An optically active rod coil rod triblock copolymer containing poly(ethylene oxide)(PEO) as the flexible segment and poly{(+) 2,5 bis[4′ ((s) 2 methyl butoxy) phenyl]styrene} (PMBPS) as the rigid segment,PMBPS b PEO ...An optically active rod coil rod triblock copolymer containing poly(ethylene oxide)(PEO) as the flexible segment and poly{(+) 2,5 bis[4′ ((s) 2 methyl butoxy) phenyl]styrene} (PMBPS) as the rigid segment,PMBPS b PEO b PMBPS,was synthesized via atom transfer radical polymerization.The PMBPS block had a stable helical conformation with an excess of screw sense in solution.The self assembly behavior of the triblock copolymer in dioxane/water mixed solvents was examined by means of TEM and turbidity measurements.The triblock copolymer molecules aggregated when water content in the system was about 2wt%. The higher the initial polymer concentrations,the lower the critical water content.They formed vesicles with highly dispersed outside diameters,but they had a relatively uniform wall thickness of (27±3) nm.展开更多
In this paper, the self-assembly of PS 43-b-PEO 45-b-PS 43 triblcok copolymer was investigated. The colloids were made by firstly dissolving the copolymer in the common solvents, including THF, 1,4-dioxane, and DMF, t...In this paper, the self-assembly of PS 43-b-PEO 45-b-PS 43 triblcok copolymer was investigated. The colloids were made by firstly dissolving the copolymer in the common solvents, including THF, 1,4-dioxane, and DMF, then droping water into the corresponding copolymer solution to induce the self-assembly. The aggregates prepared were characterized with TEM and AFM techniques. The experimental results demonstrated that the self-assembled vesicles were formed when THF and 1,4-dioxane were used as the common solvents to dissolve the copolymer, comparatively, using DMF as the common solvent resulted in the formation of spherical aggregates. The self-assembled aggregates observed, possessing hierarchical structures, could be used as either the nanostructures themselves for drug delivery systems, separations, catalysts, and so on, or templates or building blocks for more complex structures.展开更多
Biodegradable triblock copolymer PLA/PEG/PLA was synthesized by ring-opening bulk polymerization of D,L-lactide in the presence of poly(ethylene glycol) (PEG), in the molecular structure of which, the length of PEG an...Biodegradable triblock copolymer PLA/PEG/PLA was synthesized by ring-opening bulk polymerization of D,L-lactide in the presence of poly(ethylene glycol) (PEG), in the molecular structure of which, the length of PEG and PLA chain segments was made to be quite different. Nanoparticles were prepared by using the copolymer via a double emulsion-evaporation technique. The paticles tended to form the configuration like capsules, i.e., the nanocapsules, because of the great size difference in PEG and PLA segments of the copolymer. Insulin, chosen as a model drug, was encapsulated into nanocapsules. The effect of preparation conditions on the size, insulin encapsulation efficiency, and in vitro drug release behavour of the nanoparticles were investigated. The experimental results show that the nanocapsules had a smooth spherical surface and the mean diameter was in the range from 180 nm to 350 nm, and the entrapment of insulin achieved up to 78.4. The drug-loaded nanocapsules released their content continuously, remarkably different from the corresponding micelles which gave a significant initial burst release followed by a slow release.展开更多
Hydrogenation of SBS using RuCl 2(PPh 3) 3 as catalyst and PPh\-3 as ligand was studied for the first time.Hydrogenated Degree of hydrogenation of SEBS reaches 98%.RuCl 2(PPh 3) 3 which was used as catalyst has high a...Hydrogenation of SBS using RuCl 2(PPh 3) 3 as catalyst and PPh\-3 as ligand was studied for the first time.Hydrogenated Degree of hydrogenation of SEBS reaches 98%.RuCl 2(PPh 3) 3 which was used as catalyst has high activity and high selectivity (phenyl is not hydrogenated),and gel will not be formed.The band of C C was saturated.So that RuCl 2(PPh 3) 3 has high selectivity.It is shown that the thermal resistance was improved greatly by initial decomposition temperature.Rh Ru double metal new catalytic system has higher activity than Ru single metal system in hydrogenation of SBS.展开更多
