BEND ORIENTATIONAL DIFFUSIVITY MEASUREMENT BY LIGHT BEATING SPECTROSCOPY IN A DISK-LIKE THERMOTROPIC NEMATIC PHASE (ND)

Abstract Using a light-beating technique for an appropriate scattering geometry, we have measured the bend orientational diffusivity (D bend) for an “hexa-n-alcanoyloxytruxene” (HATXC12H25) sample which exhibits a disk-like thermotropic nematic phase (ND ) between 57°C and 84°C. From K 33 measurement by the Frederiks method, the bend viscosity (ηbend) is deduced. It is about 100 times higher than those corresponding to rod-like thermotropic nematics. From previous measurements of D splay and D twist for HATXC12H25, we have deduced the elastic constants (K 11 K 22) and the viscosities (ηsplay, ηtwist). It has been concluded that, although there is a difference between the two kinds of molecules (disk-like and rod-like), the backflow has the same effect as in rod-like nematic phase.