Polymers Extend Range of Blue Phase

Blue-phase liquid crystals display much promise in photonics -- for example, in switching applications -- but their temperature sensitivity has made their deployment problematic. Now a team at Kyushu University, Precursory Research for Embryonic Science and Technology and Fukuoka Industry, Science and Technology Foundation, all in Japan, has demonstrated that the addition of a polymer to the liquid crystal can extend the temperature range of the blue phase from 1.1 K to more than 60 K.

Reporting in the September issue of Nature Materials, the researchers describe how altering the composition of polymer/liquid crystal mixtures influences the temperature range of the blue phase. They determined the transition temperatures from chiral nematic to blue phase and from blue phase to isotropic liquid phase by imaging the samples under a polarizing optical microscope and monitoring the changes in their reflectance spectra.