J. Phys. II France
Volume 2, Numéro 3, March 1992
Page(s) 521 - 528
DOI: 10.1051/jp2:1992146
J. Phys. II France 2 (1992) 521-528

Twist viscosity coefficient of a dilute solution of the main-chain mesogenic polymer in a nematic solvent : an estimation of the anisotropy and the rotational relaxation time of polymer chains

Evgeniy E. Pashkovsky and Tamara G. Litvina

Institute of Macromolecular Compounds, Academy of Sciences of the U.S.S.R., Bolshoi pr. 31, St. Petersburg 199004, Russsia

(Received 22 July 1991, accepted 15 November 1991)

The dynamics of Freederiks transition at bend deformation in the magnetic field was used to study the visco-elastic properties of a dilute solution of mesogenic main-chain polymer in a low molecular weight nematic liquid crustal pentylcyanobiphenyl (5CB). Analysis of obtained data based on Brochard's theory for polymer chains in the nematic environment provided the temperature dependences for the anisotropy $R_{\parallel}/R_{\perp}$ of chains (where $R_{\parallel}$ and $R_{\perp}$ are dimensions parallel and perpendicular to the nematic director) and for the rotational relaxation time of chains $\tau_{\rm R}$. The value of $R_{\parallel}/R_{\perp}$ decreased with temperature from 1.85 to 1.75 and $\tau_{\rm R}$ decreased according to the Arrhenius law.

61.30G - 61.40K - 62.10

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