Persistence Length of Wormlike Micelles from Dynamic Light Scattering

A theoretical model for the dynamic structure factor of semiflexible macromolecules has been applied to recently published dynamic light scattering measurements on dilute micellar solutions of the surfactant sodium sulfopropyl octadecyl maleate (SSPOM) in the presence of NaCl (von Berlepsch; et al. Langmuir 1996, 12, 3613). Good agreement between theory and experimental data is achieved when a persistence length of about 120 nm is assumed. The computed initial decay rate at large scattering vectors remains approximately unchanged if polydispersity is taken into account. Thus, by studying the dynamic structure factor at large scattering vectors, the persistence length of wormlike micelles can be extracted.