Langmuir Monolayers of Bent-Core Molecules

A systematic study of five different, symmetric bent-core liquid crystals in Langmuir thin films at the air/water interface is presented. Both the end chains (siloxane vs hydrocarbon) and the core (more or less amphiphilic) are varied, to allow an exploration of different possible layer structures at the interface. The characterization includes systematic surface pressure isotherms, Brewster angle microscopy, and surface potential measurements. The properties of these layers are strongly dependent on the individual type of molecule:  the molecules with amphiphilic end chains lie quite flat on the surface, while the molecules with hydrophobic end chains construct multilayer structures. In both cases, the three-dimensional collapse structure is reversible.