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Diblock Copolymer Micelles (diblock + copolymer_micelle)
Selected AbstractsA Novel Biodegradable and Light-Breakable Diblock Copolymer Micelle for Drug Delivery,ADVANCED ENGINEERING MATERIALS, Issue 3 2009Zhigang Xie A facile approach to the preparation of light-responsive copolymer micelles is developed. This approach is based on the attachment of hydrophobic groups to one block of a diblock copolymer via a light-sensitive linkage. The micelles can be dissociated under light irradiation and release the encapsulated pyrene. The obtained polymeric micelles are expected to be of use as drug-delivery vehicles. [source] Highly Ordered Hexagonal Arrays of Hybridized Micelles from Bimodal Self-Assemblies of Diblock Copolymer MicellesMACROMOLECULAR RAPID COMMUNICATIONS, Issue 7 2010Seong Il Yoo Abstract We demonstrate the formation of highly ordered hexagonal arrays of hybridized polystyrene,poly(4-vinyl pyridine), PS,PVP, micelles with controllable size by solvent annealing techniques. Because the formation of hybridized micelles was prohibited in the mixture solutions of two different-sized PS,PVP micelles, single-layered films with bimodal self-assemblies of small and large micelles were fabricated from the mixture solutions by adjusting their mixing ratios. When the single-layered films were solvent annealed by saturated vapor of tetrahydrofuran (THF), on the other hand, small and large PS,PVP micelles in the bimodal self-assemblies merged together to form hybridized micelles. In addition, the hybridized micelles arranged themselves in a highly ordered hexagonal array, the diameter and center-to-center distance of which were precisely adjusted by varying the mixing ratio of small to large micelles in the bimodal assemblies. [source] Tunable Memory Characteristics of Nanostructured, Nonvolatile Charge Trap Memory Devices Based on a Binary Mixture of Metal Nanoparticles as a Charge Trapping Layer,ADVANCED MATERIALS, Issue 2 2009Jang-Sik Lee Tunable memory characteristics are investigated according to the metal-nanoparticle species being used in memory devices. The memory devices are fabricated using diblock copolymer micelles as templates to synthesize nanoparticles of cobalt, gold, and a binary mixture thereof. Programmable memory characteristics show different charging/discharging behaviors according to the storage element configurations as confirmed by nanoscale device characterization. [source] Solubilization of hydrophobic drugs by methoxy poly(ethylene glycol)-block-polycaprolactone diblock copolymer micelles: Theoretical and experimental data and correlationsJOURNAL OF PHARMACEUTICAL SCIENCES, Issue 3 2008Kevin Letchford Abstract The solubilization of five model hydrophobic drugs by a series of micelle-forming, water-soluble methoxy poly(ethylene glycol)-block-polycaprolactone diblock copolymers (MePEG-b-PCL) with varying methoxy poly(ethylene glycol) (MePEG) and polycaprolactone (PCL) block lengths was investigated. Variation of the feed weight ratio of MePEG to caprolactone resulted in the synthesis of copolymers with predictable block lengths. The micelle diameter and pyrene partition coefficient (Kv) were directly related to the PCL block length whereas the critical micelle concentrations (CMC) were inversely related to the PCL block length. The aqueous solubilities of the model hydrophobic drugs, indomethacin, curcumin, plumbagin, paclitaxel, and etoposide were increased by encapsulation within the micelles. Drug solubilization was directly related to the compatibility between the solubilizate and PCL as determined by the Flory,Huggins interaction parameter (,sp). Furthermore, the concentration of solubilized drug was also directly related to the PCL block length. © 2007 Wiley-Liss, Inc. and the American Pharmacists Association J Pharm Sci 97:1179,1190, 2008 [source] Micellar Structures of Hydrophilic/Lipophilic and Hydrophilic/Fluorophilic Poly(2-oxazoline) Diblock Copolymers in WaterMACROMOLECULAR CHEMISTRY AND PHYSICS, Issue 21 2008Ruzha Ivanova Abstract Amphiphilic poly(2-alkyl-2-oxazoline) diblock copolymers of 2-methyl-2-oxazoline (MOx) building the hydrophilic block and either 2-nonyl-2-oxazoline (NOx) for the hydrophobic or 2-(1H,1H,,2H,2H,-perfluorohexyl)-2-oxazoline (FOx) for the fluorophilic block were synthesized by sequential living cationic polymerization. The polymer amphiphiles form core/shell micelles in aqueous solution as evidenced using small-angle neutron scattering (SANS). Whereas the diblock copolymer micelles with a hydrophobic NOxn block are spherical, the micelles with the fluorophilic FOxn are slightly elongated, as observed by SANS and TEM. In water, the micelles with fluorophilic and lipophilic cores do not mix, but coexist. [source] Characterization of single-walled carbon nanotubes synthesized using iron and cobalt nanoparticles derived from self-assembled diblock copolymer micellesAPPLIED ORGANOMETALLIC CHEMISTRY, Issue 8 2010Qiang Fu Abstract We present a comparative study of single-walled carbon nanotubes grown using iron and cobalt nanoparticles as catalysts via the chemical vapor deposition approach. Monodispersed iron and cobalt oxide nanoparticles with an average size of 2 nm were prepared using a polystyrene- b -poly (4-vinylpyridine) diblock copolymermicelle template. The 2 nm iron oxide nanoparticles generated single-walled carbon nanotubes with an average diameter of 1.5 nm while 2 nm cobalt oxide nanoparticles produced single-walled carbon nanotubes with an average diameter of 1.0 nm. To achieve high growth yield using iron nanoparticles as catalyst, higher carbon feed rate is required. These findings demonstrate the importance of the synergic interaction between catalyst and carbon precursor in single-walled carbon nanotube formation. It also elucidates the important role of catalyst chemical composition on carbon nanotube properties. Copyright © 2010 John Wiley & Sons, Ltd. [source] | ||||||||||||||||||||||