【摘要】 制备了6种不同结构的二芳基碘鎓盐。通过近红外光谱测定环氧树脂(E-51)在碘鎓盐引发下的环氧转换率,系统考察了在395 nm LED光源辐照下,取代基对二芳基碘鎓盐引发E-51光聚合的影响。通过密度泛函理论对合成的6种碘鎓盐进行分子优化,发现不同的取代基对二芳基碘鎓盐的最低未占分子轨道能级和最高占据分子轨道能级均会产生影响。电化学测试发现,取代基通过对碘鎓盐的还原电势产生影响,进而影响其与光敏剂间的光电荷转移能力。根据Rehm-Weller公式,计算得到了不同取代基的碘鎓盐与异丙基蒽酮间电荷转移的自由能,它们之间的自由能变化值分别为-1.017、-0.720、-0.664、-0.577、-1.140和-0.915 e V,从热力学上讨论了电荷转移的可能性。研究发现不同烷基取代基的碘鎓盐中,烷基空间位阻越小,其光引发速率越快;当碘鎓盐芳环上连接吸电子基团时,光引发速率提高。更多还原

【Abstract】 Six diaryliodonium salts with different structures were prepared. The conversion rate of epoxy resin(E-51) initiated by iodonium salt was determined via near-infrared spectroscopy. The effects of the substituents on the photocuring of E-51 induced by diaryliodonium salts, under a 395 nm LED light source, were investigated systematically. Molecular optimization of the six iodonium salts, as studied using the density functional theory, showed that the substituents had different effects on the LUMO(lowest unoccupied molecular orbital) and HOMO(highest occupied molecular orbital) energy levels of the diaryliodonium salts. Electrochemical experiments revealed that the substituents influenced the reduction potentials of the iodonium salts, and thus, affected the photoinduced charge transfer ability with the sensitizer. The free energy for charge transfer between the iodonium salts with different substituents and the isopropyl thioxanthones were calculated using the Rehm-Weller formula. The free energy changes were found to be-1.017,-0.720,-0.664,-0.577,-1.140, and-0.915 e V, and the possibility of charge transfer was discussed thermodynamically. In the case of the iodonium salts with different alkyl substituents, the smaller the steric hindrance of the alkyl group, the larger was the photoinitiation rate. The electron-withdrawing groups attached to the aromatic ring of the iodonium salts were found to further increase the photoinitiation rate.更多还原