SANS Study of Micellar Structures on Oil Solubilization


Micellar structures of cationic alkyltrimethylammonium bromide (CnTAB) surfactants for different chain
lengths (n=12, 14 and 16) in aqueous solution on the addition of two oils benzene and hexane have been studied by
small-angle neutron scattering (SANS). Measurements have been performed for fixed 0.1 M concentration of surfactant
and oil. It is found that the size and the aggregation number of the micelles increase on oil solubilization with increase in
oil concentration. The effect is more pronounced for larger size of the micelles having longer chain length and also for
the oil benzene than hexane. The axial ratio of the micelles shows a large increase and the effective charge on the
micelles decreases on addition of oil. There is only a small increase in semiminor axis on addition of oil, which suggests
that distribution of oil is uniform inside the micellar core.
Keywords: Small-angle neutron scattering, micelles, oil solubilization.J. V. Joshit, V. K. Aswae and P. S. Goyal1
1UGC-DAE CSR, Mumbai Centre, Bhabha Atomic Research Centre, Mumbai 400 085, India
2Solid State Physics Division, BhabhaAtomic Research Centre, Mumbai 400 085, India