Janus-Type Dendromesogens: A Tool to Control the Nanosegregation and Polar Organization of Bent-Core Structures

Several first- or second-generation Janus-type codendrimers that combine promesogenic bent-core and rodlike molecular segments have been synthesized by the versatile CuAAC reaction and the materials have been characterized by POM, DSC, XRD, and SHG studies. Depending on the ratio between the number of rod- and bent-core units, these compounds form mesophases ranging from nematic to a complex polar smectic mesophase in which the two types of mesogenic moieties are segregated on a nanometric scale. In the case of a 1:1 bent/rod ratio, the materials form ferroelectric mesophases and the macroscopic polarization is stable in the absence of an applied electric field. The appearance of the different mesophases is explained in terms of the relative values of the transverse areas of the mesogenic cores.