Hydrotrope induced structural modifications in CTAB/butanol/water/isooctane reverse micellar systems

Abstract

Designing nanostructures of desired morphology calls for development of new synthetic protocols to stimulate structural alterations in templates, modulating the architecture of nano-metric structures. The present study is an endeavor to investigate structural modifications in reverse micellar nanotemplates of a cationic surfactant system, CTAB/butanol/water/isooctane, as a function of hydrotrope concentration (sodium salicylate) and amount of water loading, W_x, in the micellar pool by synchrotron small-angle X-ray scattering. The micellar structural transition from a one-dimensional cylinder to a prolate ellipsoid can be controlled by tuning the water-to-surfactant molar ratio while the hydrotrope modulates growth of the micellar droplets. The inter-micellar interactions in these systems could be best represented by the Polymer Reference Interaction Site (PRISM) model at lower water content in the reverse micellar pool and by the Macroion model at higher water loadings. The location of the hydrotrope inside the micellar assembly and its interaction with different components of the reverse micellar system is probed with the help of ¹H NMR studies. The formation and tuning of anisotropic cylindrical/ellipsoidal reverse micellar droplets suggest promising application of such aggregates as “tunable soft templates” for fabricating fascinating nanostructures.