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V P Shibaev - One of the best experts on this subject based on the ideXlab platform.
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Synthesis Phase behaviour and photo optical properties of bent core methacrylate with azobenzene group and corresponding side chain polymethacrylate
RSC Advances, 2016Co-Authors: Vladimira Novotna, V P Shibaev, Alexey Bobrovsky, Damian Pociecha, Miroslav Kaspar, Věra HamplovaAbstract:In the present work, Synthesis of a new photosensitive bent-core monomer and corresponding side-chain polymethacrylate is described. The liquid crystalline (LC) properties were studied by texture observation, calorimetric and electro-optical measurements. Structural parameters of the LC Phases were established from X-ray diffraction. Due to presence of the azobenzene group both compounds revealed photosensitivity and UV-irradiation effectively induces the E–Z isomerization process. The photo-optical properties of the spin-coated films of polymethacrylate are analysed and it is found that irradiation with polarized light aligns chromophores in the direction perpendicular to the polarization plane of incident light. Photoorientation proceeds more effectively in the amorphousized films in comparison with annealed LC films.
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new chiral photochromic menthone containing homopolymers and copolymers Synthesis Phase behaviour and photo optical properties
Liquid Crystals, 1999Co-Authors: Yu A Bobrovsky, N I Boiko, V P ShibaevAbstract:A new approach for the preparation of photosensitive materials for coloured data recording and storage is advanced. This approach involves the Synthesis of copolymers containing nematogenic and combined (-)-arylidene-p-menthan-3-one chiral photochromic fragments in one monomer unit. The conditions for the formation of an LC Phase in the chiral photochromic homopolymers as a function of the structure of the side groups have been identified; for a new series of copolymers, the effect of their composition on the Phase behaviour and photooptical properties is considered. Planarly oriented films of the copolymers show selective light reflection in the UV, visible, and near IR spectral regions. The photochemical behaviour of the homopolymers and copolymers in dilute solution and as films has been studied. In these systems, under UV radiation, the E-Z isomerization of the (-)-arylidene-p-menthan-3-one fragment is the dominating process. The kinetic features of the photoprocess are revealed, and the effective qua...
Kwang Ho Kim - One of the best experts on this subject based on the ideXlab platform.
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Synthesis Phase composition modification and optical properties of ce3 tb3 activated kgdf4 and gdf3 submicrocrystals
Journal of Solid State Chemistry, 2012Co-Authors: Chunyan Cao, Hyun Kyoung Yang, Byung Kee Moon, Byung Chun Choi, Jung Hyun Jeong, Kwang Ho KimAbstract:Abstract Ce 3+ /Tb 3+ co-doped series of samples have been synthesized based on a citric acid assisted hydrothermal method. By controlling the hydrothermal treating time, the samples evolve from the Ce 3+ /Tb 3+ co-doped cubic Phase KGdF 4 with spherical morphology into the Ce 3+ /Tb 3+ co-doped orthorhombic Phase GdF 3 with rhombic shape finally. The X-ray diffraction data illustrate the Phase composition modification process of the samples. The field emission scanning electron microscopy and the transmission electron microscopy images suggest the transformation in the morphology of final products. The spectra of the energy-dispersive spectroscopy reveal the constituents of the samples. And the selected area electronic diffraction patterns prove the crystalline Phases of the samples. Based on previous studies and the experimental data, one possible Phase composition modification process has been summarized. The photoluminescence excitation and emission spectra and the luminescent dynamic decay curves demonstrate the variations in optical properties of the Ce 3+ /Tb 3+ co-doped final products.
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ce3 tb3 activated gdf3 kgdf4 and cef3 submicro nanocrystals Synthesis Phase evolution and optical properties
Journal of Materials Research, 2011Co-Authors: Chunyan Cao, Hyun Kyoung Yang, Byung Kee Moon, Byung Chun Choi, Jung Hyun Jeong, Jong Won Chung, Kwang Ho KimAbstract:Based on a citric acid-assisted hydrothermal method, series of Ce 3+ /Tb 3+ activated fluorides have been synthesized. By controlling the amount of KNO 3 , the final products evolve from the Ce 3+ /Tb 3+ codoped orthorhombic Phase GdF 3 to the Ce 3+ /Tb 3+ codoped cubic Phase KGdF 4 . The concentration of Ce 3+ has great effects on the crystalline Phases and the morphologies of final products. The Ce 3+ concentration dependent samples illustrate the appearance of the hexagonal Phase solid solution CeF 3 –GdF 3 –TbF 3 in the final products. When the Ce 3+ concentration is 20 mol%, the sample Ce20 presents the hexagonal Phase CeF 3 but the diffraction peaks move to higher degree. The x-ray diffraction patterns suggest the Phase evolution of final products, the field emission scanning electron microscopy images present the variation in morphology of samples, and the photoluminescence excitation and emission spectra as well as the luminescent dynamic curves illustrate the optical properties of samples.
Chunyan Cao - One of the best experts on this subject based on the ideXlab platform.
