Spread monolayers: Structure, flows and dynamic self-organization phenomena

Condensed matter physics is facing new challenges and opportunities raising from the vast and increasingly attractive field of soft materials and complex fluids. Here, we concentrate on one of the simplest experimental examples by reviewing different structural and dynamical properties of spread (Langmuir) monolayers. Our interest goes beyond an equilibrium description to stress experiments and models oriented to unveil dynamic responses either following relaxation or externally controlled forcing processes. We choose to focus on mesoscopic phenomena that reflect the pattern of self-assembly of the constituent molecules. We start by reviewing basic structural and textural aspects of Langmuir monolayers. Probably the most classical nonequilibrium phenomena one can envisage when referring to complex fluids concern flow properties. Thus, rheological experiments conducted with Langmuir monolayers are briefly commented next. Finally, new scenarios of collective self-organization are discussed from experiments and models, revealing unexplored dynamic self-assembling capabilities of Langmuir monolayers.