Recently, visible-light polymerization has received increasing attention because of the development of LED sources and the innovation of photopolymerization technology, which is derived from different strategies to design photoinitiating systems such as the construction of D-π-A-type photoinitiators or the use of up-conversion nanoparticles. However, the association of electron donor and acceptor molecules to form a charge-transfer complex (CTC) for polymerization has rarely been reported. Hence, a ketoxime ester (PFO) with a pentafluorophenone ring as an electron-defect acceptor has been designed and synthesized as a photosensitizer. Our investigation results showed that CTCs could be formed by associating PFO with amines that contain electron-rich rings and process a better absorption property in the visible-light region than PFO. Moreover, the two kinds of free radicals with high photoactivity were generated from CTCs via photochemical transformation, such as intermolecular charge transfer and α-cleavage, which can play a role in initiating the polymerization of acrylate monomers, and the efficiency of initiating polymerization is higher than that of PFO alone under LED@395–425 nm irradiation.

中文翻译：

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基于电荷转移复合物的新型酮肟酯胺光引发剂用于自由基 LED 聚合


近年来，由于LED光源的发展和光聚合技术的创新，可见光聚合受到越来越多的关注，这源于设计光引发系统的不同策略，例如构建D-π-A型光引发剂或使用上转换纳米粒子。然而，电子供体和受体分子缔合形成用于聚合的电荷转移复合物（CTC）的报道却很少。因此，设计并合成了具有五氟苯酮环作为电子缺陷受体的酮肟酯（PFO）作为光敏剂。我们的研究结果表明，CTC 可以通过 PFO 与含有富电子环的胺缔合而形成，并且在可见光区域比 PFO 具有更好的吸收性能。而且CTCs通过分子间电荷转移、α-裂解等光化学转化产生两种具有高光活性的自由基，能够起到引发丙烯酸酯单体聚合的作用，引发聚合效率较高与单独使用 PFO 在 LED@395–425 nm 照射下的结果相比。