Brij 97, phase diagram

Hgure 6.38 Partial phase diagram for the Brij 97 (CigHjj (OCH2CH2)ioOH)-water-mineral oil solubilised system. 

A simple but illustrative example is the combination of phenethyl alcohol with water and a nonionic surfactant polyoxyethylene (4) lauryl ether (BRIJ 30). Figure 2 shows the W/O microemulsion region to be in equilibrium with a lamellar liquid crystal and a dilute aqueous solution of the fragrance for a large part of the entire phase diagram. This means that the vapor pressure of the phenethyl alcohol remains constant during evaporation as long as the total composition remains within the area ABC of Fig. 2. 

Figure 2 The phase diagram for the system water-laureth-4 (BRIJ 30)-phenethyl alcohol. L2 is a water-in-oil microemulsion LLC is the lamellar liquid crystal and A, B, and C define the three-phase region. The dashed line represents the evaporation path through the three-phase region into the LLC and W/O microemulsion region.

Figure 10 Phase diagram of a simple fragrance compound system (phenethyl alcohol) with water and a commercial non-ionic surfactant (Brij 30) (see text).

FIG. 11 Phase diagram for the system dodecane + butanol 1 1 (w/w)-Brij 97-water at 27°C. Along the XB4 water dilution line, the Brij 97/butanol/dodecane weight ratio is 4 3 3. LC designates the liquid crystalline phase region. (From Ref. 67.)... 

FIGURE 6.10 Evolution of ternary phase diagrams of the Brij 35/aIcohol/water system with change in the alcohol from ethanol to 1-decanol at 25°C. Gray lines indicate the composition lines of the studied samples with 5% of Brij 35. (Reproduced from Touraud, D., Contribution h I tude de microemulsions utilisables comme milieux reactionnels (thesis). CompiSgne Universite de Technologie de Compi gne, 1991. With permission.)... 

Extensive studies on the influence of the nature of the oil phase on the phase behaviour of the Brij 96-oil-water systems have been reported [34, 35]. The considerable influence of the oil phase on the aspect of the phase diagram is apparent from Fig. 2.16 which shows the phase behaviour for nine different oils. In Fig. 2.17a the percentage uptake of water into different isotropic L2 phases containing 50 per cent Brij 96 is plotted against the dielectric constant e of the oil... 

Figure 2.16 Phase diagrams for Brij 96-oil-water systems for the oil as shown. The phases identified include the L, L2, E, Mj, and G phases as noted before and also an isotropic elastic phase (e) and an isotropic elastic phase containing dispersed globules of oil (oe).

Figure 2.18 Phase diagrams for Brij 96-water-vegetable oil ternary systems, for the following oils (a) sweet almond oil (b) maize oil (c) castor oil. From Kabbani et al [34] with permission.

The influence of the hydrophile-lipophile balance (HLB) of the non-ionic surfactant on the phase behaviour has recently been studied [34-37] with the aim of better understanding the mechanisms of emulsion and suspension stabilization. Ternary phase diagrams for dodecane, water and mixtures of Brij 92, and Brij 96 (polyoxyethylated oleyl alcohol derivatives with oxyethylene chain lengths of 2 and 10, respectively), with a range of HLB values, are shown in Fig. 2.19. The areas of the L2 and the inverse middle phase M2 (an interesting feature of these systems not usually observed in polyoxyethylene non-ionic systems) increase as the HLB increases, reaching a maximum at HLB 8. Maximum water uptake in the L2 phase in 25 %, 40 % and 50 % surfactant solutions in oil as a function of HLB is... 

Figure 2.19 Phase diagrams of dodecane-water-Brij 92/96 mixtures. 0,W,S = 100% oil, water, surfactant, respectively. HLB values of the surfactant mixtures are shown to the right of each diagram. Phase boundaries for Li, L2, G, and M2 phases shown. Other symbols represent 2L, two-phase oil-water system (emulsions of varying stability) M, microemulsion I, isotropic elastic I +, isotropic elastic + disperse oil phase. Filled black regions stable emulsion zones. From Lo et al. [37] with permission.

Figure 8.31 Hypothetical phase equilibria diagram showing regions of microemulsions and micellar solutions, after Prince [167]. This simplified phase diagram has been criticised by Ranee and Friberg [165] but diagrams with the construction shown above have been obtained by Lo et al. [146] as shown in the insert to the figure, which illustrates the Brij 96-isopropyl myristate-water system at room temperature (oe represents a viscous phase of surfactant containing dispersed oil).

Figure 9 Effect of the addition of alcohol and cosolvent on the phase diagiam T = 25°C). (a) Three-component diagram water, limonene, and surfactant (Brij 96). (b) Effect of ethanol addition, (c) Effect of ethanol and propylene glycol addition.

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