Acrylates and methacrylates are current state-of-the-art monomers for UV curable formulations. A large variety of mono-, di-, and multifunctional (meth)acrylates of low and high molecular weight is present on the market today. They are generally used as protective and decorative coatings and have found applications as paints, surface coatings, printing inks, resists, etc. Some selected methacrylates are also used as biocompatible materials, such as bone cements or dental filling materials. These monomers possess many attractive properties, such as good storage stability, fast curing rates, tunable mechanical properties, and allow solvent free processing. However, higher price of these monomers in comparison with other common monomers (e.g. styrene) has to be accepted due to their preparation from (meth)acrylic acid. Furthermore, some methacrylates and especially acrylates and acrylamides exhibit some specific unattractive properties regarding their toxicology profile. Skin irritancy or toxicity of some monomers will be a serious reason to limit their use due to health and environmental legislation. These drawbacks can be mainly addressed to the reactivity of the acrylate double bond towards Michael Addition reactions with amino- or thiol- groups of proteins.

There are not many alternatives if one wants to sustain the excellent performance profile of (meth)acrylates and the polymers thereof along with lower irritancy or cytotoxicity of the monomers. Vinyl esters might be a good substitute. However, currently there are only few monofunctional, one difunctional, and no multifunctional vinyl esters commercially available. It has been shown recently that this class of monomers has a surprisingly high photoreactivity and low cytotoxicity and thus could be a suitable alternative to (meth)acrylates [1]. However, hydrolytic sensitivity of the less sterically demanding ester group is a serious disadvantage. Alternative monomers are based on Vinylcarbonates [2]. Current synthetic routes to vinyl carbonates are expensive and only suitable for laboratory scale preparation. Therefore these monomers have not been studied in detail by the scientific community and have hardly been used in industrial applications. Nevertheless, a recent patent from BASF describes a high-yield synthesis from cheap reagents applicable on industrial scale which may afford even cheaper monomers than (meth)acrylates [3]. By using a thiol-ene polymerization even higher reactivity than acrylates has been demonstrated recently.

[1] 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), 6941 - 6954.

[2] 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", J. Polym. Sci., Part A: Polym. Chem., 2010, 49, 650-661.

[3] W. Staffel, R. Kessinger, J. Henkelmann, "Method for the production of O-vinylcarbamates and vinylcarbonates" WO2008/084086 (2008).

[4] A. Mautner, X. Qin, H. Wutzel, S. C. Ligon,B. Kapeller, D. Moser, G. Russmueller, J. Stampfl, R. Liska „Thiol-Ene Photopolymerization for Efficient Curing of Vinyl Esters“ J Polym Sci, A, 2013, 51, 203-212.