Synthesis and evaluation of ethylene glycol 3-diethylamino-propionate methacrylate as a polymerizable amine coinitiator for dental application

Objective The primary objective of this study was to synthesize and characterize ethylene glycol 3-diethylamino-propionate methacrylate (EGDPM) as a polymerizable coinitiator to replace the commercial amine coinitiator. The 2,2-bis[4-(2-hydroxy-3-methacryloxypropoxy)phenyl]-propane (Bis-GMA) and triethylene glycol dimethylacrylate (TEGDMA) resin mixture was polymerized by camphorquinone/EGDPM initiator system under visible light irradiation. The mechanical properties, water sorption and solubility of cured samples were also evaluated. Methods EGDPM was synthesized via Michael-Addition reaction and characterized using FTIR and 1H NMR spectroscopy. Photopolymerization kinetics of the dental resin mixtures were monitored by real-time IR (RTIR). The mechanical properties of cured samples were recorded by dynamic mechanical analyzer (DMA). And the water sorption and solubility of cured samples were detected according to ISO 4049. Results Both the double bond conversion and the rate of polymerization of the resin mixtures increased as increasing the concentration of EGDPM but were lower than that of ethyl-4-dimethylaminobenzoate (EDMAB) and 2-(dimethylamine)ethyl methacrylate (DMEM) as a coinitiator at some concentration. When it served as diluent, the final double bond conversion was comparable to that of EDMAB, and the rate of polymerization was higher than that of DMEM. The modulus and Tg of the cured samples were very close. Water sorption and solubility of the samples were almost the same except that of EGDPM as diluent. Conclusions EGDPM was synthesized by Michael-Addition reaction. It could be used as a potential coinitiator but not suitable as diluent for dental composite.