Effects of an asymmetric dimer on a phase sequence of a blue phase material

Abstract

We prepared some amorphous blue phase (BPIII) materials doped with an asymmetric dimer (I-n) in which phenylpyrimidine and cyanobiphenyl units were connected via a flexible spacer. We investigated their phase transition behaviour depending on the parity of the spacer. The BPIII materials doped with a small amount of an even-membered asymmetric dimer exhibited a phase sequence of isotropic liquid–high temperature chiral nematic (N*H)–BPIII–low temperature chiral nematic (N*L). Applying electric filed in the N*H, it changed to the nematic phase. The nematic phase did not reverse to the N*H phase but changed to BPIII upon removal of the electric field. The BPIII materials with a large amount of an odd-membered asymmetric dimer showed the BPIII with a temperature range of more than 30 K.