Phase transitions in Langmuir monolayers

Some fatty acids, lipids, polymers and mesogenic molecules which are amphiphilic in nature spread at the air-water interface to form stable Langmuir monolayers. They exhibit a rich variety of two-dimensional (2D) phases. In this article, we briefly review some of the novel features we have found in these monolayers. For example, we find transition from a 2D monolayer to three-dimensional structures possessing liquid crystalline order, induced liquid condensed phase, demixing of liquid expanded phase, critical points and pattern formation.