Papers by Keyword: Cholesteric

Abstract: A new series of two-arm (MB1, MB2), four-arm (MB3), six-arm (MB4) chiral liquid crystalline compound containing isosorbide as chiral core were first synthesized. Four precursors of branched-arm B1~B4 were obtained at first and then were esterized separately with isosorbide and got four chiral branched-arm liquid crystals (MB1~MB4). The chemical structures and LC properties of the liquid crystalline molecule were measured by spectrum and thermal analysis techniques. XRD curves of MB1~MB4 samples only showed broad peaks at wide-angle, but no sharp peak was seen for all the samples. The results showed that MB1~MB4 appeared cholesteric phase with oily streak texture or lined texture and finger print texture. Isosorbide successfully induced cholesteric phase. The values of melting point and clearing point for MB1~MB4 decreased. The quantity of branched-arm and chiral core had effects on their liquid crystalline properties.

Abstract: In the present work, a ester of glucose (a) with 4-(4-(ethoxybenzoyloxy) phenoxy) -6-oxohexanoic acid side–arms has been synthesized. Compared with b and c, reported previously, a had the same side-arms but different chiral core. The phase behaviors of three star-shaped liquid crystals (a, b, c) have been compared and studied, and the effect of the different structure of chiral core on the phase behaviors of the star-shaped liquid crystals has been discussed. a, b and c displayed cholesteric phase, unlike the nematic side arm. a, b and c were all laevo-rotationary, unlike their parent cores. The melting temperature of a, b and c decreased with the increase of the sugar ring of the chiral core. The mesomorphic region of a on cooling cycle was wider than that on heating cycle. For b and c, the case was similar.

Abstract: We demonstrate a polymer-stabilized cholesteric liquid crystal (PSChLC) where the reflected color can be electrically-switched to reflect a different color at a shorter wavelength (blue-shift). A polymerizable additive formulation is used to ensure a wider range of color tuning and anisotropic reflection where on side reflects and the other side transmits the incident light in response to applied voltage. A second electrically switched color based on polymer-stabilized blue phase (PSBP) liquid crystal is also demonstrated. Applying an electric field across the cell results in a red-shift in Bragg reflected wavelength due to the electrostriction effect. These switchable color devices of are color filters and polarizers free which are suitable for electronic papers.