Ethyl‐4‐(Dimethylamino) benzoate initiation of the spontaneous polymerization of aqueous acidic adhesive formulations in the presence of a base

This study indicated that the spontaneous polymerization of an aqueous acidic dental adhesive system containing ethyl-4-(dimethylamino) benzoate (4E) could be activated by various bases. The adhesive was prepared with a monomer mixture of bis[2-(methacryloyloxy)ethyl] phosphate (2MP) and 2-hydroxyethyl methacrylate (HEMA). Various amounts of base [hydroxyapatite (HAP) and its analogues, e.g., Ca(OH)2, NaOH, and calcium carbonate] were added. Real-time Fourier transform infrared–attenuated total reflectance spectroscopy was used to monitor the polymerization process. The pH and buffer capacity affected the degree of conversion, and the polymerization rate and induction period were evaluated. The optimal conditions for the pH of this system was between 1.0 and 1.8, and HAP had the best performance on polymerization because of its excellent buffer capacity. The mechanism for the spontaneous polymerization of the 2MP/HEMA adhesive system was proposed with 4E as an initiator. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 130: 2698–2706, 2013