Changes of mesophase structure of BRIJ 96/water mixtures on addition of liquid paraffin

Abstract

The influence of the addition of liquid paraffin (LP) on the structure of the lamellar (L~) and hexagonal (H1) mesophases formed in mixtures of water (W) and BRIJ 96 (/3) was studied. Mesophases were identified using polarization microscopy and small angle x-ray diffraction (SAXD). Repeat spacings were also determined with SAXD. Depending on the W/B ratio, addtion of LP to L~ gives a large, almost linear one-dimensional swelling or an initial swelling followed by a gradual transition to H1. L~ with a high LPcontent gives a diffraction pattern showing only the first order diffraction maximum, possibly a result of undulations of the layers. The lamellar structure, however, was confirmed using freeze fracture electron microscopy (FFEM). Addition of LP to H1 gives an initial swelling followed by a transition to a transparent, highly viscous, isotropic phase, called the gel-phase (G). The diffraction pattern obtained from G yields little information on its structure. A large swelling of G with LP was observed. From the degree of swelling as a function of hydrocarbon content it was inferred that this phase consists of spherical aggregates forming a close-packed structure. Using FFEM, textures were visualized resembling those obtained from the isotropic mesophase (I1) in water-surfactant mixtures. Finally, geometrical factors are discussed that may play a role in the formation of the gel-phase.

Freeze-fracture electron microscopy study of mesophases in mixtures of polyoxyethylene (14) oleylether and water

“…Mostly textures characteristic of the lamellar phase are seen everywhere on the replicas. The repeat spacing of the layers observed in the micrographs is about 6 nm, which is in good agreement with findings from X-ray diffraction [18]. Most fracture planes are parallel to the lamellae (Fig.…”

“…In some places though, fracture planes without the ribbed pattern may be seen and the texture resembles that of the lamellar phase. The average distance between the rods, determined from the ribs in the fracture planes, is about 8 nm and in good agreement with findings from X-ray diffraction [18]. Cross fractures are frequently observed, showing end views of the rods in hexagonal array (Fig.…”

Cubic-Phase-Based Concentrated Emulsions

“…It is probable that oils stabilize the cubic phase by inducing the formation of micelles with a moderate axial ratio and, therefore, a more positive curvature (12,(25)(26)(27)(28)(29). This may improve the packing and order of micelles in the cubic structure so that the I 1 -W m phase transition temperature increases.…”

A structural study of the mesophases of two oxyethylene alkyl ether-decane-water systems, a comparison between technical grade C12EO〈7〉 and pure C12EO6

“…A relationship can be derived between the weight fractions of the components used and the repeat distance [25] K~ Mostly the first and second order peaks can be detected.…”