[Zurück]

M. Mitterbauer, P. Knaack, S. Naumov, M. Markovic, A. Ovsianikov, N. Moszner, R. Liska:
"A novel highly reactive Sn-based Type I photoinitiator with excellent photobleaching behavior for long wavelength curing applications";
Poster: 5th European Symposium of Photopolymer Science, Mulhouse, France; 03.09.2018 - 06.09.2018; in: "5th European Symposium of Photopolymer Science", 5th European Symposium of Photopolymer Science, (2018), S. P28.

Recently, the scope of visible light-induced photopolymerization was largely expanded by the development of advanced applications like curing of dental composites or lithography-based ceramic manufacturing.1 To achieve sufficient curing depths in such filled systems, highly reactive photoinitiators, which show absorption in the visible range are of great interest. Type II photoinitiators offer potential within this area, but suffer from lower reactivities due to the bimolecular mechanisms of radical formation and often reveal poor photobleaching behavior. Current state of the art Type I initiators circumvent these problems, but usually show very low photoinitiating activity upon exposure with light of wavelengths above 500 nm.
Within this work, we present tetrakis(2,4,6-trimethylbenzoyl)stannane as a novel acylstannane-based photoinitiator2,3 for visible light radical photopolymerizations. When compared to state-of-the-art Germanium-based photoinitiators,4,5 it shows outstanding photochemical properties like high reactivity towards (meth)acrylate double bonds and fast photobleaching. Additionally, it reveals huge benefits particularly at irradiation wavelengths above 500 nm. In contrast to known acylgermanes, tetrakis(2,4,6-trimethylbenzoyl)stannane can be used to initiate polymerizations upon green light exposure (522 nm LED, 532 nm laser), which makes higher curing depths in highly filled systems possible. Furthermore, unlike many tin organyls, the novel photoinitiator and its photoproducts show surprisingly low cytotoxicity.