Synthesis and polymerizations of phosphonated-bis(methacrylamide)s for dental applications

Novel phosphonate and phosphonic acid-containing bis(methacrylamide)s were synthesized. The phosphonate-containing monomers (1a and 1b) were synthesized by amidation of 2-(2-chlorocarbonyl-allyloxymethyl)-acryloylchloride with diethyl 2-aminoethylphosphonate and diethyl 1-aminomethylphosphonate. The phosphonic acid-containing monomers (2a and 2b) were synthesized by hydrolysis of 1a and 1b with trimethylsilyl bromide (TMSBr). All monomers were liquids and dissolved in water and ethanol. Thermal homopolymerization of 1a and 1b in bulk and solution using 2,2'-azobis(isobutyronitrile) (AIBN) at 80 degrees C gave crosslinked polymers indicating low cyclization tendencies of these monomers. They were also homopolymerized using photo-DSC with 2,2'-dimethoxy-2-phenyl acetophenone (DMPA) as photoinitator, and their maximum rates of polymerization were found to be higher than commercial monomers 2,2-bis[4-(2-hydroxy-3-methacryloyloxy propyloxy) phenyl] propane (Bis-GMA) and 2-hydroxyethyl methacrylate (HEMA), indicating their potential as reactive diluents or crosslinkers in dental materials. In fact, copolymerization with monomer 1a resulted in improvements in photopolymerization kinetics of both Bis-GMA and HEMA. The acidic nature of the aqueous solutions (pH of 2a: 1.42, 2b: 1.53), stability under aqueous conditions after 1 month of study at 37 degrees C, interaction of 2a with hydroxyapatite (HAP) as representative of both monomers, and copolymerizability of the same with HEMA make these monomers suitable as adhesive monomers in dental adhesives, although their low observed reactivities may present a drawback. (c) 2011 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 50: 801-810,, 2012