BLUE PHASE MIXTURES EXHIBITING LOW FRACTIONS OF A CHIRAL COMPOUND EXPERIMENTAL-OBSERVATION OF SOME UNUSUAL PROPERTIES

We have used chiral compounds with very high helical twisting power as components in induced-cholesteric mixtures in order to obtain new blue phase systems. In one of these mixtures an unusual large blue phase temperature range of more than 10 K was observed. The lattice constant of the BPI in this system increases strongly with increasing temperature, a behaviour observed for the first time. The threshold voltage for the field-induced BP/cholesteric phase transition in this mixture decreases with increasing temperature. Thus the reentrant phase sequence cholesteric phase-blue phase-cholesteric phase-isotropic phase can be observed with increasing temperature if an electric field is applied to the sample. © 1990 Taylor & Francis Group, LLC.