Quantitative determination of a sodium dodecyl sulfate micellar radius through positron annihilation lifetime spectroscopy

Bockstahl, Frédéric; Duplâtre, G.

doi:10.1039/a901518c

Cited by 23 publications

(62 citation statements)

References 19 publications

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“…1,30 For prolate ellipsoids, N ag can be calculated from the following expression 13 where a and b are the semimajor and semiminor axes of the ellipsoid, respectively, and N ag 0 is the aggregation number for spherical micelles of radius b. The latter was estimated from the length of the stretched SDS molecule at 298 K, as (units of nm) 31 Some slight variation with T was allowed for b, to the extent of the cubic root of the variation of the SDS molecule volume from a given T to another; in this way, N ag 0 is T independent (see eq 22).…”

Section: Resultsmentioning

confidence: 97%

“…For the sake of space, the final equation is not given but can be deduced from the treatments developed in our previous work. 1,2 The Ps radius, R Ps in eq 6, was calculated on the basis of one of the simplest bubble models: 15 in the T range explored, R Ps varies very smoothly, from 0.312 to 0.315 nm between 305 and 343 K, respectively; it was verified that moderate changes in these values would not affect significantly the results to come. The viscosity of the (SDS + NaCl) solutions, η in eq 6, was calculated from the viscosity of pure water, η w , at each T, and the NaCl concentration, C NaCl , according to 16…”

Section: P(n Q ) Is Ruled By the Poisson Distribution Asmentioning

confidence: 99%

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Micellar Radii and High Aggregation Numbers in a 0.6 M NaCl Sodium Dodecylsulfate Solution Determined through Positron Annihilation Lifetime Spectroscopy

and¹,

Duplâtre²,

and³

et al. 2004

J. Phys. Chem. B

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The equations related to a recently published method to measure both the micellar average radius (R_{mic}) and aggregation number (N_{ag}) using a single technique, positron annihilation lifetime spectroscopy (PALS), are extended and applied to a 0.25 M sodium dodecylsulfate (SDS) aqueous solution in the presence of large amounts of NaCl (0.6 M) as a function of temperature (T). The analysis of the PALS spectra confirms that the triplet state of positronium, o-Ps, originally formed in the aqueous subphase (o-Ps^{aq}) becomes trapped inside the organic core of the micelles (o-Ps^{org}). The equations take into account the variety of o-Ps^{org} lifetimes promoted when introducing a Ps oxidizer (duroquinone) into the solution, which distributes into the micelles according to Poisson's law. The variation with T of R_{mic} derived from PALS agrees well with two sets of values previously published, showing an important decrease upon heating, from about 5.8 nm at 305 K down to 2.3 nm at 343 K. By contrast, although all three sets of data agree on the concomitant decrease in N_{ag} with T, toward values denoting a nearly spherical shape of the micelles at high T, large differences are found at the lowest T studied, the PALS data giving much higher values than those previously published. However, our data show good agreement with the variation of N_{ag} with T, calculated from the measured R_{mic} and the volume of the SDS molecules on the assumption that the micelles display a prolate ellipsoid shape

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Section: Resultsmentioning

confidence: 97%

Section: P(n Q ) Is Ruled By the Poisson Distribution Asmentioning

confidence: 99%

Micellar Radii and High Aggregation Numbers in a 0.6 M NaCl Sodium Dodecylsulfate Solution Determined through Positron Annihilation Lifetime Spectroscopy

and¹,

Duplâtre²,

and³

et al. 2004

J. Phys. Chem. B

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“…The first system chosen was such that the micelles had been well characterised previously, through conventional techniques (such as light or neutron scattering), in order to establish a general method in PALS. Thus, for sodium dodecylsulphate (SDS), the 4 combinations, C1 through C4, were used when fitting the spectra [5]. The results are shown in Table V.…”

Section: The Case Of Large Solutes: Micelles In Watermentioning

confidence: 94%

“…For instance, in the case of Ps trapping in micelles, the product of the reaction is the trapped o-Ps, which possesses a longer lifetime than it has in water; the corresponding mathematical expression for the o-Ps decay, F (t), reads as follows [5]: Assessing the effect of TD for the solutes listed in Table I cannot be made from experimental data as the PALS spectra are no more available. Therefore, the spectra were calculated from published PALS parameters, and the long-lived part (o-Ps decay) was fitted to the relevant o-Ps decay equation, including k(t).…”

Section: Effect Of Td On the Reaction Rate Coefficientmentioning

confidence: 99%

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Current Problems and Unknowns in Positronium Dynamics

Duplâtre

2008

Acta Phys. Pol. A

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A survey is made on positronium dynamics in liquids. From literature data, it is shown that applying conventional kinetics to positronium reactions leads to quite satisfactory results in a large variety of solvents, solutes, reaction types and temperatures. On the opposite, applying the theoretically well established concepts of positronium bubble state and time-dependent reaction rate coefficient would imply the use of unrealistic solute radii in the related kinetic equations, with possible exception of large solutes (micelles). Some solutes displaying unexpectedly high reaction rate constants are shown to be refractory to any of the above quantitative approaches. The particular case of reversible positronium bound-state formation is further examined, the most consistent results arising, again, from the conventional analysis of the data.

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Ein Porphyrinfarbstoff mit monoexponentiellem Intensitäts‐ und Anisotropieabklingverhalten in sphärischen Micellen

2004

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Die Größe einer Micelle wird üblicherweise durch Streuungstechniken wie Neutronen-und Röntgenstreuung bestimmt. [1] Prinzipiell können Fluoreszenzmessungen die gleichen Informationen liefern, allerdings mangelte es bislang an geeigneten Farbstoffen. Als Chromophore zur Untersuchung von Micellengrößen wurden bislang Acridinorange, [2] Rhodamin B, Octadecylrhodamin B, [3] mehrere Porphyrine, [4] Merocyanin 540, [5] Nilrot, Cresylviolett und ein Cyaninfarbstoff (DODCl) eingesetzt.[

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Quantitative determination of a sodium dodecyl sulfate micellar radius through positron annihilation lifetime spectroscopy

Cited by 23 publications

References 19 publications

Micellar Radii and High Aggregation Numbers in a 0.6 M NaCl Sodium Dodecylsulfate Solution Determined through Positron Annihilation Lifetime Spectroscopy

Micellar Radii and High Aggregation Numbers in a 0.6 M NaCl Sodium Dodecylsulfate Solution Determined through Positron Annihilation Lifetime Spectroscopy

Current Problems and Unknowns in Positronium Dynamics

Ein Porphyrinfarbstoff mit monoexponentiellem Intensitäts‐ und Anisotropieabklingverhalten in sphärischen Micellen

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