Titration calorimetric and spectrophotometric studies of micelle formation by alkyltrimethylammonium bromide in aqueous solution

Bach, J.; Blandamer, M. J.; Bijma, Koos; Engberts, Jbfn; Kooreman, Peter; Kacperska, Anna; Rao, K. Chowdoji; Subha, M. C. S.

doi:10.1039/ft9959101229

Cited by 38 publications

(28 citation statements)

References 19 publications

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“…The enthalpy data from the micelle system did not reflect an additional contribution from demicellization as HDTMA sorbed below the ECEC. The enthalpy of micellization, about Ϫ9.7 kJ/mol (31)(32)(33), is close to the measured enthalpies of sorption. This suggests that the dominant enthalpic effect is the transfer of HDTMA from the water phase to the bound phase, regardless of the HDTMA structure on the surface or in solution.…”

Section: Enthalpy Of Sorptionsupporting

confidence: 67%

“…For the 15 CH 2 -CH 2 bonds in the HDTMA molecule, the predicted transfer energy is then between 25.5 and 42 kJ/mol. A total value for micellization of HDTMA also can be calculated or measured to be about Ϫ32 kJ/mol (18,(31)(32)(33). The ⌬G spec values for sorption above the ECEC (obtained using TEA as a measure of ⌬G elec ) are Ϫ18.3 and Ϫ25.5 kJ/mol, respectively, for the monomeric and micellar HDTMA systems.…”

Section: Free Energy Of Sorptionmentioning

confidence: 99%

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Thermodynamics of Cationic Surfactant Sorption onto Natural Clinoptilolite

Sullivan

Carey

Bowman

1998

Journal of Colloid and Interface Science

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Section: Enthalpy Of Sorptionsupporting

confidence: 67%

Section: Free Energy Of Sorptionmentioning

confidence: 99%

Thermodynamics of Cationic Surfactant Sorption onto Natural Clinoptilolite

Sullivan

Carey

Bowman

1998

Journal of Colloid and Interface Science

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“…Over the next series of injections the calorimeter monitors the effect of dilution of the micellar solution in the syringe. For hexadecyltrimethylammonium bromide (CTAB), the two regimes, deaggregation of micelles and dilution of micellar solution, are clearly identified [3] leading to estimates of the cmc and AmjJf, 0.95• -3 mol dm -3 and -10.3 kJ mol -l. Addition of NaBr(aq) up to 0.02 mol dm 3, of NaCl(aq) up to 0.1 mol dm 3 and EtOH(aq) up to a mole fraction of 0.0469 lowers [4] the cmc of CTAB. Similarly, addition of n-pentanol up to 13.…”

Section: Introductionmentioning

confidence: 95%

“…A titration microcalorimeter [MicroCal Ltd., USA] was used as previously 6 3 described [3,5]. The volume of the sample cell was 1.4115• m and the volume of each injected aliquot was 5• -9 m 3.…”

Section: Calorimetermentioning

confidence: 99%

“…Titration microcalorimetry is an important technique in the characterisation of amphipathic salts in aqueous solutions [1][2][3]. In principle, two pieces of information emerge from one experiment (at fixed temperature and pressure); (i) the critical micellar concentration (cmc) and (ii) enthalpy of micelle formation which for very dilute solution is approximately the limiting enthalpy of micelle formation, Amid/~.…”

Section: Introductionmentioning

confidence: 99%

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Effects of added dotab on thecmc and enthalpy of micelle formation at 298.2 K for CTAB(aq)

Blandamer

Cullis

Soldi

et al. 1996

Journal of Thermal Analysis

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In a titration calorimetric study an aqueous solution held in a syringe and containing hexadeeyltrimethylammonium bromide (CTAB; 15.4x10 -3 tool dm -3) is injected in aliquots (5• 10 -3 dm 3) into a sample cell containing initially water. Analysis of the data shows that the cmc equals 0.97x10 -3 dm -3 and the enthalpy of micelle formation equals -10.3 kJ mol -l. When the solution in the syringe is replaced by a mixed surfaetant solution, CTAB+dodeeyltrimethylam-monium bromide, at the same total concentration of surfactant, the cmc of CTAB decreases gradually with increasing mole fraction of DOTAB but the enthalpy of CTAB mieelle formation is hardly affected. We conclude, therefore, that incorporation of DOTAB monomers into the CTAB micelles stabilizes entropieally the CTAB micelles.

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A Titration Microcalorimetric Study of the Effects of Halide Counterions on Vesicle-Forming Aggregation in Aqueous Solution of Branched-Chain Alkylpyridinium Surfactants

Gooijer

Engberts

Blandamer

2000

Journal of Colloid and Interface Science

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Take-down policy If you believe that this document breaches copyright please contact us providing details, and we will remove access to the work immediately and investigate your claim.Downloaded from the University of Groningen/UMCG research database (Pure): http://www.rug.nl/research/portal. For technical reasons the number of authors shown on this cover page is limited to 10 maximum. Titration microcalorimetry is used to study the influences of iodide, bromide, and chloride counterions on the aggregation of vesicle-forming 1-methyl-4-(2-pentylheptyl)pyridinium halide surfactants. Formation of vesicles by these surfactants was characterised using transmission electron microscopy. When the counterion is changed at 303 K through the series iodide, bromide, to chloride, the critical vesicular concentration (cvc) increases and the enthalpy of vesicle formation changes from exo-to endothermic. With increase in temperature to 333 K, vesicle formation becomes strongly exothermic. Increasing the temperature leads to a decrease in enthalpy and entropy of vesicle formation for all three surfactants. However the standard Gibbs energy for vesicle formation is, perhaps surprisingly, largely unaffected by an increase in temperature, as a consequence of a compensating change in both standard entropy and standard enthalpy of vesicle formation. Interestingly, standard isobaric heat capacities of vesicle formation are negative, large in magnitude but not strikingly dependent on the counterion. We conclude that the driving force for vesicle formation can be understood in terms of overlap of the thermally labile hydrophobic hydration shells of the alkyl chains.

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Titration calorimetric and spectrophotometric studies of micelle formation by alkyltrimethylammonium bromide in aqueous solution

Cited by 38 publications

References 19 publications

Thermodynamics of Cationic Surfactant Sorption onto Natural Clinoptilolite

Thermodynamics of Cationic Surfactant Sorption onto Natural Clinoptilolite

Effects of added dotab on thecmc and enthalpy of micelle formation at 298.2 K for CTAB(aq)

A Titration Microcalorimetric Study of the Effects of Halide Counterions on Vesicle-Forming Aggregation in Aqueous Solution of Branched-Chain Alkylpyridinium Surfactants

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