VISCOELASTIC PROPERTIES OF A LIQUID-CRYSTALLINE MONOMER AND ITS DIMER

Quasielastic-light-scattering measurements are reported for a dialkoxyphenylbenzoate monomer and its dimer in their respective nematic phases. The splay and twist elastic moduli of the dimer are found to be nearly independent of molecular length. The dimer's bend modulus, however, shows an anomalous increase with decreasing temperature well below the nematic-isotropic phase transition. Monomer viscosities are consistent with typical literature values, although gamma-1/eta(splay) and eta(bend) seem to be larger than expected for the dimer, where gamma-1 is the twist viscosity. The results are discussed in terms of viscoelastic properties of semiflexible rods. The elastic properties in particular are in good agreement with a recent model by Terentjev and Petschek (unpublished).