Forces between polystyrene surfaces in water–electrolyte solutions: Long-range attraction of two types?

摘要: A great deal of effort has recently been focused on the experimental studies phenomenon long-ranged attraction between identically charged colloidal (polystyrene) particles immersed in an electrolyte. The theoretical validation suggested need for revision existing and established theories assuming observed is electrostatic origin. We, however, demonstrate that a number reasons (first all hydrophobicity roughnessof particles) Derjaguin–Landau–Verwey–Overbeek (DLVO) behavior should not be expected polystyrene surfaces. Indeed, force measurements with atomic microscope-related set-up suggest even within one pair interacting surfaces, attractive interaction various types can observed. There usually difference first approach later ones. characterized by short-range jump into contact. Depending conditions (electrolyte concentration, previous contacts etc.) there exists late two type abrupt from maximum repulsive force, which typically longer-range than approach. This most likely due to submicroscopic bubbles trapped and/or formed (and separation) second weak exponentially decaying.