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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.


Related in: MedlinePlus

Variation of the ellipsoid micelle volume with increasing temperature for the various SDS mass fractions.
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f7-jres.118.008: Variation of the ellipsoid micelle volume with increasing temperature for the various SDS mass fractions.

Mentions: The ellipsoidal micelle (oblate scattering particle) volume is estimated as VP = 4πRaRb2/3. This volume is seen (in Fig. 7) to decrease consistently with increasing temperature and to increase with increasing SDS mass fraction. As temperature increases, the micelle volume decreases (so does the aggregation number) thereby yielding more (smaller) micelles. This is likely due to many factors that include softening of hydrogen-bonding of water molecules to the surfactant headgroups and packing of the surfactant tails.


Temperature Effect on the Nanostructure of SDS Micelles in Water.

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

Variation of the ellipsoid micelle volume with increasing temperature for the various SDS mass fractions.
© Copyright Policy - open-access
Related In: Results  -  Collection

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

f7-jres.118.008: Variation of the ellipsoid micelle volume with increasing temperature for the various SDS mass fractions.
Mentions: The ellipsoidal micelle (oblate scattering particle) volume is estimated as VP = 4πRaRb2/3. This volume is seen (in Fig. 7) to decrease consistently with increasing temperature and to increase with increasing SDS mass fraction. As temperature increases, the micelle volume decreases (so does the aggregation number) thereby yielding more (smaller) micelles. This is likely due to many factors that include softening of hydrogen-bonding of water molecules to the surfactant headgroups and packing of the surfactant tails.

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