Static and dynamic studies on cycloheptanol as two-orientational glass-former

Two-orientational glass transitions of two different orientationally disordered states of cycloheptanol are investigated and compared through static (thermodynamic and X-ray diffraction) as well as dynamic (dielectric spectroscopy) experimental techniques. What makes cycloheptanol unique is that one of these disordered states presents an isotropic lattice while for the other the lattice is anisotropic and the orientational glass transition temperature of the anisotropic-glassy state is found to be higher than that of the isotropic one. This result is discussed through the fragility concept, being consistent with the Adam-Gibbs theory. In addition, the kinetic fragilities through (F1/2-metric) as well as the thermodynamic fragilities through ((ΔTgl/TglA)-metric) of both states seem also to correlate in a consistent way.