J. Phys. II France
Volume 3, Numéro 5, May 1993
Page(s) 597 - 602
DOI: 10.1051/jp2:1993153
J. Phys. II France 3 (1993) 597-602

Viscoelastic properties of a bent and straight dimeric liquid crystal

Gregory A. DiLisi1, E.M. Terentjev2, Anselm C. Griffin3 and Charles Rosenblatt1

1  Department of Physics, Case Western Reserve University, Cleveland, Ohio 44106 U.S.A.
2  Cavendish Laboratory, University of Cambridge, Cambridge CB3 0HE, Great-Britain
3  Melville Lab for Polymer Synthesis, University of Cambridge, Cambridge CB2 3RA, Great-Britain

(Received 27 November 1992, revised 15 March 1993, accepted 19 March 1993)

Absolute values for the elastic constants and viscosities are reported in the nematic phase for two dimers based upon the monomer 4.4'-dipentyloxyphenylbenzoate. One dimer has an even number of methylene units in the spacer and, in consequence, is approximately straight in the all-trans conformation. The other dimer has one less methylene unit, and is therefore bent. We find that the ration K33/K11 for the odd dimer is reduced relative to that for the even member of the series. Moreover, we find that the absolute elastic constants for the odd dimer are of order one-half that of the even dimer. the system is analyzed in terms of recent theories by Terentjev, Rosenblatt, and Petschek, and by Terentjev and Petschek, with results in reasonable agreement with experiment.


© Les Editions de Physique 1993