Nanoparticles Stabilized Monodisperse Foams of Long-term Stability*

Foams are found in a wide range of applications, such as detergents, food, cosmetic products and oil recovery. In many of these products and processes, microstructure and stabilization of foams play critical roles in determining their properties and performance. In these applications, colloids have emerged as an alternative stabilizing agent to replace traditional surfactants, because of their demonstrated effectiveness in stabilizing emulsions and particularly, as the particles can be manufactured using eco-friendly materials. But the structure-property relationships are not well studied. In this research, we apply microfluidic technique to produce mono-disperse bubbles generated using negatively charged silica nanoparticles modified by positively charged surfactant, cetrimonium bromide (CTAB). First, we generate foams microfluidically and tested their stability. We found that the stability of foams depends on the concentration of CTAB and nanoparticle. We then characterize the morphological and rheological properties of the foams for various bubble sizes, volume fractions, and nanoparticle concentrations.