THERMODYNAMIC CHARACTERIZATION OF VAPOR-DEPOSITED AMORPHOUS SOLID

An adiabatic calorimeter designed for vapor-deposited sample has been applied to two molecular liquids, butyronitrile and l-pentene, in order to characterize amorphous solid produced by vapor condensation. Comparisons are made between thermodynamic behavior of the vapor-deposited (VQ) and liquid-cooled (LQ) amorphous solids of both samples. It can be concluded that both the LQ and VQ solids exhibit essentially the same phenomena; the glass transition, residual entropy, and enthalpy relaxation. These are the reflection of the metastability and the non-equilibrium nature of both amorphous solids. From a quantitative viewpoint, however, the two types of amorphous solid behave differently. The VQ samples show the enthalpy relaxation occurring just above the temperature of deposition, and have larger residual entropy compared to the LQ samples. These results indicate the effective extraction of the kinetic energy of molecules during the process of condensation from vapor to amorphous solid.