- no.2004, pp.270-271, 2004-09-26
We have found the new types of photonic liquid crystal, SmBP_<Iso> Phase, which shows the uniform isotropic iridescent color strongly dependent on the concentration, chirality and temperature for the first time. SmBP_<Iso> has both the finite local order parameter of the helix of the orientation and the smectic layer simultaneously, but spontaneously achieves complete isotropic nature in optical wave-length without any discontinuity in mesoscopic length scales. It was confirmed by visco-elastic measurement that the SmBP_<Iso> should be originated from the anomalous softening of the smectic layers due to the freezing effect on the molecular fluctuation induced by the introduction of the connection of the molecules. We expected that the random distribution of the distinct helix in 3-dimensional space can be stabilized by the apparent elastic long-range interaction "field" produced by the deformation of the smectic order. We have also first recognized two different types of thermodynamic phase transitions among SmBP phases, order-disorder transition for the spatial arrangement of the helix and the transition of the connectivity of smectic layers, which are attributed to the transition of the spatial distribution of the both orders, not belong to the order parameters themselves.