De Vries smectic A phase formed by a liquid crystal side chain copolymer? A ¹³C NMR study

Abstract

We study the orientation and order parameter of a liquid crystalline random side chain copolymer by ¹³C NMR. Evidence has previously been presented that this material forms a de Vries smectic A phase. The NMR data show that the molecular tilt angle in the smectic A phase is very small or zero and the smectic A–smectic C* transition is attributed predominantly to a change of the molecular tilt rather than azimuthal ordering. We discuss the NMR results in the context of earlier X‐ray and elastic characterizations of structurally similar materials.

Acknowledgements

Financial support from the DFG within grant Sta 425/14 is gratefully acknowledged.