Greimel, Katrin; Perz, Veronika; Koren, KlausIST Austria; Feola, Roland; Temel, Armin; Sohar, Christian; Herrero Acero, Enrique; Klimant, Ingo; Guebitz, Georg
Alkyd resins are polyesters containing unsaturated fatty acids that are used as binding agents in paints and coatings. Chemical drying of these polyesters is based on heavy metal catalyzed cross-linking of the unsaturated fatty acid moieties. Among the heavy-metal catalysts, cobalt complexes are the most effective, yet they have been proven to be carcinogenic. Therefore, strategies to replace the cobalt-based catalyst by environmentally friendlier and less toxic alternatives are under development. Here, we demonstrate for the first time that a laccase-mediator system can effectively replace the heavy-metal catalyst and cross-link alkyd resins. Interestingly, the biocatalytic reaction does not only work in aqueous media, but also in a solid film, where enzyme diffusion is limited. Within the catalytic cycle, the mediator oxidizes the alkyd resin and is regenerated by the laccase, which is uniformly distributed within the drying film as evidenced by confocal laser scanning microscopy. During gradual build-up of molecular weight, there is a concomitant decrease of the oxygen content in the film. A new optical sensor to follow oxygen consumption during the cross-linking reaction was developed and validated with state of the art techniques. A remarkable feature is the low sample amount required, which allows faster screening of new catalysts.
This study was performed within the Austrian Centre of Indus- trial Biotechnology ACIB and the COST Action 868. This work has been supported by the Federal Ministry of Economy, Family and Youth (BMWFJ), the Federal Ministry of Tra ffi c, Innovation and Technology (bmvit), the Styrian Business Promotion Agency SFG, the Standortagentur Tirol and ZIT – Technology Agency of the City of Vienna through the COMET-Funding Program managed by the Austrian Research Promotion Agency FFG. Dr Massimiliano Cardinale (Institute of Environmental Biotechnology, TU Graz) is gratefully acknowl- edged for technical support with the CLSM measurements.
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Greimel K, Perz V, Koren K, et al. Banning toxic heavy-metal catalysts from paints: Enzymatic cross-linking of alkyd resins. Green Chemistry. 2013;15(2):381-388. doi:10.1039/c2gc36666e
Greimel, K., Perz, V., Koren, K., Feola, R., Temel, A., Sohar, C., … Guebitz, G. (2013). Banning toxic heavy-metal catalysts from paints: Enzymatic cross-linking of alkyd resins. Green Chemistry. Royal Society of Chemistry. https://doi.org/10.1039/c2gc36666e
Greimel, Katrin, Veronika Perz, Klaus Koren, Roland Feola, Armin Temel, Christian Sohar, Enrique Herrero Acero, Ingo Klimant, and Georg Guebitz. “Banning Toxic Heavy-Metal Catalysts from Paints: Enzymatic Cross-Linking of Alkyd Resins.” Green Chemistry. Royal Society of Chemistry, 2013. https://doi.org/10.1039/c2gc36666e.
K. Greimel et al., “Banning toxic heavy-metal catalysts from paints: Enzymatic cross-linking of alkyd resins,” Green Chemistry, vol. 15, no. 2. Royal Society of Chemistry, pp. 381–388, 2013.
Greimel K, Perz V, Koren K, Feola R, Temel A, Sohar C, Herrero Acero E, Klimant I, Guebitz G. 2013. Banning toxic heavy-metal catalysts from paints: Enzymatic cross-linking of alkyd resins. Green Chemistry. 15(2), 381–388.
Greimel, Katrin, et al. “Banning Toxic Heavy-Metal Catalysts from Paints: Enzymatic Cross-Linking of Alkyd Resins.” Green Chemistry, vol. 15, no. 2, Royal Society of Chemistry, 2013, pp. 381–88, doi:10.1039/c2gc36666e.