Phase transition of physically confined 2-decanol: effect of bulk

We have studies the melting and freezing behaviors of physically confined 2-decanol inside porous silica using a differentials scanning calorimeter. The melting temperature of the confined 2-decanol decreased as the size of the pores confining it decreased in agreement with the Gibbs-Thomson equation. The freezing temperature of the confined 2-decanol, however, was dependent whether there was bulk 2-decanol outside the pores or not. 2-decanol confined in larger pores crystallized using the bulk outside the pores as a nucleating site and went under phase transition at a higher temperature in comparison to 2-decanol confined without bulk. The freezing temperature of 2-decanol confined in smaller pores, however, was not influenced by the presence or lack of the bulk outside the pores. The distinction between the large and small comes from the comparison of melting point of the confined 2-decanol to the freezing point of the bulk 2-decanol. When the melting point of the confined 2-decanol is smaller than the freezing point of the bulk 2-decanol, then the bulk does not act as a nucleation site for the confined 2-decanol.