Monodisperse poly（poly（ethyleneglycol） methyl ether acrylate-co-acrylic acid） （poly（PEGMA-co-AA）） microspheres were prepared by distillation-precipitation polymerization with divinylbenzene （DVB） as crosslin...Monodisperse poly（poly（ethyleneglycol） methyl ether acrylate-co-acrylic acid） （poly（PEGMA-co-AA）） microspheres were prepared by distillation-precipitation polymerization with divinylbenzene （DVB） as crosslinker with 2,2＇- azobisisobutyronitrile （AIBN） as initiator in neat acetonitrile without stirring. Under various reaction conditions, four distinct morphologies including the sol, microemulsion, microgels and microspheres were formed during the distillation of the solvent from the reaction system. A 2D morphological map was established as a function of crosslinker concentration and the polar monomer AA concentration, in comonomer feed in the transition between the morphology domains. The effect of the covalent crosslinker DVB on the morphology of the polymer network was investigated in detail at AA fraction of 40 vol%. The ratios of acid to ethylene oxide units presenting in the comonomers dramatically affected the polymer-polymer interaction and hence the morphology of the resultant polymer network. The covalent crosslinking by DVB and the hydrogen bonding crosslinking between two acid units as well as between the acid and ethylene oxide unit played key roles in the formation of monodisperse polymer microspheres.展开更多
Titania-grafted poly（styrene-divinylbenzene）（TiO2/PSt-DVB） nanocomposite microspheres were prepared by an open-ring reaction and radical grafting copolymerization method. The TiO2 nanoparticles were first modified...Titania-grafted poly（styrene-divinylbenzene）（TiO2/PSt-DVB） nanocomposite microspheres were prepared by an open-ring reaction and radical grafting copolymerization method. The TiO2 nanoparticles were first modified by attachment of epoxy groups to their surfaces to provide reactive groups that could covalently bond to the polymer （PSt-DVB） microspheres. The nanocomposite obtained was characterized by FTIR, SEM, XRD, and TGA analyses as well as UV-Vis spectrophotometry. The results indicated that the TiO2 nanoparticles were uniformly grafted onto the surface of the polymer microsphere producing grain sizes of about 5―10 μm. The modified TiO2 showed better UV absorbing property than the unmodified form, and the nanocomposite also retained the same UV absorbing property as the free modified TiO2 nanoparticle.展开更多
Porous hybrid microspheres were fabricated by the synthesized calcium gluconate-g-poly（D,L-lactide） （CG-g- PDLLA） composites. These hybrid microspheres were treated with an alkaline solution for different period o...Porous hybrid microspheres were fabricated by the synthesized calcium gluconate-g-poly（D,L-lactide） （CG-g- PDLLA） composites. These hybrid microspheres were treated with an alkaline solution for different period of time to control the amount of generated carboxylate groups and remained CG on the surface. The microspheres were then incubated in a supersaturated simulated body fluid （1.5 SBF） solution for different time to investigate their biomimetic mineralization behavior. The depositions were found to have a fine cluster morphology, a similar crystal structure and chemical structure to natural hydroxyapatite, and a medium Ca/P of approximately 1.30. The effect of surface treating time on the structure and mineralization behavior of these microspheres has been discussed in detail. The results indicate that the nucleation and growth of apatite on the surface are influenced by the induced carboxylate groups and the remained CG. The hybrid CG-g- PDLLA microspheres have the potential as a novel alternative in bone tissue engineering.展开更多
Microparticles with diameter within the range of Dn = 26-38 μm were prepared from functional poly（ester- anhydride）s with different amount of allyl groups in the side chains, using emulsion solvent evaporation tech...Microparticles with diameter within the range of Dn = 26-38 μm were prepared from functional poly（ester- anhydride）s with different amount of allyl groups in the side chains, using emulsion solvent evaporation technique. Porous structure was obtained as the effect of photocrosslinking of aUyl groups. 2,2-Dimetoxy-2-phenylacetophenone （DMPA） （0.5 wt%-10 wt%） was used as a photoinitiator. The crosslinking was carried out by UV irradiation during the solvent evaporation. Effectiveness of the crosslinking was characterized by the content of insoluble part of samples and it was in the range of 18%-75%. Porosity of microparticles （in the range of 76%-88%） depended on the functionality of poly（ester- anhydride）s and amount of the photoinitiator used. The most porous particles were obtained with use of 0.5 wt% of DMPA. Their flow ability expressed by Carr＇s index was excellent, and their theoretical mass mean aerodynamic diameters were acceptable for use in pulmonary drug delivery. The most porous particles were loaded with p-nitroaniline, theophilline or doxycycline. The loading efficiencies of drugs in porous microspheres were higher compared to nonporous ones. The porosity of loaded microparticles was slightly decreased, however their flow ability was still very good.展开更多
基金This work was supported in part by the National Science Foundation of China (No. 20504015)the starting project for young teachers from the Ministry of Education, China.
