The Phase Rule Behavior of Concentrated Aqueous Systems of a Typical Colloidal Electrolyte: Sodium Oleate.

Vold, Robert D.

doi:10.1021/j150396a013

Cited by 40 publications

(36 citation statements)

References 12 publications

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“…The Krafft discontinuity is slightly changed with increasing the surfactant composition. This result is in agreement with studies by Vold [10], where this discontinuity was identified as the temperature at which the last trace of opaque solid disappears by heating.…”

Section: Phase Diagramsupporting

confidence: 93%

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Shear rheology and phase behaviour of sodium oleate/water mixtures

Antunes

Coppola

Gaudio

et al. 2007

Colloids and Surfaces A: Physicochemical and Engineering Aspect

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The knowledge of structural and dynamical properties in binary sodium oleate (NaO)/water mixtures represents a first step for studying new biocompatible structures. In addition, a deeper understanding of their flow behaviour is crucial to control their mechanical properties. The purpose of this investigation was to revisit the binary NaO/water phase diagram through a combined effort of shear-rheology, NMR-diffusometry, optical polarizing microscopy and differential scanning calorimetry. The preparation of NaO/water mixtures in this work fitted with the interesting regions of the phase diagrams where most of the new systems will be prepared (i.e. from 0.01 to 30 wt.% NaO and within the temperature range 5-70 • C).Steady shear and linear viscoelastic experiments were accurately performed and the relationship between phase morphology and rheological properties was also studied. Regarding the mixtures at low surfactant concentrations, the shear flow showed: (1) a structural evolution into the liquid micellar phase (L 1 ) as a function of composition and (2) the presence of a viscous micellar region (L * 1 ) induced by temperature and composition changes. NaO/water mixtures with a liquid-crystalline structure (hexagonal H 1 ) were studied by linear shear deformations and paying particular attention to frequency and temperature scans. Viscoelastic spectra of H 1 phase presented a gel-like response which, although not expected, indicated the presence of a stiff liquid-crystalline lattice. Finally, a correlation between rheology and microstructural changes was conducted by the "weak-gel" model.

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Section: Phase Diagramsupporting

confidence: 93%

“…The phase diagram of NaO in water was the subject of two dated studies by Vold [10] and Luzzati et al [11], respectively. They study the presence of an isotropic liquid region and an hexagonal liquid crystalline phase, lying within an accessible experimental temperature-composition interval.…”

Section: Introductionmentioning

confidence: 99%

Shear rheology and phase behaviour of sodium oleate/water mixtures

Antunes

Coppola

Gaudio

et al. 2007

Colloids and Surfaces A: Physicochemical and Engineering Aspect

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“…While the sample containing only NaO is transparent, which results from the micellar phase reported in the literature [18,19], the remaining samples exhibit bluish color, which is usually related to the existence of vesicles.…”

Section: Methodsmentioning

confidence: 89%

“…These 2 amphiphilic molecules form different structures in water. While the critical packing parameter (CPP) of MO exceeds one, NaO forms normal micelles [18,19]. In the dilute corner, spontaneously formed vesicles with long-term stability are found (for at least 1 year) [15].…”

Section: Introductionmentioning

confidence: 99%

Gelation of charged bio-nanocompartments induced by associative and non-associative polysaccharides

Antunes

Coppola

Rossi

et al. 2008

Colloids and Surfaces B: Biointerfaces

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a b s t r a c tVesicles composed of sodium oleate (NaO) and monoolein (MO) are adequate candidates for drug nanoencapsulation and controlled release due to their stability and perceived biocompatibility. The object of the present study is to design hydrogels based on those anionic vesicles and polymers of both non-associative and associative type. The selected macromolecules were k-carrageenan (KC), carboxymethyl cellulose (CMC) and hydrophobically modified carboxymethyl cellulose (HMCMC). While the polymer-vesicle association was probed by rheology, the influence of the polymer on the vesicle stability was monitored by cryo-TEM and calorimetric measurements.The effects of the polymer on the rheological properties of surfactant aggregate solutions clearly depend on the polymer type: the storage moduli of the polymer-vesicle mixtures, compared to the vesicles alone, increases around 2 orders of magnitude if the polymer is non-associative and 4 orders of magnitude if the macromolecule is of associative type.As the vesicles are added, the non-associative polymer networks tend to be disrupted, while the networks formed by associative polymer get more robust. These observations can be explained by fundamental changes in electrostatic/hydrophobic interactions: vesicles entrapped in KC networks convert the polysaccharide in a highly charged entity and favor high electrostatic repulsions between the chains; this encourages network collapse. The opposite picture is experienced in HMCMC systems, i.e., such network is stabilized by the presence of vesicles. This is ascribed to the enhanced hydrophobic association, compensating the electrostatic repulsions between vesicles and polymer chains.

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“…It is well known that the obvious influence of the existence of C=C bond in sodium oleate (NaO) on the mixture properties of cationic surfactants and NaO is different from the influences of cationic surfactants and NaS [12,13] . The phase boundaries in ternary systems of NaO, compared with other soap, were reported as early as in 1939 [14,15] . However, the comparative study on the salt-free cationic surfactants mixed with alkyl fatty acids with a double carbon bond (C=C) and the saturation hydrophobic alkyl chain has not been reported in literature [9] .…”

Section: Cationic Base Surfactant Tetradecyltrimethylammonium Hydroxmentioning

confidence: 99%

Phase behavior and properties of salt-free cationic/anionic surfactant mixtures of oleic acid and stearic acid

Zhao

Song

et al. 2009

Chin. Sci. Bull.

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The Phase Rule Behavior of Concentrated Aqueous Systems of a Typical Colloidal Electrolyte: Sodium Oleate.

Cited by 40 publications

References 12 publications

Shear rheology and phase behaviour of sodium oleate/water mixtures

Shear rheology and phase behaviour of sodium oleate/water mixtures

Gelation of charged bio-nanocompartments induced by associative and non-associative polysaccharides

Phase behavior and properties of salt-free cationic/anionic surfactant mixtures of oleic acid and stearic acid

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