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The traditional methods of determining zeta potentials (particle electrophoresis, streaming potential and electroosmosis) all suffer from real drawbacks in the matter of reliability. Measurements on very dilute systems (using, say, microelectrophoresis) are prone to contamination problems, but even when the direct current mobility is accurately assessed, current estimates of zeta potentials can be...
It is shown that the electrophoretic mobility μ of dilute spherical colloidal particles of radius a, carrying charge Q in a salt-free medium (containing only counterions) is expressed generally as μ=Qeff/DH, irrespective of the particle type, where Qeff is the effective particle charge and DHis the drag coefficient of the particle. There is a certain critical value of Q separating two...
We distinguish two kinds of nonlinear electrophoresis that can be observed in strong electric fields. The first is due to the interaction of the applied field E with the field-induced ionic charges, under conditions when the field-induced variation of the electrolyte concentration remains small compared to its equilibrium value. The second one (“superfast electrophoresis”) is related to the interaction...
This work presents a theoretical analysis of the relation between the tube zeta potential and the electrolyte solution composition typically found in capillary electrophoresis. A model including the relevant physicochemical parameters of the capillary–solution interface is derived in the framework of Poisson–Boltzmann theory and is then validated experimentally. This model is applied to capillaries...
We calculate the steady-state electric birefringence for a flexible bent rod molecule due to free electrophoresis and the interaction of its induced dipole moment with an externally applied electric field. We consider the solution of flexible bent rod as a mixture of rigid bent rod molecules with different angles of conformation. We use the Fokker–Planck equation in order to find the orientational...
Adsorption of oxalate and chromate onto hydrous chromium(III) oxide and onto α-Cr2O3 was studied by spectroscopic methods (Fourier transform IR) and by measurement of electrophoretic mobilities. The Fourier transform IR spectra demonstrate the formation of surface complexes, and also the surface dimerization of chromate to give surface-bound dichromate. The mobility profiles are interpreted in terms...
Systems are reviewed in which spontaneous nonlinear oscillations occur at the interface by surfactant transfer inside the system. Oscillations of the electrical potential through the interface and of the interfacial tension were observed by transfer of ionic species through an oil/water interface and through a liquid oil membrane interposed between two aqueous solutions. Auto-oscillations of the surface...
The purpose of this contribution is to analyse the surface forces and the stability of thin-layer systems falling outside the Derjaguin–Landau– Verwey–Overbeek theory. It is shown that peculiarities of fluid behaviour in a confined geometry allow one to understand the origin of the previously mentioned phenomena. Emphasis is placed on the liquid interlayers constituted from molecules possessing internal...
The investigation of two- or three-phase boundaries is an essential part in the study of different surface phenomena like surface tension, contact angles, wetting hysteresis, swelling, and flotation. At present, the most accurate methods to investigate these parameters are based on the digital image processing of interfacial profiles. In this paper we describe several methods employing the digital...
The contact angles of liquid drops on inclined plane surfaces have been investigated at critical conditions of sliding. Drops of two liquids were tested on eight surfaces covering a wide range of advancing and receding contact angles. Contact angles and contact line dimensions were observed for various drop sizes and surface inclination angles. The contact-angle variation along the circumference of...
The combination of two in situ techniques for the study of immobilization of biomolecules is seldom performed. Therefore, the combination of in situ ellipsometry with atomic force microscopy (AFM) in a liquid was used to follow the adsorption process of enolase, an enzyme of the glycolytic pathway. The adsorbed amount and topographic information of the adsorbed layers were obtained in the liquid environment...
Block copolymers, poly(3,5-bis(3,5-bis(benzyloxy)benzyloxy)benzyl methacrylate-random-methacrylic acid)-block-poly(2-perfluorooctylethyl acrylate) [P(D3MA,MAA)-b-PFA], which contain benzyloxy dendron and perfluorinated alkyl chains in their side chains, were synthesized. The products were characterized by differential scanning calorimetry and IR absorption spectroscopy, and their degrees of polymerization...
When a dilute dispersion of relatively monodisperse silica particles is dried on a solid substrate, close-packed arrays are formed. The ordering of the particles results from attractive capillary forces between neighboring particles, and convective transport of particles to the ordered domain during drying. In the presence of adsorbed polymer layers on the particles, the close-packed arrays are disrupted...
We report a molecular dynamics computer simulation study of the liquid/liquid interface formed by water and carbon tetrachloride (H2O/CCl4) at 298 K. The primary focus of the work is the characterization of the structural features of the interface at a molecular level. The computed density profiles for the aqueous and organic phases and the distribution of surface widths indicate a fairly smooth interface...
Polymers of great commercial use such as polyethylene, polypropylene and polystyrene have had their surface properties modified. Many researchers have recently altered the properties of polymers via grafting reactions. In this work, the surface of low-density polyethylene (LDPE) submitted to grafting with maleic anhydride followed by hydrolysis, chlorination, amination and protonation reactions was...
The steady-state fluorescence technique was used for studying dissolution of UV-cured polymer films. These films were formed from poly(methyl methacrylate) chains labeled with pyrene which was introduced as a fluorescence probe to monitor the dissolution processes. Poly(methyl methacrylate) films with various ethylene glycol dimethacrylate contents, cured by UV radiation for 3 and 25 h, were dissolved...
The nanometer-scale organization of collagen (type I) adsorbed on polystyrene (PS) and plasma-oxidized PS (PSox) was investigated using atomic force microscopy (AFM) as well as radioassays and X-ray photoelectron spectroscopy. The surface properties induced by plasma treatment of PS were examined: PSox was more hydrophilic than PS, owing to oxygen incorporation, and was covered by a layer of polyelectrolyte...
The behavior of liquid molecules confined in nanometer-scale spaces is quite different from that in the bulk. The structuring of liquids confined between solid surfaces was investigated using a shear force resonance method, which was developed in order to examine in detail the ordering behavior of liquid molecules confined between two mica surfaces. The frequency and the amplitude of the resonance...
Nickel ferrite nanoparticles are synthesized bottom up and then peptized in aqueous media resulting in stable magnetic fluids. X-ray powder diffraction and transmission electronic microscopy permit the investigation of the crystalline structure and the morphological aspects of the nanoparticles. Magnetic and magneto-optical properties of the resulting materials are investigated by static measurements...
Nanocomposites have been prepared through the intercalation of poly(amido amine) dendrimers with carboxylate terminals into hydrotalcite clays. The formation of nanocomposites by anion exchange during incubating at 70 °C was investigated at various compositions with increasing dendrimer content in water and was assessed by Fourier transform IR absorption spectroscopy, X-ray diffraction, small-angle...
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