Photoinitiating Ability of Pyrene–Chalcone‐Based Oxime Esters with Different Substituents

Abstract

AbstractWith the rapid development of new irradiation setups as well as the ongoing interest in 3D printing, photopolymerization is extensively studied during the last decades. In photopolymerization, a photoinitiator and/or photosensitizer play(s) a crucial role in the photoinitiation step as this component absorbs light, thus creating the initiating species. In this study, a series of 17 chalcone‐based oxime esters (OXEs) featuring the pyrene chromophore are designed, synthesized, and studied for their photoinitiation properties upon irradiation with visible light. Precisely, their photoinitiation abilities are examined during the free radical photopolymerization of acrylates under the irradiation of light‐emitting diode (LED) at 405 nm. In the series of oxime esters, five of them demonstrate excellent photoinitiation abilities. Their thermal initiation abilities are also examined. To improve their photoinitiation abilities, these type I photoinitiators are also tested as type II photoinitiators in two‐component photoinitiating systems using bis‐(4‐tert‐butylphenyl)iodonium or ethyl 4‐(dimethylamino)benzoate as additives. In this process, the OXE‐B/iodonium system shows the best photopolymerization. To develop the use of these chalcone‐based oxime esters, the best OXE is used as a monocomponent photoinitiating system in 2D laser writing at 405 nm. The design of composites using glass fibers or carbon fiber as fillers is also examined.