Study of polymorphism of 4-hexyl-4'-isothiocyanatobiphenyl by complementary methods.

The results of adiabatic calorimetry, mid-infrared spectroscopy, X-ray diffraction, and polarized microscopy of 4-hexyl-4'-isothiocyanatobiphenyl are presented. Apart from the well-known isotropic liquid and smectic phases, calorimetric measurements indicate the existence of two stable crystalline phases. Quantitative analysis of infrared bands enabled the determination of phase transitions, observation of crystallization kinetics, and elucidation of the glass transition of the crystal-like smectic E phase. The structural information about the glass of the smectic E obtained from the diffraction studies is complemented by textures recorded by polarized microscopy.