  A series of non-symmetric dimers were synthesised containing either
cyanobiphenyl or difluoroterphenyl moieties on one side and a range of long,
short, bent, polar or apolar mesogens on the other side of the molecules. The
dielectric anisotropy of the mesogens was varied systematically. The systems
were characterised by differential scanning calorimetry (DSC), optical
polarizing microscopy (OPM) and detailed X-ray diffraction (XRD) studies, both
in the nematic and the Nx phase. The results are compared and structure
properties relationships are discussed. A model for the assembly in the Nx
phase is developed discussing Ntb structures, coaxial helices, swiss roll
structures and chiral domain formation.
