Synthesis and polymerizations of (BIS)phosphonated - (BIS)methacrylamides for dental applications

Abstract

In the first part of this work, novel phosphonate and phosphonic acid-containing bis(methacrylamide)s (1 and 2) were synthesized by amidation of 2-(2-chlorocarbonyl-allyloxymethyl)-acryloylchloride with diethyl 2-aminoethylphosphonate and diethyl 1-aminomethylphosphonate. The phosphonic acid-containing monomers (1a and 2a) were synthesized by hydrolysis of 1 and 2 with trimethylsilyl bromide (TMSBr). Monomers 1 and 2 were found to have high reactivities in photo- and thermal polymerizations. In the second part of this work, two new dental monomers, one a bisphosphonate- the other a bisphosphonic acid-containing bis(methacrylamide), were synthesized. The bisphosphonate monomer (3) was synthesized by amidation of 2-(2-chlorocarbonyl-allyloxymethyl)-acryloylchloride with tetraethyl aminomethyl-bis(phosphonate) and converted to the bisphosphonic acid monomer (3a) by hydrolysis with TMSBr. Thermal polymerization of monomer 3 gave crosslinked polymers. Although monomers 1a, 2a and 3a showed very low polymerization rate and conversion, because of their good performance in terms of solubility, hydrolytic stability, hydroxyapatite (HAP) interaction, acidity and copolymerizability with HEMA, they show potential to be used in self-etching dental adhesives. Finally, two more new dental monomers, one a bisphosphonate- and a bisphosphonic acid containing methacrylamide, were synthesized. The bisphosphonate-containing monomer (4) was obtained by amidation of methacryloyl chloride with tetraethyl aminomethyl-bis(phosphonate) in the presence of triethylamine. Thermal homopolymerization of this monomer gave a soluble polymer. Photopolymerization rate of monomer 4 was found to be lower than HEMA. Hydrolysis of monomer 4 with TMSBr gave monomer 4a as a white solid soluble in water and ethanol. Although monomer 4a showed very low photopolymerization rate and conversion, addition of this monomer to HEMA increased the rate of HEMA. As a result, monomer 4a was also found to be a suitable monomer for self-etching dental adhesives.