Phospholipidic Monolayers on Formamide

We report the first phase diagram of a Langmuir film at the air-formamide inter- face. Stable films of phospholipids such as DPPC or DSPC undergo phase transitions observed on isotherms or by fluorescence microscopy. They display bidimensional gas, liquid and solid phases, as well as two mesophases, the latter coexist with liquid on a sharp first-order transition plateau. We compare these observations with known results on films on water.