HIGH-PRESSURE OPTICAL MEASUREMENTS ON BP-III AND THE ISOTROPIC-PHASE OF A HIGHLY CHIRAL LIQUID-CRYSTAL

The optical activity and light transmission of the blue phases and iso tropic phase of ylphenyl)-4'-(2-methylbutyl)-4-biphenylcarboxylate (CE 2) are investigated under high pressure. The temperature ranges of the first (BP I) and third (BP III) blue phases show only the slightest c hange, if any, with increasing pressure. This is the first time BP III , a phase which is not understood at all, has been investigated under pressure. In addition, an alternative analysis to the one reported pre viously is reported which confirms that the pretransitional optical ac tivity in the isotropic phase changes very slightly due to pressure, a nd even this small change seems to be due to small changes in pitch an d index of refraction. Taken together, these observations indicate tha t high pressure has little effect on both the BP III phase and the tra nsition to the isotropic phase in highly chiral systems, even though t he BP III phase differs significantly from the other blue phases and s trong short range fluctuations make the transition appear continuous o ptically.