Ionic amphiphile stabilized reverse micellar systems and their implications for nanoencapsulation

Hypothesis: Encapsulation of core nanoparticles using reverse micelles is a widely used approach owing to its effective organization. Hence, it is of value to analyze the physicochemical mechanisms associated with the reverse micelle-based encapsulation for the choice of appropriate surfactant for the encapsulation process. The presence of ionic micelles, catalyst ions and surface charge of the core nanoparticles are expected to influence the stability of reverse micelles. Hence, it is of value to find the optimized conditions for stable reverse micelles formation through understanding the multiple double layer formation inside of ionic reverse micelles. Experiments: Reverse micelle systems stabilized by non-ionic, anionic and cationic surfactants are formulated with the presence of ammonia ions and negatively charged core nanoparticles. The structure of reverse micelles is studied by measuring its average hydrodynamic diameter and optical transmittance measurements. Shell encapsulation experiments are performed in stable and unstable reverse micellar structures. Findings: Ionic surfactants help to form stable reverse micellar structures. Multiple double layers formation is explained in ionic reverse micelles for the first time. Magnetite@silica is chosen as a model system to demonstrate the observed effects. The results obtained could remove the complexity in understanding the ionic reverse micellar systems for the functionalization of nanoparticles.