Acrylonitrile/ammonium itaconate [AN/ (NH4)(2)IA] aqueous deposited polymerizations were studied in this work. It shows that the polymerizations were influenced by various factors, especially the water solubility of AN. In the polymerization process, the system was as separated monomer and water phases, and AN transferred from monomer phase to water phase until the monomer phase disappeared. Because of the solubility of AN in water, the reactivity ratios of monomer calculated by Kelen-Tudos method were different in various monomer contents. Although (NH4)(2)S2O8 was a water-soluble initiator, there was a short amount of polymer formed in monomer phase. To inhibit the polymerization in monomer phase, two additives were used in the polymerization and experiment data indicated that the two inhibitors exert inhibitory role effectively in monomer phase. (c) 2006 Wiley Periodicals, Inc.