Surfactant molecules have the ability to aggregate into a wide variety of highly dynamic nanostructures. The shape and size of the micelles depend on the type of surfactant and conditions such as temperature and solvent composition and have been extensively investigated the last century. However most studies relate to the statics, the structure and macroscopic properties such as surface tension, conductivity, foaming etc. [1]. Concerning the kinetics much less is known and very much limited to near-equilibrium relaxation studies. Here we take advantage of synchrotron-based time resolved small-angle X-ray scattering and follow typical non-equilibrium kinetic processes in surfactant micelle systems at millisecond-time scales [2,3]. We study an archetypical, simple surfactant system consisting of sodium dodecyl sulphate (SDS) in aqueous NaCl solutions and “film” a morphological transition from spheres to worm-like micelles using SAXS combined with stroboscopic stopped-flow schemes. The results show that worms are formed by fusion of globular micelles and short cylinders in a fashion that bears similarities to step-like polymerization mechanisms
References:
1. Holmberg, K.; Jönsson, B.; Kronberg, B.; Lindman, B. Surfactants and Polymers in Aqueous Solution; Wiley, 2002.
2. G. V. Jensen, R. Lund, J. Gummel, M. Monkenbusch, T. Narayanan, and J. S. Pedersen, J. Am. Chem. Soc., 2013, 135, 7214–7222.
3. R. Lund, L. Willner, M. Monkenbusch, P. Panine, T. Narayanan, J. Colmenero, and D. Richter, Phys. Rev. Lett., 2009, 102, 188301.
4. G. V. Jensen, R. Lund, J. Gummel, , T. Narayanan, and J. S. Pedersen, submitted.
reidar.lund@kjemi.uio.no
