UV/Vis-LED激发的香豆素吡啶鎓盐光引发剂的合成及性能

设计合成了3种基于香豆素骨架的紫外-可见发光二极管(UV/Vis-LED)可激发的新型吡啶鎓盐光引发剂, 并研究了这3种香豆素吡啶鎓盐的构效关系及其作为单组分自由基光引发剂在丙烯酸酯体系中的光引发活性. 紫外-可见吸收光谱分析表明, 这3种香豆素吡啶鎓盐在300~400 nm区域有较强吸收. 在LED@365 nm和LED@405 nm光源辐照下, 研究了3种光引发剂的稳态光解和光聚合动力学. 研究表明, 这3种香豆素吡啶鎓盐光引发剂在相应光辐照下都具有较好的光解速率. 此外, 3种光引发剂对丙烯酸酯都具有较好的引发活性. 构效关系研究表明, 吡啶环4号位引入推电子的甲氧基会使其引发丙烯酸酯单体聚合的活性降低; 而引入吸电子的乙酰基会使其引发丙烯酸酯单体聚合的活性增加. 差示扫描量热(DSC)实验表明, 此类吡啶鎓盐光引发剂具有较好的热稳定性. 当3种光引发剂与丙烯酸单体混合时可提升体系的热稳定性; 通过电子自旋共振(ESR)证明了活性物种的产生, 并对该类引发剂的引发机理进行了探讨.

Synthesis and Properties of UV/Vis-LED Excitable Photoinitiators Based on Coumarin Pyridinium Salt

Three novel pyridinium salt photoinitiators（PIs）， which can be excited by ultraviolet/visible light emitting diode（UV/Vis-LED）， based on coumarin framework were designed and synthesized， and their structure- activity relationship and photoinitiation activities as one-component radical photocuring initiators in acrylate system were studied. UV-Vis absorption spectra showed that the three PIs have strong absorption in the region of 300—400 nm. The steady-state photolysis and photopolymerization kinetics of three PIs were studied under the irradiation of LED@365 nm and LED@405 nm light sources. The results indicated that the three PIs all demonstrate good photolysis rate and excellent initiation activity for acrylates. Through the study of structure-activity relationship， it is found that when the electron-pushing methoxy group is introduced into the para-position of the pyridine ring， the activity of initiating the polymerization of acrylate monomers will decrease； meanwhile， the activity will increase while the electron-withdrawing acetyl group is introduced into the para-position of the pyridine ring. Differential scanning calorimetry（DSC） experiments indicated that the three pyridinium onium salt photoinitiators all demonstrate excellent thermal stability. It is interesting that when PIs were mixed with acrylic monomers， the thermal stability of the system can be improved. The generation of active species was proved by electron spin resonance（ESR） and the initiation mechanism of the initiator was discussed.