Synthesis of ferroelectric liquid-crystalline polymethacrylates containing 1,2-diphenylethane based mesogens

Abstract

The synthesis of side-chain liquid-crystalline polymethacrylates containing (2S)-2-chloro-4-methylvaleric acid end groups and 1,2-diphenylethane based mesogenic units is presented. Differential scanning calorimetry, optical polarizing microscopy and X-ray diffraction were used to determine the thermal transitions and to analyze the anisotropic phases. Among the methacrylate monomers prepared in this study, those without lateral chloro substituent show only a smetic A phase while those with a lateral chloro substituent display a cholesteric phase. All polymers exhibit smectic mesomorphism and do not undergo side-chain crystallization. All four polymethacrylates without lateral chloro substituents reveal enantiotropic smectic A and smectic B phases while the other four polymethacrylates with lateral chloro substituents reveal enantiotropic smectic A and chiral smectic C phases. The results seem to demonstrate that incorporating a lateral chloro substituent into the mesogenic core enhances the formation of a tilted chiral smectic C phase.