Effect of surfactant concentration, solvents and particle size on ∏-A isotherm of silica nanoparticles

We present here, the effect of surfactant concentration, different solvents and particle sizes on isotherm of silica nanoparticles at air/water interface. The experiments were performed by Langmuir-Blodgett (LB) technique and pressure ∏-A isotherms were recorded. Silica nanoparticles (NPs) of different sizes namely; 30 nm, 150 nm and 630 nm, were synthesized by Stöber's method and characterized by using scanning electron microscopy to determine their sizes and dispersity. As-synthesized NPs were hydrophobized to varying extents through addition of varying amounts, ranging from 0.5 mg to 1.5 mg, of the cationic surfactant, cetyltrimethylammoniumbromide (CTAB). Effect on lift off area (area/particle) and corresponding yield were investigated and reported. This parametric study can adds on in meeting the requirement of reproducibility of LB films.