Synthesis, phase transition behaviour and dielectric properties of smectogenic palm-based liquid crystals containing schiff base ester and phenyl ring

Abstract

Smectogenic liquid crystals (LCs) play an important role in various technological applications due to their interesting morphologies and defects. With incessant effort to add value to palm oil, another two series of palm-based liquid crystals (PBLCs), namely PB1a-PB3a and PB1b-PB3b, utilizing palm fatty acids as flexible alkyl chain have been synthesized. The appearance of smectic A phase for all PBLCs was authenticated by Polarizing Optical Microscopy (POM) and further verified by Differential Scanning Calorimetry (DSC) and Small Angle X-ray Scattering (SAXS). Results revealed that the mesophase range of all synthesized LCs is highly dependent on flexible alkyl chain length, the presence of polar terminal substituent as well as the breath to width ratio of mesogenic core. Dielectric measurements show that the dielectric strength is also affected by the length of the flexible alkyl chain. It is worth noting that, as far as mesophase range is concerned, PBLCs were found to be far superior over other structurally related compounds that can be found in the literature.