells and tissue growth were designed and constructed via surface modification of poly（L-lactide-co-glycolide）（PLGA） with chitosan and hydroxyapatire（HA）. The poly（L_lactide-co-glycolide）/chitosan/hydroxyapatite （PLGA/chitosan/HA） conduits were manufactured by a combined solvent casting and particulate leaching technique. The conduits were highly porous with an interconnected pore structure and 76.5% porosity. Micropores with 50-100 micrometer diameter were formed in the conduits. In vivo application of PLGA/chitosan/HA conduits for reconstruction of 10 mm sciatic nerve defect was assessed by the walking track analysis, the quantifying of the wet weight of tibialis anterior muscle and the histological assessment. The conduits in host rats in vivo can not only be an effective in promoting regenerating of nerves but can also lead to favorable nerve functional recovery.展开更多
Biodegradable poly(alc-alt-Asp)was synthesized by ring-opening polymerization of the monomer 3-(S)-[(benzyloxycarbonyl)methyl]-morpholine-2,5-dione and subsequent catalytic hydrogenation.Copolymers of the monomer with...Biodegradable poly(alc-alt-Asp)was synthesized by ring-opening polymerization of the monomer 3-(S)-[(benzyloxycarbonyl)methyl]-morpholine-2,5-dione and subsequent catalytic hydrogenation.Copolymers of the monomer with glycolide,D,L-lactide and L-lactide were also prepared.展开更多
基金supported by the National Natural Science Foundation of China(22478106,22178102,and 22332003)Shanghai Rising-Star Program(23QA1401900)+1 种基金Young Elite Scientists Sponsorship Programby CAST(2023QNRC001)the Open Project of Yunnan Precious Metals Laboratory Co.,Ltd(YPML-2023050272).
文摘Gas-phase synthesis of glycolide(GL)from methyl glycolate(MG)is of great significance for producing biodegradable polyglycolic acid.Here,we report a detailed thermodynamics study for the gas-phase synthesis of GL from MG,which involves complex reaction pathways,by utilizing the Gibbs free energy minimization method.The results indicate that the decompositions of MG and GL and the polymerization of MG are thermodynamically favorable as compared with the target pathway,i.e.,the cyclization of MG.Effects of the reaction conditions including temperature,pressure and feed composition on the formation of GL and linear polymers have also been addressed,which demonstrate that the higher temperature and lower pressure can effectively inhibit the formation of linear methyl ester dimer and improve the selectivity to GL.In addition,the higher N_(2)/MG ratio is beneficial for the formation of GL in the process promoted by catalysts.These thermodynamics results indicate that the process promoted by catalysts would benefit from the kinetics control by high-performance catalysts and the operation at high temperature,low pressure and high N_(2)/MG ratio to enhance the yield of targeted GL.The insights demonstrated here from thermodynamics are valuable for guiding the design of catalysts and/or optimization of reaction conditions for the gas-phase synthesis of GL from MG.
基金This work was supported by the Key Project of the National Natural Science Foundation of China!(59833 140).
文摘For monomer reactivity ratios study, the copolymerization of D,L-3-methylglycolide (MG) with glycolide (GA) or D,L-lactide (LA) was carried out in bulk to a certain low conversion in the presence of stannous octoate at 140 degrees C. The copolymer compositions were determined by H-1 NMR spectroscopy. The monomer reactivity ratios were evaluated by Fineman-Ross method, Kelen-Tudos method and linear least-squares method. The monomer reactivity ratios of D,L-3-methylglycolide and glycolide or D,L-lactide are r(mg)= 0.73, r(ga)= 1.47; r(mg)= 1.71, r(la)= 0.92, respectively.
文摘A novel polyester containing glycolic acid(GA)and 2 hydro 2 oxo 1,3,2 dioxaphosphorinane(TMP)was prepared by ring opening polymerization.The composition and the structure of the titled polymer were investigated by 1H NMR, 13 C NMR,FT IR,EA,and VPO.The influence of time on total conversion and molecular weight was also studied.
基金supported by the Natural Science Foundation of China(Grant No.22478106).
文摘High-purity glycolide is a key monomer for the synthesis of biodegradable polyglycolic acid.Here,we report a relay transesterification strategy for synthesizing high-purity glycolide directly from methyl glycolate,by using behenyl alcohol as a recyclable transesterification agent.This strategy achieves an average purity of 99.3%for glycolide without forming oligomers,and thus can avoid the energy-intensive purification required in the conventional route.Mechanistic studies indicate that methyl glycolate is first converted into behenyl glycolate via hetero-intermolecular transesterification during the relay transesterification process,and then the behenyl glycolate undergoes a homo-intermolecular transesterification to form behenyl dimer glycolate,which then undergoes intramolecular backbiting transesterification to yield glycolide and behenyl alcohol.
文摘This paper reviewed all types of the polymer - based synthetic absorbable surgical sutures that have been commercially produced. The chemical component, biological and mechanical properties, and using effect of these sutures were discussed. The recent development and the possible coming research orientation in these areas were also presented.
基金Funded by the National Natural Science Foundation of China(No.50774096)
文摘A micro-envioment for nerve cells and tissue growth were designed and constructed via surface modification of poly（L-lactide-co-glycolide）（PLGA） with chitosan and hydroxyapatire（HA）. The poly（L_lactide-co-glycolide）/chitosan/hydroxyapatite （PLGA/chitosan/HA） conduits were manufactured by a combined solvent casting and particulate leaching technique. The conduits were highly porous with an interconnected pore structure and 76.5% porosity. Micropores with 50-100 micrometer diameter were formed in the conduits. In vivo application of PLGA/chitosan/HA conduits for reconstruction of 10 mm sciatic nerve defect was assessed by the walking track analysis, the quantifying of the wet weight of tibialis anterior muscle and the histological assessment. The conduits in host rats in vivo can not only be an effective in promoting regenerating of nerves but can also lead to favorable nerve functional recovery.
基金supported by the National Natural Science Foundation of China.
文摘Biodegradable poly(alc-alt-Asp)was synthesized by ring-opening polymerization of the monomer 3-(S)-[(benzyloxycarbonyl)methyl]-morpholine-2,5-dione and subsequent catalytic hydrogenation.Copolymers of the monomer with glycolide,D,L-lactide and L-lactide were also prepared.
