Mechanically tuned lanthanum carbonate nanorods in water-in-oil microemulsion scaffolds

Abstract

This study provides a deeper insight of the growth process (a 120-min study) of lanthanum carbonate nanorods within the polar core of W/O microemulsions, produced by Toluene/Tween 80/ 1-butanol. Field emission electron microscope (FESEM), Transmission electron microscope (TEM) and dynamic light scattering (DLS) have been used to measure the growth of nanostructures. Spherical droplets are formed during the initial nucleation dominant growth period (5–15 min). These enlarge with the course of reaction and at the transient time (15–30 min), deviate from spherical shape due to anisotropic growth. Nanorods evolve as a consequence of these deformation and enlargement along the longer axis. After 120 min of the reaction, larger dimension nanorods are achieved. The double bond present at the hydrophobic tails of Tween 80 may responsible for the breaking of symmetry (anisotropic growth) during the growth phase of nanorods. At the transient time, due to pi-pi interaction along the longer axis among Tween 80 surfactant molecules, causes spherical nanostructures to deform into nanorods. Now, surfactant molecules strongly bind with water in the hydrophilic inner core at low water content (W0 = 10) and reduces the possibility of intermicellar exchange between reverse micelle and reactants mixing and, consequently, contributes to the slow growth of nanoparticles that relatively small in size compared to high water content (W0 = 50) microemulsion media.