THERMAL AND VIBRATIONAL INVESTIGATION OF CRYSTAL NUCLEATION AND GROWTH FROM A PHYSICALLY CONFINED AND SUPERCOOLED LIQUID

Differential scanning calorimetry and temperature-dependent Raman-scat tering investigation of 2,4,6 trinitrotoluene (TNT) confined in four d ifferent pore-sized silica hosts have been conducted. The results sugg ested that (i) nucleation occurs at the pore center rather than at the pore walls; (ii) although the freezing transition of the bulk has a v olume reduction of about 10%, the freezing transition of the confined phase maintains its interconnectivity; (iii) that TNT confined in 10-n m pores without bulk on the outer surface shows no freezing transition upon cooling and shows recrystallization and melting transitions upon heating suggests that the characteristic curves of nucleation and gro wth are modified resulting from the surface and physical confinement e ffects. In addition, our Raman study suggests that (i) the freezable c onfined TNT retains the similar solid structure to its bulk; (ii) the TNT physically confined in d(p) less than or equal to 5-nm pores may e xist in a cluster form.