Novel methacrylate monomers bearing phosphonic acid groups 1 and 2 as well as new sulfur methacrylates 9 and 10 have been prepared in good yields from thiophenol. They have been fully characterized by H-1-NMR, C-13-NMR, P-31-NMR, and HRMS. Their copolymerization with a bis-GMA : TEGDMA (1 : 1) blend has been investigated with photodifferential scanning calorimetry at 50 degrees C with camphorquinone as a photoinitiator and ethyl 4-(dimethylamino)benzoate (EDAB) as a coinitiator. The higher the content of acidic monomer 1 or 2 incorporated in the bis-GMA : TEGDMA (1 : 1) blend, the lower the mixtures reactivity. The phosphonic acid group has been proved to be responsible for this drop of reactivity. (C) 2010 Wiley Periodicals, Inc. J Appl Polym Sci 117: 2676-2687, 2010