Translational self-diffusion in the smectic phases of ferroelectric liquid crystals: an overview

Abstract

In this work, we present our recent results obtained in the field of translational self-diffusion studies by means of ¹H NMR diffusometry in smectic phases formed by calamitic chiral liquid crystals. In particular, the diffusional behavior of chiral smectic phases with different clinicity, such as the ferroelectric and antiferroelectric phases, will be discussed on the basis of the results obtained on three different chiral smectogens. This research demonstrates that, despite previous assertions, out-of-plane translational diffusion in smectic phases is poorly affected by the clinicity of the phases, showing no discontinuity at the transition from synclinic to anticlinic structures, typical of the smectic C* phases. We can conclude that diffusion basically reflects the layered smectic structure where in-plane diffusion is much faster and less hindered than the out-of-plane one.

Keywords:

• liquid crystals
• synclinic, anticlinic
• diffusion
• ¹H NMR
• magnetic field
• ferroelectric
• anisotropy
• smectic
• chiral

Acknowledgments

The authors wish to dedicate this article to Professor Milada Glogarova for her collaboration in the field of liquid crystals and for the stimulating discussions on ferroelectric and antiferroelectric mesophases. This work has been supported by the Swedish Research Council VR. The authors are also grateful to Dr V. Hamplova and Dr M. Kaspar for providing the starting materials ZLLs and to Prof. I. Furó for helpful discussion.