Huang Tung-Liang, Chen Yung-Chung
Department of Chemical and Materials Engineering, National Kaohsiung University of Science and Technology, Kaohsiung 80778, Taiwan.
Photo-SMART (Photo-Sensitive Material Advanced Research and Technology Center), National Kaohsiung University of Science and Technology, Kaohsiung 80778, Taiwan.
Polymers (Basel). 2021 May 29;13(11):1801. doi: 10.3390/polym13111801.
Three novel visible-light absorbing benzophenone-based hydrogen acceptors (BPD-D, BPDM-D and BPDP-D) were designed on the basis of a donor-benzophenone-donor structural backbone. Mono or diketone units and double diphenylamine electron-donating groups in para-or meta-positions were introduced to comprehend the electronic and structural effects on free radical photopolymerization (FRPP). Such a structural change leads not only to a red-shift of the absorption maxima but strongly enhances their molar extinction coefficients compared to the commercial phototinitiators such as benzophenone (BP) and 4,4'-bis(diethylamino) benzophenone (EMK). In addition, excellent melting points and thermal decomposition temperatures were achieved for those novel compounds. Further, the photochemical reaction behavior was studied by cyclic voltammograms (CV), photolysis and electron spin resonance (ESR) spectroscopy. Finally, benzophenone derivatives in combination with an amine (TEA, triethylamine) as a co-initiator were prepared and initiated the FRPP of trimethylolpropane trimethacrylate (TMPTMA) using a UV lamp as a light source. When used in stoichiometric amounts, the BPDP-D/TEA had the best double bond conversion efficiency among all the compounds studied, and were even superior to the reference compounds of BP/TEA and EMK/TEA. The results and conclusions could provide the fundamental rules applicable for the structural design of benzophenone derivative-based photoinitiators.
基于供体-二苯甲酮-供体结构骨架，设计了三种新型的吸收可见光的二苯甲酮基氢受体（BPD-D、BPDM-D和BPDP-D）。引入了单酮或二酮单元以及对位或间位的双二苯胺供电子基团，以理解对自由基光聚合（FRPP）的电子和结构影响。与二苯甲酮（BP）和4,4'-双（二乙氨基）二苯甲酮（EMK）等商业光引发剂相比，这种结构变化不仅导致吸收最大值的红移，而且极大地提高了它们的摩尔消光系数。此外，这些新型化合物具有优异的熔点和热分解温度。此外，通过循环伏安图（CV）、光解和电子自旋共振（ESR）光谱研究了光化学反应行为。最后，制备了二苯甲酮衍生物与胺（TEA，三乙胺）作为共引发剂，并以紫外灯作为光源引发三羟甲基丙烷三甲基丙烯酸酯（TMPTMA）的FRPP。当以化学计量使用时，BPDP-D/TEA在所有研究的化合物中具有最佳的双键转化效率，甚至优于BP/TEA和EMK/TEA的参考化合物。这些结果和结论可为基于二苯甲酮衍生物的光引发剂的结构设计提供适用的基本规则。
