Single, Janus, and Cerberus emulsions from the vibrational emulsification of oils with significant mutual solubility.

Single, Janus, and Cerberus emulsions are prepared in one system consisting of three oils: silicone (SO), fluorocarbon (FO) and ethoxylated trimethylolpropane triacrylate (ETPTA) with mutual solubility. An aqueous solution of Pluronic F127, which is an poly(ethylene oxide)/poly(propylene oxide) co-polymer of average composition EOPOEO, was employed as the continuous phase. The three-dimensional phase diagram of the oils was determined, and different oil compositions within the various regions of the phase diagram were emulsified by one-step vortex mixing with an F127 aqueous solution.

Janus emulsion mediated porous scaffold bio-fabrication.

A three dimensional biopolymer network structure with incorporated nano-porous calcium phosphate (CaP) balls was fabricated by using gelatin-chitosan (GC) polymer blend and GC stabilized olive/silicone oil Janus emulsions, respectively. The emulsions were freeze-dried, and the oil droplets were washed out in order to prepare porous scaffolds with larger surface area. The morphology, pore size, chemical composition, thermal and swelling behavior was studied by Scanning Electron Microscopy (SEM), Fourier Transform Infrared Spectroscopy (FTIR) and micro-Differential Scanning Calorimetry (micro-DSC).

Topical application of retinyl palmitate-loaded nanotechnology-based drug delivery systems for the treatment of skin aging.

The objective of this study was to perform a structural characterization and evaluate the in vitro safety profile and in vitro antioxidant activity of liquid crystalline systems (LCS) with and without retinyl palmitate (RP). LCS containing polyether functional siloxane (PFS) as a surfactant, silicon glycol copolymer (SGC) as oil phase, and water in the ratios 30 : 25 : 45 and 40 : 50 : 10 with (OLS(v) = RP-loaded opaque liquid system and TLS(v) = RP-loaded transparent liquid system, respectively) and without (OLS and TLS, respectively) RP were studied. Samples were characterized using polarized light microscopy (PLM) and rheology analysis.

Equilibrium topology and partial inversion of Janus drops: a numerical analysis.

The equilibrium topology of an aqueous Janus emulsion of two oils, O1 and O2, with water, W, [(O1+O2)/W], is numerically evaluated with the following realistic interfacial tensions (γ): γO2/W =5 mN m(-1) , γO1/O2 =1 mN m(-1) , and γO1/W varies within the range 4-5 mN m(-1) , which is the limiting range for stable Janus drop topology. The relative significance of the two independently pivotal factors for the topology is evaluated, that is, the local equilibrium at the line of contact between the three liquids and the volume fraction of the two dispersed liquids within the drop. The results reveal a dominant effect of the local equilibrium on the fraction of the O2 drop surface that is covered by O1.

Spontaneous emulsification between incompatible aqueous solutions in the water/ethanol/benzene system.

Two aqueous solutions on the de-mixing line in the water/benzene/ethanol system formed an O/W emulsion, when mixed. Contacting the solutions without mixing gave a slow spontaneous emulsification over several hours. The emulsion in question was found exclusively in the solution of greater water fraction and the dimension of the emulsion layer expanded as the square root of time.

Destabilization mechanisms in a triple emulsion with Janus drops.

The destabilization mechanism was investigated of a triple Janus emulsion. The inner part of the emulsion consisted of Janus drops of a vegetable oil (VO) and a silicone oil (SO) in an aqueous (W) drop, (VO+SO)/W. This drop, in turn was dispersed in a VO drop forming a double emulsion (VO+SO)/W/VO.

One-step inversion process to a Janus emulsion with two mutually insoluble oils.

High internal phase ratio (HIPR) aqueous Janus emulsions of two immiscible oils, silicone oil (SO) and a vegetable oil (VO), were prepared using a vibration mixer. The simple HIPR Janus emulsions, (VO + SO)/W, were found at weight fractions of the aqueous phase in excess of 0.3, while at a corresponding fraction of 0.

A one-step process to a Janus emulsion.

Aqueous high internal phase volume ratio (O/W 90/10) Janus emulsions of a vegetable oil and a silicone fluid were prepared in a single step emulsification by the common vibrator equipment. The basis for the unique structure is discussed in relation to pair-wise interactions between the components with especial emphasis on the surfactant concentration in the aqueous phase.

Perspectives of phase changes and reversibility on a case of emulsion inversion.

The conventional treatment of catastrophic inversion is based on a two-phase model of oil-in-water (O/W) or water-in-oil (W/O). The present investigation takes a closer look at the process of inversion with focus on its relation to the detailed phase changes in the system. It is found that phase behavior inserts a decisive call for when the inversion starts and completes, even for an inversion seemingly brought by a simple change of water-to-oil ratio.

Role of liquid crystal in the emulsification of a gel emulsion with high internal phase fraction.

A gel emulsion with high internal oil phase volume fraction was formed via an inversion process induced by a water-oil ratio change. The process involved the formation of intermediate multiple emulsions prior to inversion. The multiple emulsions contain a liquid crystal formed by the surfactant with water; this was both predicted by the equilibrium phase diagram as well as observed using polarization microscopy.

Phase diagram approach to evaporation from emulsions with n oil compounds.

