AbstractFive novel phosphonated mono‐ and dimethacrylate monomers have been synthesized by two different routes. Monomers 1 and 2 were synthesized by reactions of methacryloyl chloride with diethyl (2‐hydroxyphenyl) phosphonate or tetraethyl (2,5‐dihydroxy‐1,4‐phenylene) bisphosphonate; monomers 3 and 4 by reactions of α‐(chloromethyl)acryloyl chloride (CMAC) first with dimethyl (2‐hydroxyethyl) phosphonate and then with benzoic or formic acids. The reaction of CMAC with two moles of dimethyl (2‐hydroxyethyl) phosphonate gave monomer 5. Thermal homopolymerization of monomers 1, 3, 4, and 5 and copolymerization of monomer 1 with methyl methacrylate (MMA) were investigated using azobisisobutyronitrile (AIBN) at 60 °C. Glass transition temperatures were observed for poly‐1, poly(MMA‐co‐1) (50:50), poly(MMA‐co‐1) (90:10), PMMA, poly‐3, and poly‐5 at 52, 90, 99, 129, 50, and 70 °C, respectively. TGA analysis of these polymers indicated formation of char on combustion. Homo‐ and/or copolymerization behavior of the synthesized monomers with 2,2‐bis[4‐(2‐hydroxy‐3‐methacryloyloxy propyloxy) phenyl] propane (Bis‐GMA) were investigated with photodifferential scanning calorimetry. The maximum rate of polymerizations decreased in the following order: Bis‐GMA∼3 > 1 > 4 > 5. The conversions of monomers 1, 3, 4, and 5 (73.9, 85.9, 98.2, and 62.2%) were very high compared with Bis‐GMA (40.5%). © 2009 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 47: 5737–5746, 2009