Thermal radical polymerization of Bis(methacrylamide)s

Abstract

Methacrylamides monomers for dental applications were synthesized using a one-step procedure starting from methacrylic anhydride and the respective diamine: N,N'-(propane-1,3-diyl)-bis(N-ethyl-2-methylacrylamide) (1), N,N'(butane-1,4-diyl)-bis(2-methacrylamide) (2), N,N'-(octane-1,8-diyl-)bis(2-methylacrylamide) (3) and N,N'-(1,4-phenylene)bis(2-methylacrylamide) (4). The structures were confirmed by 1H NMR, 13C NMR, FTIR-ATR and UHPLC-QTOF-MS. Thermal polymerization kinetics was investigated by modulated DSC for monomers (2), (3) and (4) using heating rates of 1, 2, 3 and 5 °C min-1. All IR spectra showed the C=C axial deformation at 1610 cm-1, in 1H NMR spectra the olefinic hydrogens were observed at 5.3 an 5.8 ppm and in 13C NMR, the vinylic carbons at 120 and 140 ppm. The exact m/z values were: 267.2068, 225.1595, 281.2222 and 245.1283 for monomers (1), (2), (3) and (4), respectively. The activation energy was: -182.7; -165.8 and -156.7 kJ mol-1 for monomers (2), (3) and (4), respectively. Monomers are promising candidates for use as hydrolytic stable adhesive systems for dental applications.