Phase transformations for cyclohexane in mesoporous silicas

Neutron diffraction (ND), nuclear magnetic resonance (NMR) and differential scanning calorimetry (DSC) studies have been used to study the structural features of cyclohexane in the confined geometry of several mesoporous silicas with a pore size in the range 25–500 Å. The results show a consistent depression of the nucleation temperature that is inversely proportional to the pore size and appear to be related to the orientational correlations in the various phases. In the extreme case of MCM silicas, there is evidence that nucleation is completely suppressed.