Reentrant isotropic phase and enhanced blue phases in mixtures of chiral calamitic and achiral bent-core molecules

Abstract

Binary mixtures of two liquid crystals, one composed of chiral rod-like (R) and the other of achiral bent-core (BC) molecules, were investigated in order to obtain stable long range blue phases (BPs). While highly chiral BPs were found to be enhanced, the chiral nematic and chiral smectic C⁎ phases were suppressed and a long range non-chiral smectic A phase induced. Another interesting offshoot was the formation of a reentrant isotropic phase which has not been observed earlier in such systems. The results have been interpreted based on self-assembly of the R and BC molecules and the interplay of molecular chirality of the R molecules and conformation chirality of the BC molecules. The study demonstrates how phase behaviour and chirality in binary mixtures are closely connected with the specific molecular structures of the components and that a proper choice is essential for the design of new chiral materials for technological applications.