Abstract
ABSTRACT We report the synthesis and the temperature dependencies of optical, dielectric, and elastic properties of four homologous dimeric mesogens in the uniaxial nematic (N) phase. The studied dimers are derived from 2ʹ,3ʹ-difluoroterphenyl units connected via flexible alkyl chains. The compounds differ in the length of either the flexible alkyl chain or the terminal groups. These achiral bimesogens exhibit the twist-bend nematic (NTB) phase with a nanoscale pitch of the modulated nematic director, as established by the freeze-fracture transmission electron microscopy. All four homologs have negative dielectric anisotropy owing to the permanent dipole oriented normal to the long molecular axes. A longer flexible bridge length yields an expanded temperature range of the N phase, stronger dielectric anisotropy, larger birefringence and bend elastic constant . Longer alkyl terminal chains increase birefringence but decrease the absolute value of dielectric anisotropy and . All four bimesogens show a dramatic decrease of down to ~0.5 pN on approaching the N-NTB transition. A longer bridge yields a longer period of twist-bend modulation in the NTB phase.
Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
