Equilibrium capillary forces in colloidal systems
Joris Sprakel (Wageningen University, NL)

In this presentation recent experimental findings will be presented, that evidence fully equilibrated capillary forces in colloidal systems, measured with Colloidal Probe Atomic Force microscopy. The reversible nature of the forces that result from capillary condensation, can be explained with simple arguments based on nucleation and growth mechanisms. Furthermore we show that the force-distance profiles can be analysed in terms of the interfacial tension between the coexisting phases (the capillary bridge and the excess bulk phase). For the systems investigated, this has evidenced ultra-low interfacial tensions, of the order of microN/m. Finally, some work-in-progress on the mesoscopic modelling of capillary condensation, using self-consistent field theory, will be briefly adressed.