Micelle and oligomer kinetics in aqueous solutions of n-octylammonium chloride: Monomer exchange, protrusion and chain isomerization

Polacek, Rüdiger; Kaatze, U.

doi:10.1016/j.molliq.2010.09.001

Cited by 5 publications

(10 citation statements)

References 36 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Ultrasonic excess attenuation per wavelength, α exc λ, at 25 °C displayed as a function of frequency, ν, for aqueous solutions of n -alkylammonium chlorides CH 3 (CH 2 ) n −1 NH 3 + Cl – ) with surfactant concentration near the cmc ( n = 5, c = 1.9 mol/L; n = 6, c = 1 mol/L; n = 7, c = 0.45 mol/L; n = 8, c = 0.26 mol/L). The dashed line represents a Debye-type relaxation spectral term with discrete relaxation time.…”

Section: Resultsmentioning

confidence: 99%

“…Ultrasonic excess attenuation spectra for aqueous solutions of HexACl (full symbols) and OcACl (open symbols) at different surfactant concentrations: ▼, c = 0.7 mol·L –1 ; ●, c = 1 mol·L –1 ; ▲, c = 1.5 mol·L –1 ; ◻, c = 0.18 mol·L –1 ; ○, c = 0.22 mol·L –1 ; Δ, c = 0.24 mol·L –1 . Lines are graphs of relaxation spectral function R H,D (ν) with parameter values as obtained by the regression analysis.…”

Section: Resultsmentioning

confidence: 99%

“…Spectra of OcACl solutions reveal up to three relaxation regions. A sum of three Debye terms R normalD , normalD , normalD false( normalν false) = ∑ i = 1 3 A D i ω τ D i 1 + ω 2 τ D i 2 + B normalν has been found appropriate …”

Section: Resultsmentioning

confidence: 99%

“…Relaxation rate 1/τ̂, corresponding with the maximum in the restricted Hill term (eq ), for some series of aqueous surfactant solutions at 25 °C displayed versus concentration difference Δ c = c – cmc: ▲, PeACl; ●, HexACl; ◼, HepACl; ▼, OACl; ○, SDS …”

Section: Discussionmentioning

confidence: 99%

“…In this paper spectra from this laboratory for aqueous solutions of n -pentylammonium chloride (PeACl, CH 3 (CH 2 ) 4 NH 3 + Cl – ) and n -hexylammonium chloride (HexACl, CH 3 (CH 2 ) 5 NH 3 + Cl – ) are discussed and are compared to previous results for solutions of n -heptylammonium chloride (HepACl, CH 3 (CH 2 ) 6 NH 3 + Cl – ) and n -octylammonium chloride (OcACl, CH 3 (CH 2 ) 7 NH 3 + Cl – ). All surfactant solutions were prepared by adding appropriate amounts of hydrochloric acid solutions to preweighted quantities of the respective n -alkylamine, always tracing the pH potentiometrically.…”

Section: Methodsmentioning

confidence: 97%

See 4 more Smart Citations

Kinetics of Micelle Formation and Concentration Fluctuations in Solutions of Short-Chain Surfactants

Kaatze

2011

J. Phys. Chem. B

View full text Add to dashboard Cite

To study the kinetics of surfactant systems below, at, and above the critical micelle concentration cmc, broad-band ultrasonic spectra of short-chain ionic surfactant solutions are evaluated. Within the measurement frequency range from 100 kHz to 4.6 GHz the spectra reveal a relaxation term that, at variance with the classical theory of micelle formation, is subject to a broad distribution of relaxation times. Analysis of the shape of this term evidences a coupling between the kinetics of micelle formation/disintegration and noncritical fluctuations in the local concentrations of surfactant monomers, oligomers, and micellar structures. A theoretical model, based on the assumption of a rate process in parallel to the fluctuations, applies well to the broadness of the experimental spectra. An initial increase in the concentration dependence of the principle relaxation time above the cmc is compatible with the high content of oligomers but is more distinctive than predicted by an extended model of micelle formation. The dependence of the relaxation amplitude upon surfactant concentration indicates incomplete dissociation of counterions. An additional high-frequency wing in the spectra is assigned to different structure factors of monomers and micelles. It may, however, also contain contributions from relaxations due to the formation/disintegration kinetics of oligomers and to the structural isomerization of surfactant alkyl chains.

show abstract

Section: Resultsmentioning

confidence: 99%

Section: Resultsmentioning

confidence: 99%