Thermodynamic properties of n-alkanes in porous graphite

Differential scanning calorimetry on very thin layers of n-alkanes confined in the pores of delaminated graphite is reported. The thermodynamic behaviour of the strongly adsorbed component at the graphite surface and the apparently 'bulk-phase' component (from the point of view of X-ray diffraction) is analysed. The adsorbed phase is of the same crystalline form whatever the parity of the n-alkanes and has the same thermodynamic properties, as revealed by differential scanning calorimetry. A study of the solid-solid and solid-liquid transitions of the 'bulk phase' confined in the pores shows that the solid-solid transition is the most affected by the confinement in the pores and its temperature is decreased.