Structure-property relationship of a series of novel mesogen-jacketed liquid-crystalline polymers containing semirigid side chain with different numbers of alkoxy terminal groups

A series of vinyl monomers, 2, 5-bis (4-methoxy benzyl) oxycarbonyl] styrene (MBCS); 2, 5-bis (3, 5-dimethoxy benzyl) oxycarbonyl] styrene (DMBCS) and 2, 5-bis (3, 4, 5-trimethoxy benzyl) oxycarbonyl] styrene (TMBCS) were synthesized and polymerized via free radical polymerization. The terminal groups of the semirigid side chain were systematically varied to investigate the effects of their numbers on the ability of mesophase formation of the resultant polymers. The chemical structures of the monomers were confirmed by elemental analysis, ¹H NMR and ¹³C NMR. The characterization of the polymers was performed with ¹H NMR, gel permeation chromatography (GPC). The phase structures and transition behaviors were studied using differential scanning calorimetry (DSC), polarized light microscopy (PLM) and one- and two-dimensional wide-angle X-ray diffraction (WAXD). The experimental results suggested that the ability of mesophase formation of the polymers decreased as the rigidity of side-chain group decreased and increased as the number of the alkoxy terminal group increased, and that all the polymers with high molecular weight showed stable columnar nematic phase (Φ_N).