The Experts below are selected from a list of 291 Experts worldwide ranked by ideXlab platform

Yoji Shibutani - One of the best experts on this subject based on the ideXlab platform.

  • The Energetics of Large Deformations of a Single Polyimide Molecular Chain: DFT and MO Calculations
    Macromolecular Theory and Simulations, 2008
    Co-Authors: Akinori Fujinami, Shigenobu Ogata, Hajime Kimizuka, Yoji Shibutani
    Abstract:

    The large-deformation energetics of a single Molecular Chain of the rod-like polyimide PMDA-PDA was investigated using DFT, ab initio MO and semi-empirical MO methods. The force/ displacement curves were calculated from tensile testing simulations along the axis of the Molecular Chain, allowing a discussion of the distribution and change of local strain of the Molecular Chain. The deformation behavior of a single PMDA-PDA Molecular Chain under finite deformations as functions of bending angle and dihedral angle between PMDA and PDA groups are compared. It is found that the semi-empirical MO calculations provide sufficient accuracy to express the energetics of large deformations except for compressive deformation.

  • Ab initio study of the tensile behavior of single polyimide Molecular Chain
    Polymer, 2004
    Co-Authors: Akinori Fujinami, Shigenobu Ogata, Yoji Shibutani
    Abstract:

    This study investigates the tensile (compressive) behavior of a single Molecular Chain of the rod-like polyimide poly-(p-phenylene pyromellitimide) (PMDA-PDA) at zero temperature using a density functional theory (DFT) calculation. The force–displacement curve of the single PMDA-PDA Molecular Chain is calculated from simulations of predefined strain deformations along the axis of the Molecular Chain, allowing a discussion of the distribution and change of local strain of the Molecular Chain. We find that the six-membered ring of the PDA group deforms the most until an engineering strain of 7.0% under uniaxial tensile develops. However, eventually carbon–nitrogen bonds between the PMDA and PDA groups break at the point where fracture of the Molecular Chain occurs. q 2004 Elsevier Ltd. All rights reserved.

Carole Sentein - One of the best experts on this subject based on the ideXlab platform.

  • influence of polar Molecular Chain orientation on optical and carrier transport properties of polymer blends
    Organic Electronics, 2007
    Co-Authors: V Kažukauskas, V. Cyras, M Pranaitis, Aleksandra Apostoluk, Licinio Rocha, L Sicot, Paul Raimond, Carole Sentein
    Abstract:

    Abstract We report investigation of optical and electrical properties of poly(9-vinylcarbazole) (PVK) doped with 30 wt% 4-dibutylamino-4′-nitrostilbene (DBANS), depending on the Molecular Chain orientation of polar DBANS molecules. Orientation of dopant diode-like DBANS dye molecules was achieved by application of a static electric field through the polymer film, while heating the material near its glass transition temperature ( T g ). Modification of optical properties due to the orientation was evidenced by the spectral dependencies of absorption coefficient. Appearance of the orientation-induced built-in electrical field was proven optically by the solid electric field induced second harmonic generation (SEFISHG) and electrically by current–voltage ( IV ) characterization. Measurement of the thermally stimulated currents (TSC) spectra demonstrated that carrier transport and trapping are affected, too. Changes of the TSCs induced by orientation were expressed best in the temperature range of 280–290 K. They could be attributed to the thermally activated process with activation energy of about 0.38 eV.

