New aromatic tert-amines for application as photoinitiator components in photocurable dental materials

A new type of aromatic tert-amine with a bisphenol-A (BPA) skeleton has been prepared and applied as a photoinitiator (PI) component for enhancing photosensitivity in formulations of visible light curable dental polymers. Two N,N-dimethylamino (DMA) groups were incorporated into BPA diglycidyl ether to make 2,2-bis[4-(2-hydroxy-3-(p-N,N- dimethylaminobenzoyloxy)propyloxy)phenyl]propane (DMABPA). One or two (meth)acryloyl groups were reacted with the hydroxyl groups of DMABPA to obtain the polymerizable, BPA-based tert-amines. DMABPA-1M (one-methacrylate), DMABPA-2M (two methacrylates), and DMABPA-1A (one acrylate). The aromatic tert-amines and ethyl p-(N,N-dimethlamino)benzoate(EDMAB) were combined with a camphorquinone sensitizer to for a photoinitiating system, which was applied in photopolymerizations of dental resin formulations, based on Bis-GMA as a matrix prepolymer, by visible light exposure. The photoconversion of the formulations using the new aromatic tert-amines as PIs was determined by the spectral changes in FTIR absorption intensities of methacrylate groups in cast films. High conversion (over 70%) resulted from photopolymerizations with (meth)acrylated DMABPA-(1M,2M, and 1A).