Volumes, Heat Capacities, and Conductivities of Water-Surfactant-18-Crown-6 Ether Systems

Bakshi, Mandeep Singh; Crisantino, R.; Lisi, R. De; Milioto, Stefana

doi:10.1021/la00014a016

Cited by 25 publications

(30 citation statements)

References 1 publication

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“…The cmc values for both the binary mixtures are significantly higher in the presence of CD than those in pure water, and the values increase with the increase in the amount of CD. Similar results for single cationic surfactants in the presence of CD have already been observed and discussed in much detail (7)(8)(9)(10). Therefore, it can be said that this general behavior for the single ionic surfactants in the presence of CD can also be extended to the binary cationic mixed surfactants.…”

Section: Critical Micelle Concentration In Pure Water and CD + Water supporting

confidence: 84%

“…The degree of micelle ionization has been calculated by the method suggested by Evans (20) based upon Stokes' law for the mobility of the micelles, and the micelles are considered to be spherical in shape. It is given by χ = (n − m)/n, [7] where n is the micelle aggregation number and m is the number of micelle-bound counterions. The n and m are related through the relation…”

Section: Degree Of Micelle Ionizationmentioning

confidence: 99%

“…The most significant property of CD is to form strong inclusion complexes with the hydrophobic tail of amphiphilic molecules such as surface-active agents (2)(3)(4)(5)(6) and to impart significant influence on the micellar properties of surfactants (2)(3)(4)(5)(6)(7)(8)(9)(10)(11). A lot of work has been done to study the inclusion complex formation between a variety of single ionic surfactants and the CD cavity (2)(3)(4)(5)(6).…”

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Cationic Mixed Micelles in the Presence of β-Cyclodextrin: A Host–Guest Study

Bakshi

2000

Journal of Colloid and Interface Science

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Section: Critical Micelle Concentration In Pure Water and CD + Water supporting

confidence: 84%

Section: Degree Of Micelle Ionizationmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Cationic Mixed Micelles in the Presence of β-Cyclodextrin: A Host–Guest Study

Bakshi

2000

Journal of Colloid and Interface Science

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“…It is clear from the figure that salts (0.05 M) cause well-defined maxima at lower NaSal concentrations, indicating increased association in NaSal caused by the presence of salts. A similar effect of salts in decreasing the CMC of ionic surfactants is well documented in the literature (31)(32)(33). The increased association of NaSal in the presence of salts may thus be due to the screening action of salts (counter ions), which lowers the repulsive forces between the polar head groups.…”

Section: Resultssupporting

confidence: 70%

Additive‐induced association in unconventional systems: A case of the hydrotrope

Kumar

Parveen

Kabir-ud-Din

2005

J Surfact & Detergents

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It is well known that hydrotropes have a very high minimum hydrotrope concentration (MHC), posing a question on their applications. We have found that MHC (obtained by conductivity and surface tension measurements) can be reduced by the addition of foreign materials. The association tendency can be improved by the addition of salts, n-alkanols, and ureas. Urea decreases or increases the MHC depending on whether the urea content is lower or higher (e.g., the increased solubility of sparingly soluble riboflavin corroborates the increase in the hydrotropic properties of the system). In the present work, the association tendencies of sodium salicylate (a well-known hydrotrope), sodium dodecyl sulfate, and sodium bromide were compared. The results have direct implications in the mechanism of protein denaturation and may provide insight into the role of urea in supramolecular assemblies.The word hydrotropy was first used by Neuberg (1). This term is used to describe the phenomenon of increasing aqueous solubility of otherwise sparingly soluble organic compounds in solutions of certain organic salts (2). These salts, called hydrotropes, include sodium, potassium, calcium, and ammonium salts of aromatic acids or phenols. McKee (3) concluded that a rather high content of hydrotrope in water is required for its action to be displayed and that the phenomenon is similar to the salting-in process. Booth and Everson (4) showed that the solubility increase does not occur monotonically with hydrotrope concentration, but displays a sigmoidal character. Furthermore, hydrotrope aggregation is responsible for the increase in aqueous solubility that occurs beyond a certain hydrotrope concentration termed the minimum hydrotrope concentration (MHC), analogous to the critical micelle concentration (CMC) for a surfactant (5). Reviews are now available detailing the progress in hydrotrope research (6-11).The aqueous solubility of surfactants is limited by the formation of a liquid crystalline phase, which can be destabilized in the presence of a typical hydrotrope. The enhanced disorder resulting from the residence of the hydrotrope in the association structure of the condensed phase brings about morphological changes from liquid crystal to oil-in-water and bicontinuous regions (11,12). Guo et al. (11) observed that the addition of vitamin C (a hydrotrope) to a cetyltrimethylammonium bromide/1-pentanol/p-xylene/water system caused the area of micellar and inverse micellar regions to increase and ultimately coalesce, whereas the liquid crystalline region shrank.Many attempts have been made to compare hydrotropes with conventional surfactants over the past 45 years (13-16). Danielsson and Stenius (17) observed the aggregation behavior of sodium carboxylates and reported that octanoate and higher members form micelles whereas lower ones form hydrotropes. Firman et al. (18) concluded that a clear distinction between a simple hydrotropic salt and a conventional surfactant is difficult to make. In most cases, hydrotropes have a strong ionic g...

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“…Of particular interests to SDS MEKC are the formation of an 18C6–Na + complex and the effect of this complexation on the SDS PSP. 18C6 and Na + form a 1:1 complex that is stable as a result of strong ion–dipole interactions ( K stab =6.6 M −1 at 25°C) 11–16. When introduced to an aqueous solution of SDS, 18C6 sequesters Na + , leading to an increase in $SO_{4}^{ - }$ head group repulsion.…”

mentioning

confidence: 99%