Surface phase transitions at liquid-mixture/solid interfaces

In an adsorption study from a liquid mixture, the choice of a moderately hy drophilic silica and of a solute like 2,5-dimethylpyridine (2,5-DMP), known for its layering ability in dilute solution in water, allows the observati on of several adsorption gaps on the isotherms established at different tem peratures. These gaps may be attributed to surface phase transitions. Colle cted on a (T-Gamma(21)) diagram, they constitute a surface phase diagram hi ghly similar to the bulk water-2,5 DMP liquid-solid diagram at low temperat ure. It is the first example of a surface phase diagram at a liquid-mixture /solid interface.