Taking into account the adverse effects of acrylates, new monomers with different polymerizable groups such as methacrylated gelatin [1] and other monomers based on vinyl esters, [2] vinyl carbonates and vinyl carbamates [3] have been developed. These new monomers were found to be significantly less cytotoxic than acrylates. Moreover, polymers derived from these classes of monomers give water-soluble and biocompatible poly(vinyl alcohol) as degradation product. Sometimes slow reactivities can be circumvented by using the thiol-ene chemistry [4,5]. One of the main chalenges is the still brittle behaviour of these materials due to the uncontrolled chain growth polymerization. Oligomeric building blocks in combination with the Hot Lithography technique are a suitable pathway to improve the toughness [6]. To speed up the degradation process acetal moieties were recently introduced [7].

[1] M. Schuster, C. Turecek, G. Weigel, R. Saf, J. Stampfl, F. Varga, R. Liska: "Gelatin-Based Photopolymers for Bone Replacement Materials"; Journal of Polymer Science Part A: Polymer Chemistry, 47 (2009), S. 7078 - 7089.

[2] C. Heller, M. Schwentenwein, G. Russmüller, F. Varga, J. Stampfl, R. Liska: "Vinyl Esters: Low Cytotoxicity Monomers for the Fabrication of Biocompatible 3D Scaffolds by Lithography Based Additive Manufacturing"; Journal of Polymer Science Part A: Polymer Chemistry, 47 (2009), S. 6941 - 6954.

[3] C. Heller, M. Schwentenwein, G. Russmüller, T. Koch, D. Moser, C. Schopper, F. Varga, J. Stampfl, R. Liska: "Vinylcarbonates and Vinylcarbamates: Biocompatible Monomers for Radical Photopolymerization"; Journal of Polymer Science Part A: Polymer Chemistry, 49 (2011), 3; S. 650 - 661.

[4] A. Mautner, X.H. Qin, H. Wutzel, B. Kapeller, D. Moser, G. Russmüller, J. Stampfl, R. Liska: "Thiol-Ene Photopolymerization for Efficient Curing of Vinyl Esters"; Journal of Polymer Science Part A: Polymer Chemistry, 51 (2012), 1; S. 203 - 212.

[5] A. Mautner, X.H. Qin, B. Kapeller, G. Russmüller, T. Koch, J. Stampfl, R. Liska: "Efficient Curing of Vinyl Carbonates by Thiol-Ene Polymerization"; Macromolecular Rapid Communications, 33 (2012), 23; S. 2046 - 2052.

[6] S. Orman, C. Hofstetter, A. Aksu, F. Reinauer, R. Liska, S. Baudis: "Toughness enhancers for bone scaffold materials based on biocompatible photopolymers"; Journal of Polymer Science Part A: Polymer Chemistry, 56 (2018), 24; S. 110 - 119.

[7] B. Dellago, A. Ricke, T. Geyer, R. Liska, S. Baudis: "Photopolymerizable precursors for degradable biomaterials based on acetal moieties"; European Polymer Journal, 154 (2021), 110536; S. 1 - 12.