Miniemulsion Formation by Transitional Inversion

Abstract

Very fine emulsions with droplet size in the sub-micron range, often called miniemulsions, are prepared by the moderate (magnetic) stirring of a system undergoing a dynamic transitional inversion driven by a continuous change in physico-chemical formulation (here temperature). Near optimum formulation for three-phase systems, the ultralow interfacial tension favors the drop breaking rate, and fine emulsions can be made. However, this region is also known for its rapid coalescence rate. Thus, a high enough stability can be attained only by shifting the formulation away from optimum as soon as the emulsion is made. Moreover, a rapid change in formulation through the three-phase region also results in a separation phenomenon that can be harnessed to produce ultra fine droplets.The phase behavior of surfactant-oil-water systems and emulsion properties (type, droplet size and stability) are studied as a function of surfactant concentration (2 wt.% and 6 wt.%), for two different nonionic surfactants (polyoxyethylene triterbutyl ethers and sorbitan derivatives) with HLB ranging from 4 to 16. Kerosene and paraffin oil are used as oil phases. The transitional inversion form W/ 0 to O/W is induced by a rapid cooling of the stirred systems from above to below the optimum temperature for three-phase behavior.Miniemulsions are attained when the surfactant concentration is high enough, and when the temperature quenching span covers an appropriate range related to phase behavior.

Emulsification mechanism and storage instabilities of hydrocarbon-in-water sub-micron emulsions stabilised with Tweens (20 and 80), Brij 96v and sucrose monoesters

“…Applications studied for nano-emulsions include polymerization and other reaction processes [7,8], drug delivery [9], cosmetics [10], and novel foods [11]. A range of processes have been investigated for the production of nano-emulsions, including temperature or concentration induced phase inversion [12,13] and high-pressure homogenization processes [14]. Here, we investigate the formation of nano-emulsions in a high-pressure impinging jet device (the Microfluidizer M110-S), in order to understand the factors that limit the droplet size.…”

Intrinsic connectivity of the rat subiculum: I. Dendritic morphology and patterns of axonal arborization by pyramidal neurons

“…Because this delay occurs in both directions of change, the formulation‐composition diagram displays a hysteresis zone in which the emulsion type depends on the direction of change 5–10. However, the so‐called transitional inversion resulting from a change in formulation, including temperature, as in the phase inversion temperature (PIT) emulsification process,11, 12 generally takes place at the so‐called optimum formulation for three‐phase behaviour, whatever the direction of change and without any delay,13–15 with very few exceptions 16–18. This absence of delay is generally attributed to the high instability of the emulsion in the neighborhood of optimum formulation,19, 20 which has been explained by different mechanisms 21–23.…”

Formation and structure of slightly anionically charged nanoemulsions obtained by the phase inversion concentration (PIC) method

“…S2 †). From the value of the turbidity s we calculated the molecular weight M w of the colloidal particles according to eqn (19) 65 and converted this value to obtain an approximate particle size R for spherical particles (eqn (20)). …”

“…More recently an analogous strategy has been devised by the phase inversion concentration (PIC) method. [19][20][21][22][23] In particular, the PIC method is very appealing from a practical point of view as it only involves a simple dilution with a solvent (typically water) to produce the nanoemulsion.…”