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Temperature Effect on the Nanostructure of SDS Micelles in Water.

Hammouda B - J Res Natl Inst Stand Technol (2013)

Bottom Line: Micelles were found to be slightly compressed (oblate ellipsoids) and their sizes shrink with increasing temperature.This fraction was found to be high (close to one) except for samples around 1 % SDS fraction.The micelle aggregation number was found to decrease with increasing temperature and/or decreasing SDS fraction.

View Article: PubMed Central - PubMed

Affiliation: National Institute of Standards and Technology, Gaithersburg, MD 20899.

ABSTRACT
Sodium dodecyl sulfate (SDS) surfactants form micelles when dissolved in water. These are formed of a hydrocarbon core and hydrophilic ionic surface. The small-angle neutron scattering (SANS) technique was used with deuterated water (D2O) in order to characterize the micelle structure. Micelles were found to be slightly compressed (oblate ellipsoids) and their sizes shrink with increasing temperature. Fits of SANS data to the Mean Spherical Approximation (MSA) model yielded a calculated micelle volume fraction which was lower than the SDS surfactant (sample mixing) volume fraction; this suggests that part of the SDS molecules do not participate in micelle formation and remain homogeneously mixed in the solvent. A set of material balance equations allowed the estimation of the SDS fraction in the micelles. This fraction was found to be high (close to one) except for samples around 1 % SDS fraction. The micelle aggregation number was found to decrease with increasing temperature and/or decreasing SDS fraction.

No MeSH data available.


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Variation of the micelle charge with increasing SDS mass fraction for various sample temperatures.
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f8-jres.118.008: Variation of the micelle charge with increasing SDS mass fraction for various sample temperatures.

Mentions: Fit results show that the charge on the micelles increases with SDS weight fraction (in Fig. 8) as it should since the size of micelles increases with increasing SDS fraction. Micelle charges, however, decrease with increasing temperature since the micelle volume decreases with increasing temperature. This trend breaks down for the highest SDS mass fraction (20 %) sample. The same saturation trend at high SDS fraction was observed previously [2]. Since the SDS molecule carries one electron charge on the ionized oxygen atom, the micelle charge scales with the micelle aggregation number.


Temperature Effect on the Nanostructure of SDS Micelles in Water.

Hammouda B - J Res Natl Inst Stand Technol (2013)

Variation of the micelle charge with increasing SDS mass fraction for various sample temperatures.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4487321&req=5

f8-jres.118.008: Variation of the micelle charge with increasing SDS mass fraction for various sample temperatures.
Mentions: Fit results show that the charge on the micelles increases with SDS weight fraction (in Fig. 8) as it should since the size of micelles increases with increasing SDS fraction. Micelle charges, however, decrease with increasing temperature since the micelle volume decreases with increasing temperature. This trend breaks down for the highest SDS mass fraction (20 %) sample. The same saturation trend at high SDS fraction was observed previously [2]. Since the SDS molecule carries one electron charge on the ionized oxygen atom, the micelle charge scales with the micelle aggregation number.

Bottom Line: Micelles were found to be slightly compressed (oblate ellipsoids) and their sizes shrink with increasing temperature.This fraction was found to be high (close to one) except for samples around 1 % SDS fraction.The micelle aggregation number was found to decrease with increasing temperature and/or decreasing SDS fraction.

View Article: PubMed Central - PubMed

Affiliation: National Institute of Standards and Technology, Gaithersburg, MD 20899.

ABSTRACT
Sodium dodecyl sulfate (SDS) surfactants form micelles when dissolved in water. These are formed of a hydrocarbon core and hydrophilic ionic surface. The small-angle neutron scattering (SANS) technique was used with deuterated water (D2O) in order to characterize the micelle structure. Micelles were found to be slightly compressed (oblate ellipsoids) and their sizes shrink with increasing temperature. Fits of SANS data to the Mean Spherical Approximation (MSA) model yielded a calculated micelle volume fraction which was lower than the SDS surfactant (sample mixing) volume fraction; this suggests that part of the SDS molecules do not participate in micelle formation and remain homogeneously mixed in the solvent. A set of material balance equations allowed the estimation of the SDS fraction in the micelles. This fraction was found to be high (close to one) except for samples around 1 % SDS fraction. The micelle aggregation number was found to decrease with increasing temperature and/or decreasing SDS fraction.

No MeSH data available.


Related in: MedlinePlus