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Synthesis Phase composition modification and optical properties of ce3 tb3 activated kgdf4 and gdf3 submicrocrystals
Journal of Solid State Chemistry, 2012Co-Authors: Chunyan Cao, Hyun Kyoung Yang, Byung Kee Moon, Byung Chun Choi, Jung Hyun Jeong, Kwang Ho KimAbstract:Abstract Ce 3+ /Tb 3+ co-doped series of samples have been synthesized based on a citric acid assisted hydrothermal method. By controlling the hydrothermal treating time, the samples evolve from the Ce 3+ /Tb 3+ co-doped cubic Phase KGdF 4 with spherical morphology into the Ce 3+ /Tb 3+ co-doped orthorhombic Phase GdF 3 with rhombic shape finally. The X-ray diffraction data illustrate the Phase composition modification process of the samples. The field emission scanning electron microscopy and the transmission electron microscopy images suggest the transformation in the morphology of final products. The spectra of the energy-dispersive spectroscopy reveal the constituents of the samples. And the selected area electronic diffraction patterns prove the crystalline Phases of the samples. Based on previous studies and the experimental data, one possible Phase composition modification process has been summarized. The photoluminescence excitation and emission spectra and the luminescent dynamic decay curves demonstrate the variations in optical properties of the Ce 3+ /Tb 3+ co-doped final products.
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ce3 tb3 activated gdf3 kgdf4 and cef3 submicro nanocrystals Synthesis Phase evolution and optical properties
Journal of Materials Research, 2011Co-Authors: Chunyan Cao, Hyun Kyoung Yang, Byung Kee Moon, Byung Chun Choi, Jung Hyun Jeong, Jong Won Chung, Kwang Ho KimAbstract:Based on a citric acid-assisted hydrothermal method, series of Ce 3+ /Tb 3+ activated fluorides have been synthesized. By controlling the amount of KNO 3 , the final products evolve from the Ce 3+ /Tb 3+ codoped orthorhombic Phase GdF 3 to the Ce 3+ /Tb 3+ codoped cubic Phase KGdF 4 . The concentration of Ce 3+ has great effects on the crystalline Phases and the morphologies of final products. The Ce 3+ concentration dependent samples illustrate the appearance of the hexagonal Phase solid solution CeF 3 –GdF 3 –TbF 3 in the final products. When the Ce 3+ concentration is 20 mol%, the sample Ce20 presents the hexagonal Phase CeF 3 but the diffraction peaks move to higher degree. The x-ray diffraction patterns suggest the Phase evolution of final products, the field emission scanning electron microscopy images present the variation in morphology of samples, and the photoluminescence excitation and emission spectra as well as the luminescent dynamic curves illustrate the optical properties of samples.
Věra Hamplova - One of the best experts on this subject based on the ideXlab platform.
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Synthesis Phase behaviour and photo optical properties of bent core methacrylate with azobenzene group and corresponding side chain polymethacrylate
RSC Advances, 2016Co-Authors: Vladimira Novotna, V P Shibaev, Alexey Bobrovsky, Damian Pociecha, Miroslav Kaspar, Věra HamplovaAbstract:In the present work, Synthesis of a new photosensitive bent-core monomer and corresponding side-chain polymethacrylate is described. The liquid crystalline (LC) properties were studied by texture observation, calorimetric and electro-optical measurements. Structural parameters of the LC Phases were established from X-ray diffraction. Due to presence of the azobenzene group both compounds revealed photosensitivity and UV-irradiation effectively induces the E–Z isomerization process. The photo-optical properties of the spin-coated films of polymethacrylate are analysed and it is found that irradiation with polarized light aligns chromophores in the direction perpendicular to the polarization plane of incident light. Photoorientation proceeds more effectively in the amorphousized films in comparison with annealed LC films.
Yashayahu Talmon - One of the best experts on this subject based on the ideXlab platform.
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aggregation properties and mixing behavior of hydrocarbon fluorocarbon and hybrid hydrocarbon fluorocarbon cationic dimeric surfactants
Langmuir, 2000Co-Authors: Reiko Oda, Ivan Huc, And Dganit Danino, Yashayahu TalmonAbstract:The Synthesis, Phase behavior, and mixing properties of cationic dimeric (gemini) surfactants having one or two perfluoroalkyl chains is described and compared to that of analogue hydrocarbon surfactants. The combination of the dimeric character of the amphiphiles with the high hydrophobicity of the fluorocarbon chains leads to very low critical micelle concentration values and unusually low characteristic times of exchange between surfactants in the bulk solution and surfactants in the aggregate. This results in slow exchange on the NMR time scale, which allows a practical study of micellization and comicellization by NMR. With respect to the morphology of the aggregates, the fluorocarbon amphiphiles do not simply behave as more hydrophobic amphiphiles. Instead, they assemble into various structures including very stable unilamellar and multilamellar vesicles not seen in their hydrocarbon analogues. The hybrid hydrocarbon−fluorocarbon dimeric surfactant exhibits features of both families. In particular i...
