Evidence for Secondary Minimum Flocculation of Stöber Silica Nanoparticles at the Air−Water Interface: Film Balance Investigations and Computer Simulations

摘要: The interactions of Stober silica nanospheres having diameters ca. 40, 100, and 200 nm were studied at the water−air interface with a Wilhelmy film balance. particle sizes size distribution functions determined from TEM measurements. According to in situ Brewster angle microscopy investigations calculated DLVO interparticle energies, particles formed weakly cohesive films interface; hence, increasing surface pressure during compression was attributed repulsion. repulsion energies that versus area isotherms exceeded by 2−3 orders magnitude. extremely high dipole−dipole interactions. Despite repulsion, monolayer state prior recently recognized long-range attractions capillary electrostatic origin. p...