Evaporation from microemulsions

Friberg, Stig E.; Yu, Boping; Lin, John W. P.; Barni, Ermanno; Young, Timothy M.

doi:10.1007/bf00651818

Cited by 19 publications

(6 citation statements)

References 16 publications

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“…Not surprisingly all batches of Brij 96 were found to contain very small amounts of a more lipophilic compound corresponding to oleyl bromide and a more hydrophilic compound assumed to be polyoxyethylene glycol. 1 H NMR of the surfactant in CDCl3 determined at 298 K using a Perkin-Elmer R32 (90 MHz) spectrometer gave a ratio of alkyl: polyoxyethylene protons that yielded an average ethylene oxide content per hydrophobe that showed reasonable agreement with the ethylene oxide content stated by the manufacturer (assuming no variation in the alkyl chain content). Triple distilled water, obtained from a well seasoned all-glass still, was used through out.…”

Section: Methodssupporting

confidence: 52%

“…In all the samples tested, PCS verified the presence of aggregates, ranging in size from a few nanometers to 100 nm, well within the size range of 2.5-150 nm quoted by Friberg for microemulsion droplets. 1 Note, that due to the concentrated nature of the microemulsion samples tested, the sizes determined by PCS will be affected by interparticulate interference and as a consequence cannot be regarded as true estimates of droplet size, and in this study therefore they were used only to confirm the existence of o/w microemulsions.…”

Section: Resultsmentioning

confidence: 99%

“…While it is well-recognized that microemulsions may form a number of different structures (e.g., oilin-water or water-in-oil droplets, bicontinuous structures) over a wide range of compositions, considerable debate exists over a universally accepted definition of a microemulsion. This is due to the fact that some workers dispute the validity of the term microemulsion when applied to systems containing either low volume fractions of oil or water, suggesting instead that it is more appropriate to refer to the system as a (swollen) micelle, 1 reserving the term microemulsion for systems in which there is sufficient dispersed phase incorporated into the surfactant aggregate such that it can be considered to have the properties of its bulk. Others argue, however, that there is no difference between a microemulsion and a solute-swollen micelle and that the term micellar solution should only be applied to systems containing just surfactant in solvent.…”

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Effect of Oil on the Level of Solubilization of Testosterone Propionate into Nonionic Oil-in-Water Microemulsions

Malcolmson¹,

Satra²,

Kantaria³

et al. 1998

Journal of Pharmaceutical Sciences

154

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The level of solubilization of the drug testosterone propionate into 2% w/w oil-in-water (o/w) microemulsions, stabilized by the nonionic surfactant polyoxyethylene 10-oleyl ether (Brij 96) and containing a range of oils, has been determined. Although testosterone propionate was readily soluble in the ethyl esters ethyl oleate, ethyl caprylate, and ethyl butyrate, and the triglycerides soybean oil, Miglyol 812, and tributryin, and the alkene 1-heptene, only microemulsions containing the ethyl esters and the triglyceride oils exhibited a significant increase in solubilization over the corresponding micellar solution (i.e., surfactant solution in the absence of oil). Furthermore, the increase in drug solubility observed in the microemulsion systems was not related to the solubility of the drug in the bulk oil. That is, while the smaller molecular volume oils, such as ethyl butyrate, exhibited a greater capacity for the drug, microemulsions containing these oils were only marginally better at solubilizing the drug than the corresponding micellar solution. In contrast, microemulsions containing the larger molecular volume oil, Miglyol 812, gave levels of drug solubilization almost three times those containing ethyl butyrate, yet the bulk capacity for drug in this oil was less than half that of ethyl butyrate. Light scattering and phase inversion temperature studies suggested that the structure of the microemulsion was sensitive to the oil being used, in that, at the low oil concentrations used in this study, the smaller molecular volume oils generally penetrated the interfacial surfactant monolayer in much the same way as a cosurfactant, causing an alteration, presumably a dilution, of the relatively concentrated polyoxyethylene region close to the hydrophobic core, thereby destroying one of the main loci of drug solubilization and counteracting any advantages encountered due to the high solubility of the drug in the bulk oil.

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Section: Methodssupporting

confidence: 52%

Section: Resultsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Effect of Oil on the Level of Solubilization of Testosterone Propionate into Nonionic Oil-in-Water Microemulsions

Malcolmson¹,

Satra²,

Kantaria³

et al. 1998

Journal of Pharmaceutical Sciences

154

View full text Add to dashboard Cite

show abstract

“…The last part of the evaporation path has been drawn as a straight line. Caution should be exercised when applying such schematic curves; earlier publications have demonstrated pronounced deviations from straight-line evaporation paths [13,14]. It should be noted that this caution is necessary only for the very last water contents; earlier parts of the evaporation, with water contents in excess of 18%, showed phase changes in agreement with a straight-line evaporation path.…”

Section: Discussionmentioning

confidence: 99%

Vapour pressure of a fragrance ingredient during evaporation in a simple emulsion

Friberg

Szymula

FEI

et al. 1997

Intern J of Cosmetic Sci

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The phase diagram water, phenethyl alcohol and laureth 4 was determined and the variation of the vapour pressure of the alcohol was determined during evaporation using gas chromatographic head-space analysis. The phase changes during evaporation were estimated from the phase diagram and compared to the appearance of the emulsion using optical microscopy. The transfer of the fragrance ingredient between different phases during the process was estimated and its measured vapour pressures compared to those calculated from values of earlier determination in different phases in the system. The agreement was good.

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“…[13,18,22 -25] Microemulsions are fundamentally different from emulsions, and their evaporation patterns have also attracted attention. The early contributions by Friberg's group [26,27] demonstrated the difference in the evaporation trajectory from a true emulsion, while the later contributions from the York group [28,29] have been of a more fundamental nature.…”

Section: Introductionmentioning

confidence: 98%

Evaporation from a Fragrance Emulsion

Friberg

2006

Journal of Dispersion Science and Technology

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The evaporation paths and the variation in vapor pressure during evaporation of limonene from a two-phase emulsion stabilized by a nonionic surfactant were calculated from published phase diagram and vapor pressures. The composition of the vapor was calculated from vapor pressures, and the evaporated vapor was assumed to be close to equilibrium composition. The calculations were made for relative humidities of 0 and 50%. The results showed the variation of the composition of the total emulsion as well as of its two phases as a function of the evaporation path. Furthermore, the weight of the total emulsion, of its two phases, and the remaining weights of water and limonene during evaporation were followed. Finally, the relation between the vapor pressure of limonene and the evaporation path was established. The change in the evaporation rate of water due to the modification of the relative humidity gave rise to a small, but significant, modification of the evaporation rate of the limonene. The influence is indirect, due to the dependence of its vapor pressure on the total composition of the emulsion. A combination of detailed information on the static emulsion features and the vapor pressure enabled an approximate estimation of the time dependence of the evaporation.

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Evaporation from microemulsions

Cited by 19 publications

References 16 publications

Effect of Oil on the Level of Solubilization of Testosterone Propionate into Nonionic Oil-in-Water Microemulsions

Effect of Oil on the Level of Solubilization of Testosterone Propionate into Nonionic Oil-in-Water Microemulsions

Vapour pressure of a fragrance ingredient during evaporation in a simple emulsion

Evaporation from a Fragrance Emulsion

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