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R. Liska:
"Advanced techniques for Photocuring of Hydrogels";
Vortrag: 4th European Symposium of Photopolymer Science, Leipzig (eingeladen); 11.09.2016 - 14.09.2016; in: "ESPS 2016", (2016), S. IL-3.

Photopolymerizable hydrogels have gained increasing interest in recent years, especially for the use in the biomedical field. Surprisingly, there are only a small number of water-soluble initiators on the market. Salts of mono- and bisacylphosphine oxides are here interesting alternatives due to their high solubility and their absorption in the visible range of the spectrum.

Frontal photopolymerization is an energy efficient method for the preparation of bulk cured materials by light triggered reactions. Due to the high heat of polymerization, bubble free polymerization of aqueous hydrogel formulations is up to now an unsolved problem. With appropriate thermal initiators a suitable processing window can be found.

In the last decade there has also been a strong demand for printing arbitrarily shaped 3D cellular structures by additive manufacturing technology (AMT). Multi photon photopolymerization is here an advanced AMT technique that allows a real 3D writing of photopolymerizable formulations with feature resolutions well below 1 µm. For biomedical applications, acrylate-based monomers are undesirable due to their high irritancy and cytotoxicity. Vinylesters and vinylcarbonates represent an appealing class of photopolymers with exceptionally low cytotoxicity and suitable photoreactivity. Degradation can be easily tuned giving non-toxic low molecular polyvinyl alcohol as degradation product. Using suitable monomers based on gelatin and hyaluronic acid and specially designed photoinitiators we were able to cure hydrogels with a femtosecond pulsed laser in the presence of cells.

Photopolymerizable hydrogels, Frontal photopolymerization, biomedical applications