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Both normal and reverse vesicles can be formed in the mixture of sucrose dodecanoates with different hydrocarbon chain number. The conditions to produce both types of vesicles are discussed using the geometrical packing model. The conditions are roughly the same for both types of vesicles. The formation of reverse vesicles is confirmed by means of video-enhanced microscopy (VEM) and cryo-transmission...
The isothermal ternary phase diagram for the 1-dodecyl pyridinium bromide-water-dodecane surfactant system has been determined at 40 °C by 2H NMR and polarizing microscopy methods. For the binary surfactant-water system, a normal hexagonal liquid crystalline phase and an isotropic normal micellar solution phase are identified. On addition of dodecane, a new isotropic cubic liquid crystalline phase...
Ternary systems sodium dodecylsulphate (SLS)/n-alcohol/water with alcohols of different chainlengths and a constant water content of 55% have been investigated by polarized optical microscopy and small-angle x-ray scattering. Upon addition of cosurfactant a hexagonal phase with constant lattice parameter transforms via a two-phase region into a lamellar phase. If surfactant and cosurfactant have similar...
Phase behavior, surfactant self-diffusion coefficients (D) and small-angle x-ray scattering (SAXS) have been measured on concentrated solutions of a nonionic surfactant (C16E7) where entanglement of wormlike micelles has been suggested in our previous light scattering study. In the lower temperature range, the self-diffusion coefficient/activation energy for self-diffusion processes (ED...
A thermodynamic theory for ideally mixed rodlike micelles is used to predict the size distribution and mean aggregation number of mixed dihexanoylphosphatidyl-choline (diC6PC) and diheptanoyl-phosphatidylcholine (diC7PC) micelles. The mixed diC6PC and diC7PC micelles are also studied by small-angle neutron scattering. The measured neutron scattering spectra are analyzed to give the size distribution...
Phase behavior of sodium cholate/calcium chloride mixture strongly depends on both molar ratio and actual concentration of each component. Phase diagram exhibits precipitation regions where mixture of several kinds of solid crystalline and liquid crystalline phase coexist and regions where micelles are formed. Considerable variation of properties is caused by different arrangements of cholate anions...
The destabilization of phosphatidylcholine bilayer membranes by the bile salt sodium deoxycholate was studied from steady-state fluorescence anisotropy measurements. FATVET liposomes of DPPC composition were prepared by sequential extrusion through polycarbonate membranes and characterized for their overall inner volume, average size and size distribution, and lamellarity. Interactions between acyl...
The molecular organization in lamellar mesophases was proposed on the basis of dynamic and static light scattering, polarizing and transmission electron microscopy, and x-ray diffraction measurements. The basic symmetries of the dynamics of formation and structures of the lamellar bilayers and multilayers of the surfactants of alkylbenzene-sulphonate series were found to be consistent from the beginning...
The report is concerned with the functioning of ion-selective electrodes responding to surface-active agents in solutions of aggregated surfactants. Contrary to the current mechanisms destined for inorganic sensors, it has been suggested that adsorbed species and surface aggregates (hemimicelles and admicelles) on the membrane surface are essential factors in the response and functioning of surfactant...
We have studied micelle formation of two series of D-glucose amphiphilic derivatives: 3-deoxy-S-alkyl-1,2-O-isopropylidene-α-D-glucofuranose, marked MAG-Sn and 3-deoxy-S-alkyl-D-glucopyranose, marked GLU-Sn, where n is the carbon atom number of the alkyl chain R in the alkyl group (R=n-CnH2n+1; n=8, 12, 16, 18). CMC in water and corresponding surface tension γ have been determined at 25°, 30°, 40°...
Traditionally, surfactant research in industry has relied almost exclusively on experiments. Lately, we have attempted in our laboratory to use computer simulations to complement this experimental effort. Molecular dynamics and Monte Carlo techniques have now become an integral part of surfactants and fluids research, not only offering new insight (primarily of interest to academia), but also enhancing...
We investigate the structure and the osmotic pressure versus concentration of a colloidal crystal of charged bromopolystyrene particles of diameter 100 nm. In a concentration range between 2 and 12% volume fraction and in the presence of ion exchange resin which fixes a very low (micromolar) salt concentration, a colloidal crystal is obtained. The packing structure evidenced via Ultra-Small-Angel...
The behaviour of small charge-stabilised particles (A, radius 168 Å) in the presence of larger particles (B, radius 510 Å) in 6 × 10−5 mol dm−3 sodium chloride solution has been investigated using small-angle neutron-scattering. The number concentration ratio, NA/NB, used was 15. The results indicated that the particles remained colloidally stable in the mixture but that some...
Aqueous suspensions of Polytetrafluorethylene (PTFE) rod-like particles have been studied by electric light scattering at different particle concentrations (0.05–4% w/w) and degrees of dialysis. For particle concentrations 1 and 4% w/w the electric light scattering effect changes its sign from positive to negative when going to lower frequencies at low electric field strengths for both undialyzed...
We report the first preliminary two photon Rayleigh scattering measurements done at 1.064 µm in micellar and microemulsion systems as a function of the molar water-to-surfactant ratio value (ω0) and volume fraction (φ) of the droplets. They provide the β values of the static quadratic hyperpolarizability of BHDC surfactant molecule dissolved in water and heavy water as well as those of...
We have studied the influence of the surface charge density of polymer colloids on aggregation processes induced at a high salt concentration. In this way, the effect of the residual interaction between the particles on the aggregation mechanism was studied. The time dependence of the detailed cluster-size distribution and the time-independent scaling distribution were obtained by single particle...
Spherical colloidal silica particles coated with stearyl alcohol and dissolved in benzene show a temperature dependent attraction which gives rise to a gas-liquid critical-point. The attraction is due to the fact that benzene is a marginal solvent for the stearyl alcohol. Close to the critical-point, spatially extended structures exist, which are characterized by the correlation length. A shear...
Core-shell latex particles with surface-acetal functionality were synthesized for use in immunodiagnostic testing. By acidification of the acetal groups to aldehydes, covalent bonding with the aminogroups of biomolecules is possible. Acetal functionality was chosen due to the chemical instability of the aldehyde group. The synthesis of this kind of particles was carried out by a two-step emulsion...
To investigate the morphology of individual latex particles with the atomic force microscope the particles were adsorbed onto mica and then dried. During adsorption and subsequent drying the packing of the particles is probably mainly determined by capillary forces, their deformation is caused by van der Waals forces. The shape of the particles on the mica surface depends on their original morphology...
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