The preparation of imidazole-functionalized latex microspheres by a two-stage emulsion copolymerization process and their characterization are reported on. Emulsifier-free emulsion copolymerization of styrene (St) and 1-vinyl imidazole (VIMZ) exhibited bimodal particle size distributions caused by secondary homogeneous nucleation process. However, secondary nucleation can be avoided by using cetyltrimethylammonium bromide (CTAB) as a stabilizer at a concentration below its cmc (critical micelle concentration). This would result in the formation of monodisperse latex particles. The final particle size diameter depended on the concentration of CTAB as well as the amount of VIMZ. To control the amount of the functional imifidazole groups on the latex particle surfaces, independent of the latex diameters, without secondary nucleation of particles, the seeded emulsion copolymerization of styrene and VIMZ was explored as a secondstage polymerization at different concentrations and ratios of monomers in the presence of the previously prepared monodisperse poly(styrene-co-1-vinyl imidazole) seed latex particles. The concentration of imidazole functional groups on the surface of the latex particles could also be varied through the rearrangement of hydrophilic imidazole groups by varying the second-stage monomer addition process such as the utilization of monomer-swollen seed particles or a shot addition of monomers. (c) 2006 Wiley Periodicals, Inc.