Electroclinic effect in a chiral carbosilane-terminated 5-phenylpyrimidine liquid crystal with ‘de Vries-like’ properties

Christopher P J Schubert,Frank Giesselmann,Robert P Lemieux,Carsten Müller,Michael D Wand

doi:10.1039/c5cc05212b

Abstract

The chiral carbosilane-terminated liquid crystal 2-[(2S,3S)-2,3-difluorohexyloxy]-5-[4-(12,12,14,14,16,16-hexamethyl-12,14,16-trisilaheptadecyloxy)phenyl]pyrimidine () undergoes a smectic A*-smectic C* phase transition with a maximum layer contraction of only 0.2%. It exhibits an electroclinic effect (ECE) comparable to that reported for the 'de Vries-like' liquid crystal and shows no appreciable optical stripe defects due to horizontal chevron formation.

Highlights

The chiral carbosilane-terminated liquid crystal 2-[(2S,3S)-2,3difluorohexyloxy]-5-[4-(12,12,14,14,16,16-hexamethyl-12,14,16-trisilaheptadecyloxy)phenyl]pyrimidine (QL32-6) undergoes a smectic A*-smectic C* phase transition with a maximum layer contraction of only 0.2%
The chiral smectic A (SmA*) liquid crystal phase is characterized by an analog electro-optical effect known as the electroclinic effect that makes it possible to generate a gray scale in display applications on a much faster time scale than a nematic LCD.[1]
This electroclinic effect (ECE) is described by a phenomenological model derived from Landau theory that predicts a linear dependence of the induced tilt angle y on E at low field strengths; this relationship deviates from linearity when the temperature approaches the transition point TAC from the orthogonal SmA* phase to the tilted SmC* phase.[4,5]

Summary

Introduction

The chiral carbosilane-terminated liquid crystal 2-[(2S,3S)-2,3difluorohexyloxy]-5-[4-(12,12,14,14,16,16-hexamethyl-12,14,16-trisilaheptadecyloxy)phenyl]pyrimidine (QL32-6) undergoes a smectic A*-smectic C* phase transition with a maximum layer contraction of only 0.2%. It exhibits an electroclinic effect (ECE) comparable to that reported for the ‘de Vries-like’ liquid crystal 8422[2F3] and shows no appreciable optical stripe defects due to horizontal chevron formation.

Results

Conclusion