Elasticity and orientational order in some trans-p-n-alkoxy-α-methyl cyanophenyl cinnamates

Abstract

The splay (k₁₁), twist (k₂₂) and bend (k₃₃) elastic constants determined by the Freedericksz method and the orientational order parameters (s) derived from optical measurements in the nematic phase of six homologues of trans-p-n-alkoxy-α-methyl cyanophenyl cinnamates (n OMCPC) are reported. The data close to the nematic-isotropic transition point (T_NI) are compared with T_NI and the heats of transition (ΔH). The temperature-variation of elastic constants is discussed in terms of existing theories. The pretransitional increase in the twist and bend constants near the nematic-smectic A transition point (T_NA) of 10 OMCPC has also been analysed.