J. Phys. II France
Volume 1, Numéro 7, July 1991
Page(s) 821 - 830
DOI: 10.1051/jp2:1991100
J. Phys. II France 1 (1991) 821-830

Smectic order and backbone anisotropy of a side-chain liquid crystalline polymer by Small-Angle Neutron Scattering

L. Noirez1, G. Pépy2, P. Keller1 and L. Benguigui2

1  Laboratoire Léon Brillouin, CEN-Saclay, 91191 Gif-sur-Yvette Cedex, France
2  Solid State Institute Technion, 32000 Haifa, Israël

(Received 12 November 1990, revised 18 March 1991, accepted 22 March 1991)

We have simultaneously measured, for the first time, the extension of the polymer backbone of a side-chain liquid crystalline polymer and the intensity of the 001 Bragg reflection, which gives the smectic order parameter $\Psi$ as a function of temperature in the smectic phase. We have qualitatively demonstrated that the more the smectic phase is ordered, the more the polymer backbone is localized between the mesogenic layers. It is shown that the Landau theory allows us to relate the radius of gyration parallel to the magnetic field of the polymer backbone to the smectic order parameter. We also show that the Renz-Warner theory is suitable at low temperatures.

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