Helical Twisting Power in Mixtures of Nematic and Cholesteric Liquid Crystals

Chirality in Mixed Nematic and Cholesteric Liquid Crystals

“…In recent publications a similar spectral behavior was reported by Nakagiri et aI, in a mixture of cholesteryl propionate (CP) and MBBA (2), and in a mixture of CP and p-azoxyanisole (PAA) (3). However, the MPV was not observed in a mixture of CP and p-cyanobenzylidene-p'-phenetidine (CBP) (3) where at high concentrations of CP a saturation is observed instead.…”

“…To explain their results and MPV's at higher concentrations, Nakagiri et al (2,3) further extend this theory, and by calculating the second order perturbation energy, introducing the quadropole-quadropole interaction as well, show that the dependence of pitch Z on concentration C of the optically active molecule is of the form:…”

“…1 relates to a mixture of CP and MBBA (2), where a MPV is reached at appro 70 wt. % of CPo CP, which forms a LH helix, will induce LH stacking in the MBBA solute.…”

Macroscopic Torsional Strain and Induced Molecular Conformational Deracemization

“…It is well known that chiral LC molecules, or even achiral molecules doped with a chiral agent, result in a macroscopic helical twist of the director n with a characteristic inverse pitch 1 b p − in the bulk that is sensitive to the molecular structure [6,7]. Such twisted, optically-birefringent helices can rotate the polarization of light and exhibit photonic band gaps.…”

Composition and Temperature Dependence of the Pitch in Cholesteric Binary Mixtures

“…Adams and Haas;' Nagakiri, Kodama and Kobayashi ; 6 Stegemeyer and Finkelmann ;7 Pochan and Hinman; 8 Kozawaguchi and Wada;' Wulf;" Bak and Labes;" and the present authors").…”