Three new amino-thioxanthone photoinitiators (PIs) with different substituents on nitrogen, including 2-allyl(methyl)amino-9H-thioxanthen-9-one (PI-1), 2-benzyl(methyl)amino-9H-thioxanthen-9-one (PI-2) and 2-butyl(methyl)amino-9H-thioxanthen-9-one (PI-3) were synthesized and characterized. They showed high molar extinction coefficients and very broad absorption range in the visible region. Among them, PI-2 showed the best visible light photoinitiating properties evidenced by the fact that it successfully initiated polymerization of 1,6-hexanedioldiacrylate (HDDA) under xenon light exposure (28 mW cm−2) both in the presence and absence of N,N-dimethylaniline (DMA) for 0.5 h with 92% and 52% conversion, respectively. For TMPTA, the conversion of PI-2 and PI-2/N-methyldiethanolamine (MDEA) systems is 32% and 62% under xenon lamp exposure for 10 min. The photoinitiation mechanisms were analysed through EPR, fluorescence spectra and visible light photolysis experiments.
合成并表征了三种氮取代基不同的新型
氨基-9H-
硫杂
蒽酮光
引发剂(
PIs),包括 2-烯丙基(甲基)
氨基-9H-
硫杂
蒽酮-9-酮(
PI-1)、2-苄基(甲基)
氨基-9H-
硫杂
蒽酮-9-酮(
PI-2)和 2-丁基(甲基)
氨基-9H-
硫杂
蒽酮-9-酮(
PI-3)。它们在可见光区域表现出很高的摩尔消光系数和很宽的吸收范围。其中,
PI-2 显示出最佳的可见光光引发特性,在
N,N-二甲基苯胺(
DMA)存在和不存在的情况下,它在
氙灯照射(28 mW cm-2)下成功引发了 1,6-hexanedioldiacrylate (
HDDA)的聚合反应 0.5 小时,转化率分别为 92% 和 52%。对于
TMPTA,在
氙灯照射 10 分钟后,
PI-2 和
PI-2/N-methyldiethanolamine (
MDEA) 系统的转化率分别为 32% 和 62%。通过 EPR、荧光光谱和可见光光解实验分析了光引发机制。