  • Influence of polar Molecular Chain orientation on optical and carrier transport properties of polymer blends
    Organic Electronics, 2007
    Co-Authors: V Kažukauskas, M Pranaitis, Aleksandra Apostoluk, Licinio Rocha, L Sicot, Paul Raimond, V. Čyras, Carole Sentein
    Abstract:

    We report investigation of optical and electrical properties of poly(9-vinylcarbazole) (PVK) doped with 30 wt% 4-dibutylamino-4′-nitrostilbene (DBANS), depending on the Molecular Chain orientation of polar DBANS molecules. Orientation of dopant diode-like DBANS dye molecules was achieved by application of a static electric field through the polymer film, while heating the material near its glass transition temperature (Tg). Modification of optical properties due to the orientation was evidenced by the spectral dependencies of absorption coefficient. Appearance of the orientation-induced built-in electrical field was proven optically by the solid electric field induced second harmonic generation (SEFISHG) and electrically by current–voltage (IV) characterization. Measurement of the thermally stimulated currents (TSC) spectra demonstrated that carrier transport and trapping are affected, too. Changes of the TSCs induced by orientation were expressed best in the temperature range of 280–290 K. They could be attributed to the thermally activated process with activation energy of about 0.38 eV. Previous article in issue

Eric Lichtfouse - One of the best experts on this subject based on the ideXlab platform.

  • effects of Molecular Chain length on the contact line movement in water n alkane solid systems
    Polymers, 2019
    Co-Authors: Wenxiu Zheng, Chengzhen Sun, Boyao Wen, Bofeng Bai, Eric Lichtfouse
    Abstract:

    The movement of the contact line in liquid-liquid-solid systems is a major phenomenon in natural and industrial processes. In particular, n-alkanes are widely occurring in the oil, soil pollution, and chemical industries, yet there is little knowledge on the effects of Molecular Chain length on the contact line movement. Here, we studied the effects of Molecular Chain length on the contact line movement in water/n-alkane/solid systems with different surface wettabilities. We used n-heptane (C7), n-decane (C10), and n-hexadecane (C16) as alkanes and α-quartz as the solid surface. We calculated the time-variation contact line moving velocity and also analyzed the jump frequency and the mean distance of the Molecular displacement occurring within the contact line zone by Molecular-kinetic theory. Molecular dynamics simulation results show that the contact line velocity decreases with increasing the Chain length, originally caused by the decreasing the jump frequency and mean distance. These variations with the Molecular Chain length are related to the more torsions and deformations of the molecules with a longer Chain length. In addition, the moving mechanism of the contact line on the same solid surface does not change at different Molecular Chain lengths, implying that the moving mechanism mainly depends on the three-phase wettability.

  • Effects of Molecular Chain Length on the Contact Line Movement in Water/n-Alkane/Solid Systems.
    Polymers, 2019
    Co-Authors: Wenxiu Zheng, Chengzhen Sun, Boyao Wen, Bofeng Bai, Eric Lichtfouse
    Abstract:

    The movement of the contact line in liquid-liquid-solid systems is a major phenomenon in natural and industrial processes. In particular, n-alkanes are widely occurring in the oil, soil pollution, and chemical industries, yet there is little knowledge on the effects of Molecular Chain length on the contact line movement. Here, we studied the effects of Molecular Chain length on the contact line movement in water/n-alkane/solid systems with different surface wettabilities. We used n-heptane (C7), n-decane (C10), and n-hexadecane (C16) as alkanes and α-quartz as the solid surface. We calculated the time-variation contact line moving velocity and also analyzed the jump frequency and the mean distance of the Molecular displacement occurring within the contact line zone by Molecular-kinetic theory. Molecular dynamics simulation results show that the contact line velocity decreases with increasing the Chain length, originally caused by the decreasing the jump frequency and mean distance. These variations with the Molecular Chain length are related to the more torsions and deformations of the molecules with a longer Chain length. In addition, the moving mechanism of the contact line on the same solid surface does not change at different Molecular Chain lengths, implying that the moving mechanism mainly depends on the three-phase wettability.

Akinori Fujinami - One of the best experts on this subject based on the ideXlab platform.

