Polar order in columnar phase made of polycatenar bent-core molecules
Chemistry Department, Warsaw University, Al. Zwirki i Wigury 101, 02-089 Warsaw, Poland,
Department of Organic and Polymeric Materials, Tokyo Institute of Technology,
The columnar phases made of polycatenar molecules with bent shaped mesogenic core are studied. The polar order in this system is associated with the change of the column building blocks from flat discs (Colh phase) into cones (ColhPA phase), which allows for axial polarization of the columns. The nature of Colh and ColhPA phase transition changes from the first order for short homologues to continuous for the longest one. This can be attributed to decreasing intercolumnar interactions due to broadening of the columnar scaffold made of partially melted terminal alkyl chains. Decrease of intercolumnar interactions is also responsible for strong increase of pretranstional fluctuations in the Colh phase. The mesophase observed for longest homologues is reminiscent of relaxor phase observed for solid crystals.