The initial evaporation path was calculated for an emulsion of water and a multicomponent oil phase under the following conditions. The computations were based on the phase diagram of the emulsion system combined with an algebraic system to extract information from phase diagrams to facilitate the mathematical treatment. An inherent consequence of the use of the phase diagram as a basis to calculate an evaporation path is the condition of equilibrium between the phases in the emulsion as well as between the vapor and the condensed phases.

Effect of relative humidity on the evaporation path from a phenethyl alcohol emulsion.

The evaporation path for emulsions of phenethyl alcohol stabilized by a non-ionic surfactant, Laureth 4, a commercial ethoxy adduct, approximately C(12)(EO)(4), was estimated by calculations using the phase diagram. The results for emulsions with an O/W ratio equal to or greater than 1/3 showed the relative humidity only in excess of 90% to have a significant effect on the evaporation path. In fact the path was not significantly modified for relative humidities from 0% to 90%, but in the range 90-100% the modification of the evaporation path was most pronounced; not only altering the path, but causing entirely different phases to appear in the emulsion.

Geranyl acetate emulsions: surfactant association structures and emulsion inversion.

Three emulsions of geranyl acetate (GA)-in-water (W) with identical GA/W ratios and varying surfactant (S), Laureth 4, a commercial C(12)EO (4) compound, fractions were investigated for nature and stability. The emulsions with up to 6% surfactant were W/O, as expected with respect to the solubility of the surfactant in the oil. At 10% surfactant, the aqueous phase became the continuous one and the apparent stability of the emulsion was significantly enhanced.

Constant vapor pressure emulsions evaporation: Linalool/water stabilized by Laureth 4.

Evaporation paths were calculated in the title system using the relevant part of its published phase diagram and the assumption of equilibrium between vapor and liquids. The vapor pressure of linalool was reduced while the emulsion resided in the two-phase region but remained constant within the three-phase range. The duration of the time for constant vapor pressure depended on the relative humidity (RH) to a surprising degree.

A simple analysis of the changes during evaporation of a commercial emulsion of unknown composition.

Optical microscopy and centrifugation were used to observe the structural changes during evaporation of a commercial skin lotion of unknown composition. The degree of evaporation was determined from the changed weight of a microscope slide with the emulsion on a defined area and thickness, the evaporation loss versus time being measured by a balance under an infrared lamp. The results revealed not only which parts of the emulsion were most prone to evaporation without chemical analysis, but also gave surprising information as to which kind of structures would appear after extensive evaporation.

Evaporation from an ionic liquid emulsion.

The conditions during evaporation in a liquid crystal-in-ionic liquid microemulsion (LC/microEm) were estimated using the phase diagram of the system. The equations for selected tie lines were established and the coordinates calculated for the sites, at which the evaporation lines crossed the tie lines. These values combined with the coordinates for the phases connecting the tie lines were used to calculate the amounts and the composition of the fractions of the two phases present in the emulsion during the evaporation.

Some non-equilibrium phenomena in the malic acid/water/Polysorbate 81 system.

Topical formulations undergo radical structural changes after application and the action on the skin is not directly related to the original structure of the formulation. This fact has been well established in the scientific literature. However, and more essential, is the fact that these changes in the formulation structure are not equilibrium ones.

Some pertinent factors in skin care emulsion.

Emulsion structures are reviewed with special consideration given to the conditions in emulsions for topical applications with more phases than the traditional two liquids. The fundamentals of emulsions containing liquid crystals and vesicles are described, focussing on the dependence of the volume ratios of liquid crystals and vesicles on the surfactant content.

Phase behavior of beta hydroxy-acids with laureth 4.

The colloidal structures of beta carboxylic acid topical vesicle formulations were determined and the changes during evaporation after applications were estimated from phase diagrams. The results showed significant difference during evaporation between salicylic acid on one hand and three water soluble acids; malic, tartaric, and citric acid, on the other. The water soluble acids showed an increase in the acid concentration in the aqueous solution to levels that must be considered harmful, while salicylic acid showed no increase in concentration in the individual phases even after 99% evaporation of water.

Analytical expressions to calculate relative amounts of phases in a three-component phase diagram.

The relative amounts of different phases in multiphase regions in the common three-component phase diagrams are usually estimated graphically using geometrical features of the diagram. The present contribution introduces algebraic expressions for the lines in the diagram, which allow these numbers to be calculated directly from the experimental results. The method is an extension of the classical methods, which were translated into convenient computer programs [Laughlin, R.

Phase behavior of the alpha-hydroxyoctanoic acid/Laureth 4/white oil/water system and preliminary evaluation of the phase changes during evaporation of its emulsion.

The phase diagram was determined for the alpha-hydroxyoctanoic acid/Laureth 4/white oil/water system using visual observation with an optical microscope. Typical emulsions were evaporated to determine the structural changes. These were compared to those predicted from the phase diagram.

The Hydrotrope Action of Sodium Xylenesulfonate on the Solubility of Lecithin.

The activity of sodium xylenesulfonate in aqueous solution was determined by vapor pressure measurements, the results of which were transformed to mean activities. In addition, surface tension, conductivity, and partial molar volume were determined to obtain complementary information about potential association structures. No sudden change was observed, indicating the association to take place in the concentration range where the increased solubility of lecithin was observed, contrary to the case of surfactant micellization.