Spontaneous formation of multilamellar vesicles from aqueous micellar solutions of sodium linear alkylbenzene sulfonate (NaLAS)

Abstract

This is a repository copy of Spontaneous formation of multilamellar vesicles from aqueous micellar solutions of sodium linear alkylbenzene sulfonate (NaLAS).

Micellar structure and transformations in sodium alkylbenzenesulfonate (NaLAS) aqueous solutions: effects of concentration, temperature, and salt

“…4b) and then optically visible precipitation occurs in the solutions. Comparison of the current DLS findings and structural transformations reported in similar systems, [57][58][59] suggests that NaLAS micelles first elongate to form cylindrical structures before yielding larger assemblies such as multilamellar vesicles, previously reported for NaLAS solutions under other thermodynamic conditions 23 or external flow fields. 22 These postulated structures are illustrated in Fig.…”

“…Scattering Length Densities (SLD) of the sodium sulfonate shells (C5 Å thickness) and carbon chain tails (C13-15 Å length) were initialised at 1.69 Â 10 À6 Å À2 and À0.46 Â 10 À6 Å À2 , respectively, based on our previous work. 23 For clarity, details of SLD calculations and profiles are provided in ESI, † Section S3. No significant variation in the fitted SLD values were found upon increasing the concentration of NaLAS in binary mixtures, see ESI, † Fig.…”

“…Fig. 2a shows the SANS data and fits obtained with a core-shell prolate ellipsoidal model for the form factor P(Q), and the Hayter-Penfold Rescaled Mean Spherical Approximation RMSA for the structure factor, S(Q), 22,23,28,45 available in SASView.…”

“…An average d-spacing is calculated at 3.3 AE 0.3 nm, consistent with previous reports. 23,62 The peak intensity increases with added salt (above the required threshold value), corresponding to a higher volume fraction of lamellar phase, and then appears to decrease (ESI, † Fig. S11b).…”

“…1b). 23,24 The effect of surfactant concentration on the shape and size of their micelles has been extensively reported for anionic, cationic and zwitterionic surfactants using small angle X-ray and neutron scattering techniques (SAXS and SANS). [25][26][27] Heating solutions of anionic sodium dodecyl sulfate (SDS) above room temperature was found to shrink ellipsoidal micelles.…”