The Experts below are selected from a list of 363 Experts worldwide ranked by ideXlab platform

Mitsuru Akashi - One of the best experts on this subject based on the ideXlab platform.

  • Stepwise Assembly of Isotactic Poly(Methyl Methacrylate) and Syndiotactic Poly(Methacrylic Acid) on a Substrate
    Langmuir, 2000
    Co-Authors: Takeshi Serizawa, Ken-ichi Hamada, Tatsuki Kitayama, Ken-ichi Katsukawa, And Koichi Hatada, Mitsuru Akashi
    Abstract:

    Stepwise assembly of isotactic poly(methyl methacrylate) and syndiotactic poly(methacrylic acid) from acetonitrile and mixed acetonitrile/water solutions, respectively, onto a gold substrate was studied. Quantitative quartz crystal microbalance analysis of the molar ratio (monomer unit) between assembled polymers suggested stepwise stereocomplex formation. The assembled amount and the assembly ratio between PMAA and PMAA were dependent on the acetonitrile content of the poly(methacrylic acid) solution. Infrared spectra of the assembly and cast films of each polymer also showed stereocomplex formation in the assembly. Atomic force microscopic observation showed the assembled polymer to have a Molecularly Smooth Surface. The solvent species used was an important factor in stereocomplex formation at the liquid−polymer film interface.

N. V. Churaev - One of the best experts on this subject based on the ideXlab platform.

  • Kinetics and Isotherms of Cationic Polyelectrolyte Adsorption on Quartz
    Colloid Journal, 2003
    Co-Authors: I. P. Sergeeva, V. D. Sobolev, T. B. Ermakova, N. V. Churaev
    Abstract:

    The kinetics of the formation of quartz Surface charge in the solutions of a cationic polyelectrolyte, poly(styrene- co -dimethyl aminopropylmaleimide) with the molecular mass M = 20  000 is studied in the concentration range from 10^–5 to 0.5 g/l in 10^–4 M KCl background solution at pH 6.5. Quartz capillaries with the radius from 5 to 10 μm and Molecularly Smooth Surface are used as model systems. Characteristic times of the formation of the Surface charge at equilibrium with the solution are calculated from the data on the kinetics of adsorption; these times are equal to 40–50 min for the region of electrostatic adsorption (before the Surface charge reversal) and 20–25 min, for the region of hydrophobic adsorption upon the formation of the second adlayer. Based on the steady values of the Surface charge, the isotherms and potentials of adsorption of cationic polyelectrolyte are calculated. Electrostatic adsorption isotherm is described by the Langmuir equation with the energy of molecular adsorption of 25.4 kT . It is shown that, at polymer concentration above 10^–2 g/l, the conformation of adsorbed molecules ceases to be planar. However, even in this case, we succeed in calculating the Surface charge using the Helmholtz and Gouy equations and applying the pressure drops at the capillary ends higher than 10 atm, when under the loading of increasing shear stress in the Surface layer the conformation of adsorbed molecules approaches the planar shape. Based on the two-layer model of the formation of Surface charge developed earlier, it is shown that the energy of hydrophobic adsorption is smaller than that of electrostatic adsorption and is equal to 17.7 kT . Possible physical mechanisms of electrostatic and hydrophobic adsorption of cationic polyelectrolyte molecules on quartz are discussed.

  • Adsorption layers of poly(ethylene oxide) on quartz studied using capillary electrokinetics
    Colloids and Surfaces A: Physicochemical and Engineering Aspects, 1993
    Co-Authors: N. V. Churaev, I. P. Sergeeva, V. D. Sobolev, Z. M. Zorin, E. K. Gasanov
    Abstract:

    Abstract The adsorption of poly(ethylene oxide) (PEO) molecules decreases the electrokinetic potential of a quartz Surface. The corresponding change in electrostatic forces may influence the interaction between colloidal particles in polymer solutions. The equilibrium between flowing PEO solution and adsorption layers in thin quartz capillaries is established after 1–2 h. The kinetics may be controlled by the attachment and reconformation of polymer molecules in the adsorbed layers. The saturated adsorption layers of PEO are easily deformed under the action of the shear stress of the flowing solution. The effect of shear stress requires further investigation using joint measurements of the adsorption and the hydrodynamic and electrokinetic thicknesses of the adsorption layers. The thin quartz capillaries represent a simple model system with a well-characterized geometry and a Molecularly Smooth Surface. Capillary electrokinetics may effectively be used for the investigation of electroSurface phenomena in polymer solutions.

