Monomer Dynamics in Sds Micellar Solution: Quasielastic Neutron Scattering Study

Monomer dynamics in sodium dodecyl sulfate (SDS) micellar solution at room temperature as studied by quasielastic neutron scattering (QENS) technique is reported here. The elastic incoherent structure factor (EISF) obtained from the analysis of QENS data suggests that the SDS chain performs uniaxial rotational diffusion along the long molecular axis. The rotation diffusion coefficient is found to decrease with the increase in the concentration of the surfactants. It is also observed that on addition of electrolyte the motion is arrested. Addition of salt is known to induce the growth in SDS micelles, here it is found to affect the dynamics of monomers also. This is understood in terms of combined effect of closer packing of the monomers within the micelle and the tendency of amphiphilic molecules to stabilize due to the presence of electrolytes.