Cloud point of mixed ionic-nonionic surfactant solutions in the presence of electrolytes

Marszall, Leszek

doi:10.1021/la00079a014

Cited by 86 publications

(30 citation statements)

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“…Although the change in phase separation upon addition of a second surfactant to one exhibiting a cloud point has been studied for some time (4,185,186), it wasn't until recently that a quantitative theories for liquid-liquid separation in surfactant mixtures have been proposed (118,187). Here, modeling efforts for binary mixtures built upon earlier work to understand phase separtion in single component nonionic systems such as alkyl-ethoxylates, alkyl glucosides and an alkyl gylcerol ether (188)(189).…”

Section: Precipitation Temperatures In Surfactant Mixtures When a Sumentioning

confidence: 99%

Mixed Surfactant Systems

Holland¹,

Rubingh

1992

Mixed Surfactant Systems

251

329

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The properties and behavior of mixed surfactant systems are discussed in the context of experimental techniques and modeling. The overview begins with a general description of mixed surfactant solutions, followed by a more detailed examination of mixed micelles, surfactant mixtures at interfaces, and the phase behavior of mixed systems. Topics include experimental measurements, approaches to modeling, nonideality, unusual surfactant types, micellar demixing, adsorption at various interfaces, chemical reactions in micelles, precipitation, cloud point phenomena and perspectives on the direction of future research on mixed surfactant systems.Mixed surfactant systems are encountered in nearly all practical applications of surfactants. These mixtures arise from several sources. First is the natural polydispersity of commercial surfactants which results from impurities in starting materials and variability in reaction products during their manufacture. These are less expensive to produce than isomerically pure surfactants and often provide better performance. Second is the deliberate formulation of mixtures of different surfactant types to exploit synergistic behavior in mixed systems or to provide qualitatively different types of performance in a single formulation (e.g. cleaning plus fabric softening). Finally, practical formulations often require the addition of surfactant additives to help control the physical properties of the product or improve its stability.

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Section: Precipitation Temperatures In Surfactant Mixtures When a Sumentioning

confidence: 99%

Mixed Surfactant Systems

Holland¹,

Rubingh

1992

Mixed Surfactant Systems

251

329

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“…The addition of less than 5% anionic to nonionic surfactant can reduce the amount of surfactant needed to solubilize equal amounts of oil and water by a factor of four. Phenomenologically, these observations are rationalized in terms of the hydrophilic-lipophilic balance (HLB) of the surfactant mixture (4,8,9), or the relative location of the surfactant-water critical point (10)(11)(12)(13)(14). Many of the structural aspects of anionic-nonionic surfactant mixtures have been observed in droplet and lamellar phases, including changes in phase progression (15,16), droplet size, and lamellar spacing (17,18).…”

Section: Introductionmentioning

confidence: 99%

The Phase Behavior and Microstructure of Efficient Cationic–Nonionic Microemulsions

Silas

Kaler

2001

Journal of Colloid and Interface Science

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“…Initially this clouding was ascribed to an increase in size and aggregation number, n s (10), of the micelles and to the formation of giant micelles, which were believed eventually to become insoluble in water (11). Later, it was realized that the clouding results from the clustering of micelles as a result of attractive intermicellar interactions, and the term "coacervate curve" was coined for concentrated micellar solutions with a conjectured liquid-like packing of the micelles (12,13). In the last two decades considerable attention has been paid to scattering behavior (14)(15)(16)(17) close to the critical point of these solutions.…”

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confidence: 99%

Small‐angle neutron scattering studies on sodium dodecylbenzenesulfonate‐tetra‐n‐butylammonium bromide systems

Kumar

Sharma

et al. 2006

J Surfact & Detergents

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A phase study was completed on aqueous sodium dodecylbenzenesulfonate (SDBS) and tetra-n-butylammonium bromide (Bu 4 NBr) systems, and consolute boundaries were drawn through cloud points. Samples were selected from both miscibility regions [under the lower consolute boundary (LCB) and above the upper consolute boundary (UCB)] for small-angle neutron scattering (SANS) studies. In the first set of experiments, the effect of varying Bu 4 NBr concentration on micellar parameters of 100 mM SDBS was studied at 30°C. The pure SDBS micelle has an aggregation number (n s ) of 51, and the effective charge on the monomer (α) is 0.17. With the addition of Bu 4 NBr, the n s of SDBS micelles increases while α decreases. The system with [Bu 4 NBr] = 39.5 mM (an above-UCB sample) showed clouding near room temperature (≈29°C) and had a high n s value (300) and a low α (= 0.09). The data indicated that the micelles lose ionic character in the presence of Bu 4 NBr. The temperature effect on this sample shows that α remains almost constant, while n s decreases on heating. A similar effect was observed with samples of lower Bu 4 NBr concentration (32 or 25 mM) in the presence of 100 mM SDBS. The same type of temperature effect was seen on a sample of under-LCB region (50 mM SDBS + 32 mM Bu 4 NBr); the n s values increased significantly as the LCB was approached. The overall SANS observations suggest that the micelles have low ionic character together with high n s values (a case of micellar growth) near LCB/UCB. Paper no. S1505 in JSD 9, 77-82 (Qtr. 1, 2006). KEY WORDS:Cloud point, consolute boundaries, smallangle neutron scattering, sodium dodecylbenzenesulfonate, tetra-n-butylammonium bromide.The observation of partial miscibility in binary surfactant/water micellar solutions is commonplace (1-5). Reports of both lower and upper consolute curves for nonionic and zwitterionic surfactants are frequent (1,2). There even exist a few reports of lower consolute curves for ionic surfactants in water (3,6-8).The phase boundary curve of the miscibility gap is commonly known as the "cloud" or "consolute" curve (9) in view of the pronounced turbidity of the solutions close to the phase separation. Initially this clouding was ascribed to an increase in size and aggregation number, n s (10), of the micelles and to the formation of giant micelles, which were believed eventually to become insoluble in water (11). Later, it was realized that the clouding results from the clustering of micelles as a result of attractive intermicellar interactions, and the term "coacervate curve" was coined for concentrated micellar solutions with a conjectured liquid-like packing of the micelles (12,13). In the last two decades considerable attention has been paid to scattering behavior (14-17) close to the critical point of these solutions. Hayter et al. (15) concluded from small-angle neutron scattering (SANS) experiments that the observed increase in the forward scattering is due to the formation of larger particles consisting of spherical micelles of fixed siz...

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Cloud point of mixed ionic-nonionic surfactant solutions in the presence of electrolytes

Cited by 86 publications

References 1 publication

Mixed Surfactant Systems

Mixed Surfactant Systems

The Phase Behavior and Microstructure of Efficient Cationic–Nonionic Microemulsions

Small‐angle neutron scattering studies on sodium dodecylbenzenesulfonate‐tetra‐n‐butylammonium bromide systems

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