Surface Alignment, Anchoring Transitions, Optical Properties and Topological Defects in Nematic Bent-Core Materials C7 and C12

This page lists questions we have about your paper. The numbers displayed at left can be found in the text of the paper for reference. In addition, please review your paper as a whole for correctness. We address the status of oxadiazole mesogens, C7 and C12, reported to show the biaxial nematic phase, by exploring material aspects (chemical stability, surface anchoring, optical and dielectric properties, topological defects) linked to the type of nematic order. We demonstrate that the isogyres splitting in conoscopic patterns of homeotropic state depends on sample thickness and is associated with variations 15 of molecular tilt along the normal to substrates. We observe isolated topological point defects (boojums and hedgehogs), as well as nonsingular ''escaped'' disclina-tions pertinent only to the uniaxial nematic order. Our conclusion is that C7 and C12 feature only a uniaxial nematic phase and the apparent biaxiality is caused by surface effects.