Abstract The present work provides a comparative study on the photoreactivity of nano-sized silica particles bearing different types and amounts of photocleavable species as organic shell. Newly synthesized trialkoxysilyl-functionalized bis(acyl)phosphane oxide and aromatic α-hydroxyketone derivatives, which efficiently undergo Norrish type I photofragmentation reactions, are immobilized on the surface of nanosilica by using convenient silanization techniques. Qualitative and quantitative characterization of the immobilized species is carried out by spectroscopic measurements and thermal gravimetric analysis. In dependence on the reaction conditions, particles with varying amount of photoactive groups are obtained. The influence of the degree of modification on the initiation efficiency in the radical mediated thiol-ene photopolymerization is determined. It is shown that in thin films the curing rates are influenced by the employed grafting method. As an approach towards low extractable photoinitiators, the migration of the immobilized photoinitiators was evaluated by Soxhlet extraction. Elemental analysis of the extracts evidenced that the extractable content of particles with a high degree of modification is below the detection limit of the method.

中文翻译：

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光活性二氧化硅纳米粒子：表面官能化对自由基诱导光聚合反应迁移和动力学的影响

摘要 目前的工作提供了具有不同类型和数量的光可裂解物质作为有机壳的纳米二氧化硅颗粒的光反应性的比较研究。新合成的三烷氧基甲硅烷基官能化双（酰基）氧化膦和芳香族 α-羟基酮衍生物可有效地进行 Norrish I 型光碎反应，通过使用方便的硅烷化技术固定在纳米二氧化硅表面。固定物质的定性和定量表征是通过光谱测量和热重分析进行的。根据反应条件，获得具有不同数量光活性基团的颗粒。确定了改性程度对自由基介导的硫醇-烯光聚合引发效率的影响。结果表明，在薄膜中固化速率受所采用的接枝方法的影响。作为一种解决低可萃取光引发剂的方法，通过索氏萃取评估了固定化光引发剂的迁移。提取物的元素分析表明，高度修饰的颗粒的可提取含量低于该方法的检测限。