Design of new phenothiazine derivatives as visible light photoinitiators
In an actual article, four new phenothiazine derivatives (denoted as PT1, PT2, PT3 and PT4) are specifically in silico designed by molecular modelling for good light absorption properties @405 nm.
Two of the proposed structures from this in silico design were never synthesised prior to this work. Image source: mohamed Hassan - Pixabay.
-The most interesting structures showing both intense violet/blue light absorption and high potential photochemical reactivity were synthesised for detailed investigations as photoinitiators/photosensitisers in the presence of an iodonium salt for the free radical photopolymerisation of (meth)acrylates and the cationic polymerisation of epoxides upon near-UV or visible light irradiation.
Excellent polymerisation rates and high final reactive function conversions
Remarkably, two of the proposed structures (PT3 and PT4) from this in silico design were never synthesised prior to this work and were thus specifically designed for this work. Three-component photoinitiating systems based on PT/iodonium/amine (N-phenylglycine or ethyl 4-dimethylaminobenzoate) are also developed for the free radical polymerisation of acrylates. Both excellent polymerisation rates and high final reactive function conversions were obtained.
The picture of the photochemical mechanisms was provided using different techniques: real-time Fourier transform infrared spectroscopy, UV-visible spectroscopy, fluorescence spectroscopy, and cyclic voltammetry. Finally, the high performance of the phenothiazine derivatives is also shown in 3D printing experiments as well as in photocomposite synthesis using glass fibres (thick sample; using a LED@395 nm conveyor).
The study has been published in Polymer Chemistry, Issue 19, 2020.
