: 2,2-Bis[4-(2-hydroxy-3-methacryloxypropoxy) phenyl]-propane (bis-GMA), triethylene glycol dimethylacrylate (TEGDMA), camphorquinone (CQ), ethyl-4-dimethylaminobenzoate (EDMAB), or 2-(dimethylamine)ethyl methacrylate (DMEM) were composed of the modern dental composite system and acted as resin, diluent, photoinitiator, and coinitiator, respectively. In this study, ethylene glycol 3-morpholine-propionate methacrylate (EGMPM) was synthesized via Michael addition reaction to replace both the TEGDMA as a diluent and the nonpolymerizable amine EDMAB as a coinitiator. Mixtures of bis-GMA/TEGDMA/CQ/EGMPM and bis-GMA/TEGDMA/CQ/DMEM were found to have almost the same rate of polymerization and reach final double bond conversion at 58%, slightly lower than that of the bis-GMA/ TEGDMA/CQ/EDMAB (63%) and bis-GMA/EGMPM/CQ (60%) under comparable visible light irradiation conditions. In addition, the results of dynamic mechanical analysis showed that all of the four samples had approximately the same modulus and the glass transition temperature. The water sorption and solubility of bis-GMA/TEGDMA/CQ with different amines (EDMAB, DMEM, and EGMPM) had almost the same value except that the water sorption of bisGMA/EGMPM/CQ was out of the range of the ISO 4049 (2000) standards. The results indicated that EGMPM was potentially a coinitiator for dental composite, because there are no significant differences in photopolymerization characteristic and physical properties when compared with traditional system (bis-GMA/TEGDMA/CQ/EDMAB). (c) 2006 Wiley Periodicals, Inc.