Synthesis and characterization of new Schiff base ester liquid crystals with fatty acids from palm oil as flexible alkyl chain

Palm oil plays an important role in both food and non-food industries. With the aim of further diversifying the non-food applications of palm oil, the viability of using palm fatty acids in the synthesis of liquid crystals (LCs) has been investigated. In this study, three types of palm fatty acid, namely lauric acid, palmitic acid and stearic acid were used as a source of flexible alkyl chain, which is an influential structural feature of LCs. This flexible alkyl chain is usually derived from non-renewable petrochemicals. Three palm-based LCs (PBLCs), namely, PB₁ (lauric-based LC), PB₂ (palmitic-based LC) and PB₃ (stearic-based LC) have been synthesized and the presence of liquid crystallinity was further verified by Polarizing Optical Microscopy (POM), Differential Scanning Calorimetry (DSC) and Wide Angle X-ray Diffraction (WAXD). Mesophase was observed from POM analysis for PB₁-PB₃ and based on the scattering pattern of WAXD at small angle region, the texture of the mesophase was Smectic A phase. The synthesized PBLCs can be potential candidate for various practical applications such as engineering of nanostructure and biomaterials due to the presence of curvatures which is a unique characteristic of smectic LCs. This study can be regarded as a continuous effort in realizing the concept of green chemistry by using non-toxic and renewable feedstock in organic synthesis.