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J. Steindl, T. Koch, N. Moszner, C. Gorsche:
"Silanes as promising chain transfer agents for vinyl ester-based photopolymer networks";
Poster: 5th European Symposium of Photopolymer Science, Mulhouse, France; 2018-09-03 - 2018-09-06; in: "5th European Symposium of Photopolymer Science", 5th European Symposium of Photopolymer Science, (2018), P45.

Photopolymers are an important class of materials in applications ranging from protective and decorative coatings to more advanced fields such as 3D-printing. State-of-the-art formulations are based on acrylic monomers, but they suffer from significant toxicity, which makes their utilisation in the field of biomedicine difficult. Therefore, vinyl esters are an interesting alternative monomer moiety for these materials.1 However, they exhibit low monomer reactivity and give very inhomogeneous networks, which lead to high shrinkage stress during polymerisation and insufficiently cured, brittle materials. Thus, a desire is given for additives, which enhance the reactivity but also act as network modifier to improve material performance.2
A popular approach to overcome these drawbacks is to apply chain transfer agents (CTAs). They change the polymerisation mechanism from a radical chain growth to a step growth-like mechanism, thus giving a more regulated network architecture and improving final material properties.3 The most prominent CTAs are thiols (thiol-ene-chemistry),4 but Allonas et al.5 also proposed silanes as possible transfer agents for various enes in 2008.
Based on this publication a detailed look at this promising chemistry was taken. Consequently, we were already able to show the efficiency of silanes in silane-acrylate photopolymer networks.6,7 Herein, we now also introduce silane-vinyl ester chemistry for radical photopolymerisation. The chain transfer activity is confirmed via NMR spectroscopy and GPC measurements. Furthermore, silane-vinyl ester-based photopolymers were produced and their curing and thermo(mechanical) performance compared to a reference thiol-ene system.

Photopolymers, protective and decorative coatings, 3D-printing, vinyl esters,