Physical and chemical stability of β-carotene-enriched nanoemulsions: Influence of pH, ionic strength, temperature, and emulsifier type.

Formation of nano-emulsions has been studied in the system water/Brij 30/decane at 25 °C by three low-energy emulsification methods:  (A) stepwise addition of oil to a water−surfactant mixture, (B) stepwise addition of water to a solution of the surfactant in oil, and (C) mixing all the components in the final composition. Nano-emulsions with average droplet size of 50 nm and high kinetic stability have been obtained only at oil weight fractions, R, lower than 0.3 by emulsification method B. Independent of the oil weight fraction, R, emulsions obtained by method B have lower polydispersity than those obtained by methods A and C. Phase behavior studies have revealed that compositions giving rise to nano-emulsions consist of Wm, (O/W microemulsion), Lα (lamellar liquid crystalline), and O (oil) phases, at equilibrium. It has been shown that equilibrium properties cannot fully explain nano-emulsion formation. Low values of equilibrium interfacial tensions and phase equilibrium involving a lamellar liquid cry...

Formation of Nano-emulsions by Low-Energy Emulsification Methods at Constant Temperature

Characterization of starch by size-exclusion chromatography: The limitations imposed by shear scission

Oil/water (O/W) nano-emulsions have been formed in the system water/C16E6/mineral oil by the phase inversion temperature (PIT) method. The relation between the phase equilibria observed at the hydrophilic−lipophilic balance (HLB) temperature or the PIT (i.e., the nature, number, and relative volume fractions of the involved phases), the droplet sizes, and polydispersities of the resulting emulsions have been determined. Milky white emulsions were obtained when, at the HLB temperature, a three-phase equilibrium formed by water (W), shear-birefringent microemulsion (D), and oil (O) was observed. However, bluish transparent O/W nano-emulsions with droplet sizes as low as 40 nm were formed in a narrow range of oil-to-surfactant ratios in which a D or W + D phases were the initial equilibrium phases. In the W + D equilibria, droplet sizes were independent from the water content, indicating that nanodroplet formation is mainly controlled by the structure of the D phase. These results suggest that the main requi...

A Study of the Relation between Bicontinuous Microemulsions and Oil/Water Nano-emulsion Formation

An updated review on suspension polymerization is presented. The time period from 1991 to 1995 is stressed, as well as research articles or reports not considered in previous reviews. Our review is aimed at providing a sound basis for the theoretical background required to build an effective model for the particle size distribution (PSD) in suspension polymerization. All major phenomena that affect the PSD are considered, and a proposed approach to develop an accurate, yet simple, model is included. Most of the experimental information in this review is related to the styrene/divinylbenzene copolymerization system, although the ideas and models are not exclusive to this system.

An Updated Review on Suspension Polymerization

Properties of surfactant/oil/water emulsified systems in the neighborhood of the three-phase transition

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/O 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.

Miniemulsion formation by transitional inversion

Analysis of polyethoxylated surfactants in microemulsion-oil–water systems: III. Fractionation and partitioning of polyethoxylated alcohol surfactants

All variables capable of altering the physico-chemical formulation, including temperature, are included in a generalized concept known as the hydrophilic-lipophilic deviation (HLD), which measures the departure from the reference state at which the surfactant-oil-water system exhibits Winsor III three-phase behaviour. The general phenomenology representing the emulsion properties (type, stability, viscosity, drop size) can be qualitatively charted in a three-dimensional map, where each region exhibits definite features. Travelling across the map from one region to another corresponds to modifications in formulation, composition and stirring along a path which can describe the protocol of change in an industrial process dealing with emulsion making, inversion or reworking. Six different path cases, labelled as unit operations, emerge from a systematic categorizing, and allow the interpretation of complex industrial processes such as crude oil dehydration, or the manufacturing of paint, cosmetics or heavy hydrocarbon emulsions.

J. L. Salager

Papers

Properties of surfactant/oil/water emulsified systems in the neighborhood of the three-phase transition

Miniemulsion formation by transitional inversion

Analysis of polyethoxylated surfactants in microemulsion-oil–water systems: III. Fractionation and partitioning of polyethoxylated alcohol surfactants

The emergence of formulation engineering in emulsion making—transferring know‐how from research laboratory to plant

Breaking of a cationic amine oil-in-water emulsion by pH increasing: Rheological monitoring to modelize asphalt emulsion rupture