The reaction mechanism, reactivities, and apparent activation energies of epoxy/dicyanamide curing system accelerated by C6H5NHCONR2 (R=CH3, n-C4H9, i-C3H7,) werestudied by DSC and GC techniques. The results showed th...The reaction mechanism, reactivities, and apparent activation energies of epoxy/dicyanamide curing system accelerated by C6H5NHCONR2 (R=CH3, n-C4H9, i-C3H7,) werestudied by DSC and GC techniques. The results showed that in reaction of C6H5,NHCONR2with either dicyanamide or epoxy resin there was a dimethylamine released reacting with epoxy resin, giving a tertiary amine, which accelerated the anionic homopolymerization of epoxy resin.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
文摘The reaction mechanism, reactivities, and apparent activation energies of epoxy/dicyanamide curing system accelerated by C6H5NHCONR2 (R=CH3, n-C4H9, i-C3H7,) werestudied by DSC and GC techniques. The results showed that in reaction of C6H5,NHCONR2with either dicyanamide or epoxy resin there was a dimethylamine released reacting with epoxy resin, giving a tertiary amine, which accelerated the anionic homopolymerization of epoxy resin.
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.