文摘Monodisperse poly（poly（ethyleneglycol） methyl ether acrylate-co-acrylic acid） （poly（PEGMA-co-AA）） microspheres were prepared by distillation-precipitation polymerization with divinylbenzene （DVB） as crosslinker with 2,2＇- azobisisobutyronitrile （AIBN） as initiator in neat acetonitrile without stirring. Under various reaction conditions, four distinct morphologies including the sol, microemulsion, microgels and microspheres were formed during the distillation of the solvent from the reaction system. A 2D morphological map was established as a function of crosslinker concentration and the polar monomer AA concentration, in comonomer feed in the transition between the morphology domains. The effect of the covalent crosslinker DVB on the morphology of the polymer network was investigated in detail at AA fraction of 40 vol%. The ratios of acid to ethylene oxide units presenting in the comonomers dramatically affected the polymer-polymer interaction and hence the morphology of the resultant polymer network. The covalent crosslinking by DVB and the hydrogen bonding crosslinking between two acid units as well as between the acid and ethylene oxide unit played key roles in the formation of monodisperse polymer microspheres.
基金Fosan Scientific Special Funds of Production-Study-Research(No.2006A034)
文摘Titania-grafted poly（styrene-divinylbenzene）（TiO2/PSt-DVB） nanocomposite microspheres were prepared by an open-ring reaction and radical grafting copolymerization method. The TiO2 nanoparticles were first modified by attachment of epoxy groups to their surfaces to provide reactive groups that could covalently bond to the polymer （PSt-DVB） microspheres. The nanocomposite obtained was characterized by FTIR, SEM, XRD, and TGA analyses as well as UV-Vis spectrophotometry. The results indicated that the TiO2 nanoparticles were uniformly grafted onto the surface of the polymer microsphere producing grain sizes of about 5―10 μm. The modified TiO2 showed better UV absorbing property than the unmodified form, and the nanocomposite also retained the same UV absorbing property as the free modified TiO2 nanoparticle.
基金supported by the National Natural Science Foundation of China(Nos.51025314 and 21104089)the Fundamental Research Funds for the Central Universities(No.ZY1632)
文摘Porous hybrid microspheres were fabricated by the synthesized calcium gluconate-g-poly（D,L-lactide） （CG-g- PDLLA） composites. These hybrid microspheres were treated with an alkaline solution for different period of time to control the amount of generated carboxylate groups and remained CG on the surface. The microspheres were then incubated in a supersaturated simulated body fluid （1.5 SBF） solution for different time to investigate their biomimetic mineralization behavior. The depositions were found to have a fine cluster morphology, a similar crystal structure and chemical structure to natural hydroxyapatite, and a medium Ca/P of approximately 1.30. The effect of surface treating time on the structure and mineralization behavior of these microspheres has been discussed in detail. The results indicate that the nucleation and growth of apatite on the surface are influenced by the induced carboxylate groups and the remained CG. The hybrid CG-g- PDLLA microspheres have the potential as a novel alternative in bone tissue engineering.
文摘Microparticles with diameter within the range of Dn = 26-38 μm were prepared from functional poly（ester- anhydride）s with different amount of allyl groups in the side chains, using emulsion solvent evaporation technique. Porous structure was obtained as the effect of photocrosslinking of aUyl groups. 2,2-Dimetoxy-2-phenylacetophenone （DMPA） （0.5 wt%-10 wt%） was used as a photoinitiator. The crosslinking was carried out by UV irradiation during the solvent evaporation. Effectiveness of the crosslinking was characterized by the content of insoluble part of samples and it was in the range of 18%-75%. Porosity of microparticles （in the range of 76%-88%） depended on the functionality of poly（ester- anhydride）s and amount of the photoinitiator used. The most porous particles were obtained with use of 0.5 wt% of DMPA. Their flow ability expressed by Carr＇s index was excellent, and their theoretical mass mean aerodynamic diameters were acceptable for use in pulmonary drug delivery. The most porous particles were loaded with p-nitroaniline, theophilline or doxycycline. The loading efficiencies of drugs in porous microspheres were higher compared to nonporous ones. The porosity of loaded microparticles was slightly decreased, however their flow ability was still very good.
