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, H-1 NMR and C-13 NMR. The characterization of the polymers was performed with H-1 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 (Phi(N)). (C) 2009 Elsevier Ltd. All rights reserved.