Abstract
ABSTRACTThe synthesis of polymerizable 7-(methacroyloxy)-2-oxo-heptylphosphonic acid M1 destined for self-etch adhesives is described. M1 is characterized by 1H, 13C and 31P-NMR spectroscopy. Its homopolymerization and copolymerization reactivity in the solvents methanol and dioxane between 45 and 70°C in the presence of azobisisobutyronitrile (AIBN) are examined. Polymerization proceeds readily through a thermal free radical initiation. The intensity exponents for the monomer and initiator are only slightly over 1 and approximately 0.5, respectively. This is in accordance with the results typically observed for an ideal free radical polymerization with termination mainly by disproportionation, which is typical for methyl methacrylate (MMA) homopolymerization. The kinetics of copolymerization with MMA are monitored by online 1H-NMR spectroscopy. Two copolymerization reactions for each pair of co-monomers are sufficient to evaluate the copolymerization parameters using the Jaacks method, the Fineman–Ross method and the nonlinear least-squares method. All three methods give similar results for particular monomer M1/MMA couple.
Highlights
Composite restorative materials represent success of modern biomaterials research since they replace biological tissue in both appearance and function [1]
Such derivatives are potentially interesting as the incorporation of a phosphonic or phophoric acid function would result in an increase of the biocompatibility and in the adhesion due to ionic interaction with calcium ions at the tooth surface [4] because of complex formation with calcium in hydroxyapatite [5]
The acidic monomer M1 was prepared in three steps, starting from diethyl methylphosphonate (Scheme 2)
Summary
Composite restorative materials represent success of modern biomaterials research since they replace biological tissue in both appearance and function [1]. Self-etching adhesive developed for bonding of resin composite to enamel and dentin, containing phosphonic acid or dihydrogenphosphate groups have been quite widely considered [4,5,6,7,8]. Such derivatives are potentially interesting as the incorporation of a phosphonic or phophoric acid function would result in an increase of the biocompatibility and in the adhesion due to ionic interaction with calcium ions at the tooth surface [4] because of complex formation with calcium in hydroxyapatite [5]. The structure of given monomer M1 is shown on Scheme 1
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