Use of a Dynamic Light Scattering Technique for SDS/Water/Pentanol Studies

Abstract

The interpretation of micelle/aggregate size obtained by use of the DLS technique for SDS/water/pentanol systems was discussed by comparison of the results of measurement with theoretical data. For most of the studied systems, the apparent radii (R _h,app ) did not satisfactorily characterize the size of the aggregates (R _h,app  < 1 nm). The use of a correction factor (f = 0.26) confirmed that the discrepancies were associated with the electrostatic intermicellar interactions. However, the fuzzy optical interface between dispersed and dispersing phases can also be the reason of such results. An increase of pentanol content caused a decrease of the droplet radius in w/o systems but in o/w systems the changes were negligible.

Keywords:

• Dynamic light scattering
• micelles
• microemulsions
• SDS/water/pentanol

Acknowledgments

The work was partly financed from budget of National Science Centre: No. N N310 777440, 2011–2014. The authors thank FEI Company (Eindhoven, The Netherlands) and its agency in Poland for the cryo-TEM investigation. Special acknowledgments are due to Sir Felix de Haas, Senior Research Scientist at the FEI Company, who performed the measurements. The authors thank Michael Kaszuba from Malvern Instruments Ltd. (UK) for many valuable comments on this work and the A.P. Instruments Company (Warsaw, Poland) for the reference PCS measurements.

Notes

The aggregation numbers according to: a,^{[ 29 ]} b,^{[ 41 ]} c^{[ 42 ]}.