Visible light and water-soluble photoinitiating system based on the charge transfer complex for free radical photopolymerization

Abstract Visible light and water-soluble photoinitiator is of great significance in the field of photopolymerization, especially for the fabrication of hydrogel or 3D printing. Photoinitiator with the characters of water-soluble and visible light represents the important advances in the field of hydrogel preparation. However, most of photoinitiator is not water soluble. In this work, electron transfer complex(CTC) photoinitiating system formed by water-insoluble photoinitiator (2E,6E)-2,6-bis(furan-2-ylmethylidene) cyclohexan-1-one(BFC)(electron acceptor) and water-soluble coinitiator triethanolamine(TEOA)(electron donor) for free radical photopolymerization was reported and characterized by molecular orbital calculations(MOC) theoretically and UV-vis, fluorescence spectroscopy analysis experimentally. Based on the strong CTC effect, not only [BFC-TEOA]CTC exhibited an extended absorption in the visible light region, but also [BFC-TEOA]CTC performed enhanced water-solubility. Photopolymerization kinetics proved [BFC-TEOA]CTC at the concentration of 2 wt% could initiate polymerization of waterborne monomer AM rapidly and effectively in water. This facial method especially converting water-insoluble photoinitiator into water-soluble photoinitiating system via CTC was convenient and low-cost, could be potential for photopolymerization.