E. K. Gasanov - One of the best experts on this subject based on the ideXlab platform.

  • Adsorption layers of poly(ethylene oxide) on quartz studied using capillary electrokinetics
    Colloids and Surfaces A: Physicochemical and Engineering Aspects, 1993
    Co-Authors: N. V. Churaev, I. P. Sergeeva, V. D. Sobolev, Z. M. Zorin, E. K. Gasanov
    Abstract:

    Abstract The adsorption of poly(ethylene oxide) (PEO) molecules decreases the electrokinetic potential of a quartz Surface. The corresponding change in electrostatic forces may influence the interaction between colloidal particles in polymer solutions. The equilibrium between flowing PEO solution and adsorption layers in thin quartz capillaries is established after 1–2 h. The kinetics may be controlled by the attachment and reconformation of polymer molecules in the adsorbed layers. The saturated adsorption layers of PEO are easily deformed under the action of the shear stress of the flowing solution. The effect of shear stress requires further investigation using joint measurements of the adsorption and the hydrodynamic and electrokinetic thicknesses of the adsorption layers. The thin quartz capillaries represent a simple model system with a well-characterized geometry and a Molecularly Smooth Surface. Capillary electrokinetics may effectively be used for the investigation of electroSurface phenomena in polymer solutions.

I. P. Sergeeva - One of the best experts on this subject based on the ideXlab platform.

  • Kinetics and Isotherms of Cationic Polyelectrolyte Adsorption on Quartz
    Colloid Journal, 2003
    Co-Authors: I. P. Sergeeva, V. D. Sobolev, T. B. Ermakova, N. V. Churaev
    Abstract:

    The kinetics of the formation of quartz Surface charge in the solutions of a cationic polyelectrolyte, poly(styrene- co -dimethyl aminopropylmaleimide) with the molecular mass M = 20  000 is studied in the concentration range from 10^–5 to 0.5 g/l in 10^–4 M KCl background solution at pH 6.5. Quartz capillaries with the radius from 5 to 10 μm and Molecularly Smooth Surface are used as model systems. Characteristic times of the formation of the Surface charge at equilibrium with the solution are calculated from the data on the kinetics of adsorption; these times are equal to 40–50 min for the region of electrostatic adsorption (before the Surface charge reversal) and 20–25 min, for the region of hydrophobic adsorption upon the formation of the second adlayer. Based on the steady values of the Surface charge, the isotherms and potentials of adsorption of cationic polyelectrolyte are calculated. Electrostatic adsorption isotherm is described by the Langmuir equation with the energy of molecular adsorption of 25.4 kT . It is shown that, at polymer concentration above 10^–2 g/l, the conformation of adsorbed molecules ceases to be planar. However, even in this case, we succeed in calculating the Surface charge using the Helmholtz and Gouy equations and applying the pressure drops at the capillary ends higher than 10 atm, when under the loading of increasing shear stress in the Surface layer the conformation of adsorbed molecules approaches the planar shape. Based on the two-layer model of the formation of Surface charge developed earlier, it is shown that the energy of hydrophobic adsorption is smaller than that of electrostatic adsorption and is equal to 17.7 kT . Possible physical mechanisms of electrostatic and hydrophobic adsorption of cationic polyelectrolyte molecules on quartz are discussed.

  • Adsorption layers of poly(ethylene oxide) on quartz studied using capillary electrokinetics
    Colloids and Surfaces A: Physicochemical and Engineering Aspects, 1993
    Co-Authors: N. V. Churaev, I. P. Sergeeva, V. D. Sobolev, Z. M. Zorin, E. K. Gasanov
    Abstract:

    Abstract The adsorption of poly(ethylene oxide) (PEO) molecules decreases the electrokinetic potential of a quartz Surface. The corresponding change in electrostatic forces may influence the interaction between colloidal particles in polymer solutions. The equilibrium between flowing PEO solution and adsorption layers in thin quartz capillaries is established after 1–2 h. The kinetics may be controlled by the attachment and reconformation of polymer molecules in the adsorbed layers. The saturated adsorption layers of PEO are easily deformed under the action of the shear stress of the flowing solution. The effect of shear stress requires further investigation using joint measurements of the adsorption and the hydrodynamic and electrokinetic thicknesses of the adsorption layers. The thin quartz capillaries represent a simple model system with a well-characterized geometry and a Molecularly Smooth Surface. Capillary electrokinetics may effectively be used for the investigation of electroSurface phenomena in polymer solutions.

Takeshi Serizawa - One of the best experts on this subject based on the ideXlab platform.

  • Stepwise Assembly of Isotactic Poly(Methyl Methacrylate) and Syndiotactic Poly(Methacrylic Acid) on a Substrate
    Langmuir, 2000
    Co-Authors: Takeshi Serizawa, Ken-ichi Hamada, Tatsuki Kitayama, Ken-ichi Katsukawa, And Koichi Hatada, Mitsuru Akashi
    Abstract:

    Stepwise assembly of isotactic poly(methyl methacrylate) and syndiotactic poly(methacrylic acid) from acetonitrile and mixed acetonitrile/water solutions, respectively, onto a gold substrate was studied. Quantitative quartz crystal microbalance analysis of the molar ratio (monomer unit) between assembled polymers suggested stepwise stereocomplex formation. The assembled amount and the assembly ratio between PMAA and PMAA were dependent on the acetonitrile content of the poly(methacrylic acid) solution. Infrared spectra of the assembly and cast films of each polymer also showed stereocomplex formation in the assembly. Atomic force microscopic observation showed the assembled polymer to have a Molecularly Smooth Surface. The solvent species used was an important factor in stereocomplex formation at the liquid−polymer film interface.