Helical Twisting Power Dependence of Blue Phase Stability for Chiral Nematic Liquid Crystal

Abstract

In this study, we investigated blue phase (BP) temperature range and helical twisting power (HTP) using various types of chiral nematic liquid crystal (LC) mixtures composed of two kinds of chiral dopants and four kinds of host nematic LCs with different core structures. We found that chiral nematic LC mixtures containing three-ring core structure host nematic LCs such as 5CCB and 5CT presented small HTP values compared to those containing two-ring core structure host nematic LCs such as 5CB and 5CH regardless of chiral dopant species. We also found that the BP was not present when the HTP was of a magnitude less than 35.64 μm−1, that the BP temperature range increased when the HTP was of a magnitude between 35.64–49.03 μm−1, and that it decreased when the HTP was of a magnitude between 51.60 –63.03 μm−1 in cyano homologue chiral LC nematic LC mixtures.