Measurement of rotational viscosity in the Smectic Cphase

Abstract

Several methods have been employed to determine the rotational viscosity γφ in the smectic C* phase associated with the molecular motion around the cone about the layer normal. We have measured this parameter using four different techniques and show that the values are in good agreement with each other. We have also studied the effect of chain length on γφ in the C* phase and γφ the viscosity associated with tilt angle fluctuations, in the A phase. The results suggest that the activation energy associated with these motions is basically controlled by the rigid core and not by the chain length of the molecule.