Interfacial tension minima in oil–water–surfactant systems. Systems containing pure non-ionic surfactants, alkanes and inorganic salts

Aveyard, Robert; Lawless, T.A.

doi:10.1039/f19868202951

Cited by 39 publications

(16 citation statements)

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“…The cloud-point temperature (T cp ) of various nonionic surfactants (most frequently at ca. 1 to 2 wt% surfactant) has consequently been carefully determined for aqueous solutions of a wide variety of electrolytes and explanations have been given of the observed trends [8,[11][12][13][14][15][16][17][18][19][20][21]. In the present study, the distinguishing feature is that practically the complete lcb of the surfactant C 8 E 5 was determined in the presence of, respectively, NaF, LiCl, NaCl, NaBr and NaI in the solution, at several molalities, so that also high values were attained (up to 5.0 m of the ionic species).…”

Section: Introductionmentioning

confidence: 99%

Lower consolute boundaries of the nonionic surfactant C8E5 in aqueous alkali halide solutions: An approach to reproduce the effects of alkali halides on the cloud-point temperature

Weckström

Papageorgiou

2007

Journal of Colloid and Interface Science

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Section: Introductionmentioning

confidence: 99%

Lower consolute boundaries of the nonionic surfactant C8E5 in aqueous alkali halide solutions: An approach to reproduce the effects of alkali halides on the cloud-point temperature

Weckström

Papageorgiou

2007

Journal of Colloid and Interface Science

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“…On the basis of previous work on model systems [22,23], this finding is unsurprising, since at this point the system is close to an optimum condition, as mentioned in the introduction. It is found that the interfacial tensions for the ethoxylated nonylphenol surfactants begin to decrease some 20-40 K below the respective cloud points, which attain minimum values before showing signs of increasing at higher temperatures.…”

Section: Discussionmentioning

confidence: 83%

“…When R = 1, planar monolayers will result, leading to a minimum interfacial tension where there is no net curvature. Temperature scans characteristically produce -V-shaped‖ interfacial tension behaviour reaching values as low as 10 -3 mN m -1 [23].…”

Section: Discussionmentioning

confidence: 99%

“…By analogy with results from studies involving pure oils and surfactants [22,23], oil/water interfacial tension is a key indicator of the state of the system in terms of stability and the preferred location of the surfactant, consistent with thermodynamic considerations [23]. For compositionally complex bitumens, however, predicting specific effects will be more challenging, a situation made even more difficult using polydisperse surfactants [24], making a more empirical approach necessary.…”

Section: Bitumen/water Interfacial Tension Studiesmentioning

confidence: 99%

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Thermal destabilisation of bitumen-in-water emulsions – A spinning drop tensiometry study

Taylor

2011

Fuel

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“…For example it was observed that larger molecular volume oils tend to have a higher T Cloud compared to smaller volume oils for o/w microemulsions. 38) Smaller molecular oils may penetrate into the interface behaving as cosurfactant and thus resulting in a more asymmetrical structure with lower T Cloud . Although this explanation was applied to o/w systems, the results of the current investigation shows that w/o Cremophor EL microemulsions containing the lower molecular volume oil (IPM) have also a lower T Cloud .…”

Section: )mentioning

confidence: 99%

Formulation and Physicochemical Characterization of Imwitor 308 Based Self Microemulsifying Drug Delivery Systems

Zargar‐Shoshtari

Wen

Alany

2010

CHEMICAL & PHARMACEUTICAL BULLETIN

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Microemulsions are thermodynamically stable, transparent, isotropic systems, consisting of oil, water and surfactant with or without a cosurfactant. They are considered ideal for drug delivery due to their low viscosity, ease of preparation, improved drug stability and solubility, small droplet size, surfactant provoked permeability and protection against enzymatic degradation.1) The later characteristics are responsible for improved permeability of the drug across biological membranes including the skin. Although the oil and surfactant constituents are known to enhance the solubility of lipophilic drugs, at higher weight fraction of water (j), their solubility may be greatly compromised. To overcome this effect microemulsions containing cyclodexterine have been investigated. Incorporation of cyclodexterines has been shown to improve the solubility of the model steroid drug progesterone in selected microemulsions by 3300 folds.2) Self Microemulsifying Drug Delivery Systems (SMEDDS) can be considered a novel alternative to conventional transdermal delivery systems.3) SMEDDS are preconcentrated (waterfree) microemulsions, made up of oils and surfactants. Upon dilution with an aqueous medium and gentle agitation, these systems can form microemulsions. 4) Enhanced solubility and improved bioavailability are amongst the main advantages of SMEDDS.Before SMEDDS can be used as drug delivery systems it is necessary to characterize the internal structure of the resulting microemulsion. This is highly critical as multiple colloidal and coarse dispersions may coexist. Amongst these are microemulsions, coarse emulsions, various liquid crystalline systems (hexagonal, reverse hexagonal, lamellar, cubic) and gels. These can form upon mixing oils, surfactants and water. Moreover microemulsions are known to have different microstructures namely oil in water (o/w), water in oil (w/o) and bicontinuous. 5) Elucidating the internal structure of microemulsions is of a great interest as the phase behaviour of these systems can influence drug solubility, stability and in vitro release. Phase behaviour of microemulsions can be monitored through visual inspection, measuring electrical conductivity, viscosity, droplets size, density determination, surface tension measurements, and diffusion coefficient measurements. Visual observation is one of the first and foremost techniques used to establish the phase boundaries and distinguish microemulsions from coarse emulsions, liquid crystals and gels. To further differentiate microemulsions form lamellar liquid crystals one can take advantage of other experimental techniques such as polarized light microscopy and viscosity measurements. In general microemulsions display Newtonian flow with low viscosity whilst liquid crystals exhibit non-Newtonian flow and are of relatively high viscosity.5) Furthermore viscosity can also be used to study the microstructure of microemulsions. [6][7][8] Normally o/w microemulsions have a lower viscosity compared to w/o microemulsions in which the more viscous oil ...

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Interfacial tension minima in oil–water–surfactant systems. Systems containing pure non-ionic surfactants, alkanes and inorganic salts

Cited by 39 publications

References 0 publications

Lower consolute boundaries of the nonionic surfactant C8E5 in aqueous alkali halide solutions: An approach to reproduce the effects of alkali halides on the cloud-point temperature

Lower consolute boundaries of the nonionic surfactant C8E5 in aqueous alkali halide solutions: An approach to reproduce the effects of alkali halides on the cloud-point temperature

Thermal destabilisation of bitumen-in-water emulsions – A spinning drop tensiometry study

Formulation and Physicochemical Characterization of Imwitor 308 Based Self Microemulsifying Drug Delivery Systems

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