Liquid-crystalline monomer cholesteryl 4-allyloxybenzoate (M-1), new ionic mesogenic monomer cholesteryl 4-allyloxy-3-(potassium sulfonate)benzoate (M-2), and corresponding polymer P-1 and ionomer P-2 were synthesized. The chemical structures of the monomers and homopolymer were confirmed with Fourier transform infrared and H-1-NMR spectroscopy. The mesogenic properties were studied with differential scanning calorimetry, thermogravimetric analysis, polarizing optical microscopy, and X-ray diffraction measurements. The effect of the ionic units on the phase behavior was examined. M, showed a cholesteric phase, and M-2 revealed a smectic A phase. P-1 and P-2 displayed smectic A phases. The experimental results demonstrated that the addition of ionic units to the mesogenic molecule not only affected the phase-transition temperature but also changed the inesogenic phase type. (C) 2004 Wiley Periodicals, Inc.