  • The Energetics of Large Deformations of a Single Polyimide Molecular Chain: DFT and MO Calculations
    Macromolecular Theory and Simulations, 2008
    Co-Authors: Akinori Fujinami, Shigenobu Ogata, Hajime Kimizuka, Yoji Shibutani
    Abstract:

    The large-deformation energetics of a single Molecular Chain of the rod-like polyimide PMDA-PDA was investigated using DFT, ab initio MO and semi-empirical MO methods. The force/ displacement curves were calculated from tensile testing simulations along the axis of the Molecular Chain, allowing a discussion of the distribution and change of local strain of the Molecular Chain. The deformation behavior of a single PMDA-PDA Molecular Chain under finite deformations as functions of bending angle and dihedral angle between PMDA and PDA groups are compared. It is found that the semi-empirical MO calculations provide sufficient accuracy to express the energetics of large deformations except for compressive deformation.

  • Ab initio study of the tensile behavior of single polyimide Molecular Chain
    Polymer, 2004
    Co-Authors: Akinori Fujinami, Shigenobu Ogata, Yoji Shibutani
    Abstract:

    This study investigates the tensile (compressive) behavior of a single Molecular Chain of the rod-like polyimide poly-(p-phenylene pyromellitimide) (PMDA-PDA) at zero temperature using a density functional theory (DFT) calculation. The force–displacement curve of the single PMDA-PDA Molecular Chain is calculated from simulations of predefined strain deformations along the axis of the Molecular Chain, allowing a discussion of the distribution and change of local strain of the Molecular Chain. We find that the six-membered ring of the PDA group deforms the most until an engineering strain of 7.0% under uniaxial tensile develops. However, eventually carbon–nitrogen bonds between the PMDA and PDA groups break at the point where fracture of the Molecular Chain occurs. q 2004 Elsevier Ltd. All rights reserved.

Tomio Petrosky - One of the best experts on this subject based on the ideXlab platform.

  • anomalous diffusion of a quantum brownian particle in a one dimensional Molecular Chain
    Physical Review E, 2020
    Co-Authors: Sho Nakade, Kazuki Kanki, Satoshi Tanaka, Tomio Petrosky
    Abstract:

    We discuss anomalous relaxation processes of a quantum Brownian particle which interacts with an acoustic phonon field as a thermal reservoir in one-dimensional Chain molecule. We derive a kinetic equation for the particle using the complex spectral representation of the Liouville-von Neumann operator. Due to the one-dimensionality, the momentum space separates into infinite sets of disjoint irreducible subspaces dynamically independent of one another. Hence, momentum relaxation occurs only within each subspace toward the Maxwell distribution. We obtain a hydrodynamic mode with transport coefficients, a sound velocity, and a diffusion coefficient, defined in each subspace. Moreover, because the sound velocity has momentum dependence, phase mixing affects the broadening of the spatial distribution of the particle in addition to the diffusion process. Due to the phase mixing, the increase rate of the mean-square displacement of the particle increases linearly with time and diverges in the long-time limit.

  • Nonequilibrium transport on a quantum Molecular Chain in terms of the complex Liouvillian spectrum.
    Physical Review E, 2011
    Co-Authors: Satoshi Tanaka, Kazuki Kanki, Tomio Petrosky
    Abstract:

    The transport process in a Molecular Chain in a nonequilibrium stationary state is theoretically investigated. The molecule is interacting at both ends with thermal baths of different temperatures, while no dissipation mechanism is contained inside the Molecular Chain. We have first obtained the nonequilibrium stationary state outside the Hilbert space in terms of the complex spectral representation of Liouvillian. The nonequilibrium stationary state is obtained as an eigenstate of the Liouvillian, which is constructed through the collision invariant of the kinetic equation. The eigenstate of the Liouvillian contains information on the spatial correlation between the Molecular Chain and the thermal baths. While energy flow in the nonequilibrium state which is due to the first-order correlation can be described by the Landauer formula, the particle current due to the second-order correlation cannot be described by the Landauer formula. The present method provides a simple way to evaluate the energy transport in a Molecular Chain in a nonequilibrium situation.