engleski

Homeotropic alignment of mesogenic dimers in the nematic and twist-bend nematic phases

The recently discovered twist-bend nematic phase, NTB, has attracted much attention with its spontaneous bend distortion and short-pitch heliconical structure. Investigations of these materials from basic and applied perspectives require reliable surface alignments: planar and homeotropic. However, while planar alignment is common, no homeotropic alignment was achieved so far with NTB–forming dimers. Here, we report on the surface alignment of dimers belonging to the salicylaldimine homologous series and their mixtures. Good homeotropic alignment of these materials was obtained in both N and NTB phases with standard alignment layers We discuss the origin of these instabilities, which are not observed in a similar cell filled with a rod-shaped nematic. We also analyze the relation between the chemical structure of the bent-shaped molecule and its ability to align homeotropically.

twist-bend nematic phase ; homeotropic alignment

nije evidentirano