Microscopy studies of the nematic N_TBphase of 1,11-di-(1′′-cyanobiphenyl-4-yl)undecane

A detailed microscopy study of the mesophases of 1,11-di-(1′′-cyanobiphenyl-4-yl)undecane (CB11CB) was undertaken, with an emphasis on attempting to relate the recent helical “twist-bend” model of the NTB phase to the observed optical textures. Our ability to draw a freestanding film indicates that the phase is unlikely to be nematic and possesses long range periodicity. No electrooptic response could be detected in the NTB phase, with or without addition of a chiral dopant although dielectric breakdown and space charge were observed at high voltage leading to field dependent pulsing of the sample. No optical rotation associated with a macroscopic helical structure could be discerned in the NTB phase. However, this observation could be taken to be in keeping with the extremely short pitch of a proposed “twist-bend” model.