Phase inversion catastrophic

Rgure 1.6. (a) Schematic formulation-composition map. SAD is the surfactant affinity difference it is positive for a lipophilic surfactant and negative for a hydrophilic one. The gray zones are abnormal, (b) Schematic representation of the proposed mechanism for a transitional inversion, (c) Schematic representation of the proposed mechanism for a catastrophic phase inversion. 

J.L. Salager Properties of Emulsions at the Onset of Catastrophic Phase Inversion in the Normal to Abnormal Inversion. In Proceedings of the 3rd World Congress on Emulsions l-F-185, Lyon, France (2001). 

A.W Nienow Breakup, Coalescence and Catastrophic Phase Inversion in Turbn-lent Contactors. Adv. Coll. Int. Sci. 108-109, 95 (2004). 

S. Sajjadi, F. Jahanzad, and M. Yianneskis Catastrophic Phase Inversion of Abnormal Emulsions in the Vicinity of the Locus of Transitional Inversion. Colloid and Surfaces A Physicochem. Eng. Aspects 240,149 (2004). 

Figure 15.23. Catastrophic phase inversion, (a) If one slowly adds phase B to phase A, inversion takes place at a high volume fraction of B. (b) If one add phase B more quickly,...

Catastrophic phase inversion is used with products that naturally occur as oil-in-water emulsions, but are to be used as water-in-oil emulsions (butter, margarine). It is also an effective way of preparing emulsions with a dispersed phase that is high-viscous. However, the final droplet size is usually not very small, and the emulsion can be rather poly disperse. 

GEJ Vaessen. Predicting catastrophic phase inversion in emulsions. PhD dissertation, Eindhoven University of Technology, Netherlands, 1996. 

Kralchevsky, P.A., Ivanov, I.B., Ananfhapadmanabhan, K.P. and Lips, A. (2005) On the thermodynamics of particle-stabilized emulsions curvature effects and catastrophic phase inversion. Langmuir, 21, 50-63. 

A third class is phase inversion. Here, emulsions are made by starting with an emulsion in which the ultimate continuous phase is the dispersed phase and vice versa. Then by adding more and more dispersed phase, one can induce the emulsion to suddenly invert (catastrophic inversion). Alternatively, one can choose the surfactant system such that, for example, by a temperature change, the surfactant system changes from favouring the initial emulsion to favouring an inverted emulsion. This is called transitional phase inversion. 

Brooks, B.W. Richmond, H.N. Phase inversion in non-ionic surfactant-oil-water systems. II. Drop size studies in catastrophic inversion with turbulent mixing. Chem. Eng. Sci. 1994, 49, 1065-1075. 

The phase inversion of emulsions can be one of two types (i) transitional inversion, which is induced by changing facers which affect the HLB of the system (e.g., temperature and/or electrolyte concentration) and (ii) catastrophic inversion, which is induced by increasing the volume fraction of the disperse phase. 

In liquid-liquid systems, upon increase of concentration of the dispersed phase, at a certain concentration suddenly the dispersed and continuous liquids exchange roles. This is known as a phase inversion. Salager et al. [1983] and Minana-Perez et al. [1986] reported two types of phase transition in ionic emulsions — in the first, viscosity goes through a minimum, whereas in the second it goes through a maximum. The first type of transition (normal) is associated with a decrease of the interfacial tension coefficient and formation of a micro-emulsion. The second (catastrophic) transition is associated with an inversion of unstable structure to a stable one. 

Alternatively, the dispersion can be subjected to a well-prescribed deformation, characterized by its rate and type (deformation state variables, DSVs) in order to invert the dispersion under constant thermodynamic conditions this phenomenon is known as FIPI. It is found that FIPI is not catastrophic and the dispersion goes through an unstable co-continuous state denoted by [AB], followed by a relatively stable multidispersion state denoted as [A-in-B]-in-A, before complete phase inversion to [B-in-A]. Therefore, the interchange ability of TSVs with DSVs forms the basis of FIPI processes. 

Salager, J. L., Phase inversion and emulsion inversion on the basics of catastrophe theory, in Encyclopedia of Emulsion Technology, Vol. 3, Becher, P. (Ed.), Marcel Dekker, New York, 1983, pp. 79- 134. 

Two types of phase inversion may be distinguished (a) Catastrophic, e.g. when the disperse phase volume exceeds its maximum packing and (b) transitional, which occurs over a long period of time due to change in the conditions. An example of transitional phase inversion is when the emulsion is subjected to a temperature change. For example, when an emulsion, prepared using an ethoxylated nonionic... 

Drops present before catastrophic inversion. When the catastrophic inversion is brought about by the addition of the aqueous phase to the oil phase (high HLB), two drop types can be present before phase inversion ... 

Figure 15.24 schematically shows a state diagram of the system. Compositions left of the nodal curve will be a B-in-A emulsion, when more A is added, (catastrophic) inversion will take place at the modal line. However, in a specific area where the affinity of the surfactant system towards both phases is approximately equal, transitional inversion may take place. 

Figure 2.5 shows also the concentration dependence of the inverse Kauzmann temperature T (entropy catastrophe temperature). For the pure metal, T is much higher than the temperature T0 as discussed. The 77-line should also decrease with increasing concentration and end in the triple point(C, 7 )[2.21] as follows from its definition (AS = 0). It is interesting to note that at this point the real Kauzmann temperature and the inverse Kauzmann temperature meet. But in real systems, the amorphous phase has an excess entropy (small fraction of the entropy of fusion) when compared to the corresponding crystal, the exact amount determined from the kinetics and timescale of the glass transformation. Therefore, another glass transition temperature line with finite excess entropy must be considered, which will be parallel to the Tg-line (above it) and cross the T0- and 77-lines not exactly in the triple point. 

Salager JL. Phase transformation and emulsion inversion on the basis of catastrophe theory. In Ref. 4 79-134. 

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