Interfacial Activity of Polymer Grafted Nanoparticles

The oil-water interfacial tension is reduced when nanoparticles segregate to the oil-water interface and this segregation is governed by the interparticle interactions of the nanoparticles. In this study, hydrophilic polymers or hydrophilic-oleophilic copolymers were grafted from silica nanoparticles using a living radical atom transfer polymerization in order to tune the interparticles interaction. We have studied the nature of interparticle interactions of such nanoparticles using interfacial tension measurements, and their structure using small angle X-ray scattering. Amphiphilic polymers grafted from nanoparticles promote their segregation to the interface and make it possible to reduce the hexane-water interfacial tension significantly. Moreover, the hybrid particle size was the dominant variable in determining the critical micelle concentration and could be manipulated by changing the molecular weight and grafting density of polymer brushes. The results of this study can be applied to the development of particle-based oil dispersants or enhanced oil recovery agents to improve their efficiency and performance.