The equation for the equilibrium between the stresses and the degree of swelling, and also for the mass balance of substrate and functional groups are proposed in order to analyze the distribution of functional groups on gelular bead. Explicit F.D.M.(finite differance method) was used to solve this equation in the case that the relaxation rate of polymer in solvent is higher than the reaction rate and diffusional rate. In the case of Thiele modulus is higher than 1, the distribution of functional groups can be controlled in polymer bead quite easily. Sulfonation of poly (styrene-co-divinylbenzene) was carried out varying degree of crosslinking under various solvent. Since effective diffusivity decreases, the extent of sulfonation decreased with degree of crosslinking. When good solvent was used and the polymer bead was expanded with functionalization, or the degree of crosslinking was low, the extent of sulfonation calculated from proposed model corresponded well with experimental results. The equation proposed can be utilized to understand the control of active functional groups distribution in the gelular polymer bead better.