A new biodegradable PtBA-PHB-PtBA triblock copolymer was successfully synthesized by ATRP method with Br-PHB-Br as macroinitiator,tert-butyl acrylate as monomer and CuBr/PMDETA as the catalyst system.Cleavage of the t...A new biodegradable PtBA-PHB-PtBA triblock copolymer was successfully synthesized by ATRP method with Br-PHB-Br as macroinitiator,tert-butyl acrylate as monomer and CuBr/PMDETA as the catalyst system.Cleavage of the tert-butyl ether groups of the PtBA-PHB-PtBA triblock copolymer was then performed via hydrolysis with trifluoroacetic acid as the catalyst in dichloromethane to afford the amphiphilic PAA-PHB-PAA triblock copolymer.The hydrolysis is successful but trace tert-butyl ether groups still remain in the backbone.The molecular weight characteristics and chain structures were conformed by GPC and NMR,respectively.Because of hydrophilic and biocompatibility,the amphiphilic triblock copolymers have potential applications in the field of drug release.展开更多
文摘An optically active rod coil rod triblock copolymer containing poly(ethylene oxide)(PEO) as the flexible segment and poly{(+) 2,5 bis[4′ ((s) 2 methyl butoxy) phenyl]styrene} (PMBPS) as the rigid segment,PMBPS b PEO b PMBPS,was synthesized via atom transfer radical polymerization.The PMBPS block had a stable helical conformation with an excess of screw sense in solution.The self assembly behavior of the triblock copolymer in dioxane/water mixed solvents was examined by means of TEM and turbidity measurements.The triblock copolymer molecules aggregated when water content in the system was about 2wt%. The higher the initial polymer concentrations,the lower the critical water content.They formed vesicles with highly dispersed outside diameters,but they had a relatively uniform wall thickness of (27±3) nm.
文摘In this paper, the self-assembly of PS 43-b-PEO 45-b-PS 43 triblcok copolymer was investigated. The colloids were made by firstly dissolving the copolymer in the common solvents, including THF, 1,4-dioxane, and DMF, then droping water into the corresponding copolymer solution to induce the self-assembly. The aggregates prepared were characterized with TEM and AFM techniques. The experimental results demonstrated that the self-assembled vesicles were formed when THF and 1,4-dioxane were used as the common solvents to dissolve the copolymer, comparatively, using DMF as the common solvent resulted in the formation of spherical aggregates. The self-assembled aggregates observed, possessing hierarchical structures, could be used as either the nanostructures themselves for drug delivery systems, separations, catalysts, and so on, or templates or building blocks for more complex structures.
文摘Biodegradable triblock copolymer PLA/PEG/PLA was synthesized by ring-opening bulk polymerization of D,L-lactide in the presence of poly(ethylene glycol) (PEG), in the molecular structure of which, the length of PEG and PLA chain segments was made to be quite different. Nanoparticles were prepared by using the copolymer via a double emulsion-evaporation technique. The paticles tended to form the configuration like capsules, i.e., the nanocapsules, because of the great size difference in PEG and PLA segments of the copolymer. Insulin, chosen as a model drug, was encapsulated into nanocapsules. The effect of preparation conditions on the size, insulin encapsulation efficiency, and in vitro drug release behavour of the nanoparticles were investigated. The experimental results show that the nanocapsules had a smooth spherical surface and the mean diameter was in the range from 180 nm to 350 nm, and the entrapment of insulin achieved up to 78.4. The drug-loaded nanocapsules released their content continuously, remarkably different from the corresponding micelles which gave a significant initial burst release followed by a slow release.
文摘Hydrogenation of SBS using RuCl 2(PPh 3) 3 as catalyst and PPh\-3 as ligand was studied for the first time.Hydrogenated Degree of hydrogenation of SEBS reaches 98%.RuCl 2(PPh 3) 3 which was used as catalyst has high activity and high selectivity (phenyl is not hydrogenated),and gel will not be formed.The band of C C was saturated.So that RuCl 2(PPh 3) 3 has high selectivity.It is shown that the thermal resistance was improved greatly by initial decomposition temperature.Rh Ru double metal new catalytic system has higher activity than Ru single metal system in hydrogenation of SBS.
文摘A new biodegradable PtBA-PHB-PtBA triblock copolymer was successfully synthesized by ATRP method with Br-PHB-Br as macroinitiator,tert-butyl acrylate as monomer and CuBr/PMDETA as the catalyst system.Cleavage of the tert-butyl ether groups of the PtBA-PHB-PtBA triblock copolymer was then performed via hydrolysis with trifluoroacetic acid as the catalyst in dichloromethane to afford the amphiphilic PAA-PHB-PAA triblock copolymer.The hydrolysis is successful but trace tert-butyl ether groups still remain in the backbone.The molecular weight characteristics and chain structures were conformed by GPC and NMR,respectively.Because of hydrophilic and biocompatibility,the amphiphilic triblock copolymers have potential applications in the field of drug release.
