This project has received funding from the European Union's Horizon Europe Framework Programme under grant agreement number 101058554. This work was co-funded by the Swiss State Secretariat for Education, Research and Innovation (SERI) and the UK Research and Innovation (UKRI) under the UK government's Horizon Europe funding guarantee grant number 10042534 & grant number 10055606. 2nd NOVA General Assembly| Smolenice Castle| 2023 Stability/Lifespan Durability Chemical/ Abrasion resistance Surface material compatibility Ease of application Water- or solvent-based Appearance Possible impact on the function of the coated object Leaching Toxicological/environmental concerns More information about the Author? Permanent coatings: model paint formulations for photocatalysts Fraunhofer IFAM, Bremen (D) DOI: 10.5281/zenodo.8332165 Claus Schreiner, Dorothea Stübing, Malinn Kastens and Thalea Czarnik Strengths • identification of an efficient photocatalyst in combination with a durable matrix would open up ways for very long lasting effects • combinations with the upconverter pigments could lead to synergistic booster effects • pure anatase is a pigment commonly used in cosmetics and pharmaceuticals, so no toxicity is expected concerning the undoped material Weaknesses • as the particles are based on TiO2, all functionalized coatings are at least hazy and can be white to greyish/beige (in case of doped TiO2) • the effects observed are lasting, but only moderately active • quite high concentrations of particles can be necessary which influences the general coating performance • the coating matrices must be robust, otherwise they are decomposed as well Opportunities • the applicability is very universal, all common coating matrices can be used • TiO2 is a friendly pigment referring to viscosity properties; in case of white/grey coatings, the functionalization is “invisible” • various photocatalytic materials are commercially available and not excessively high priced • the incorporation in the coating uses standard dispersion techniques (material behaves like rutile TiO2) • regulatory aspects (although it seems that TiO2 has already gone through this “process”) • too high amounts of photocatalyst added can reduce key features of a given coating (e.g. substrate adhesion) • starting from clearcoats, the milkiness of the functional coatings might be undesired by the market/customer Threats & Risks Functional Requirements Non-functional Requirements • Light (visible to UV-A) as well as moisture is necessary for the photocatalytic process; moisture must be available at least at a molecular level (no macroscopic water!) • the coating matrices must be robust, otherwise they are decomposed as well over time • the coating matrix must be suitable for the application purpose 1. Claus Schreiner, Volker Zöllmer: Fraunhofer-funded „Covid Dekont“ project, www.compamed.de („Im Kampf gegen Viren und Bakterien – Desinfektion mit Licht“), 04/2022. Features • photocatalysts are usually based on the titanium dioxide modification anatase; except for the photocatalytic activity, the properties are similar to rutile = “common” TiO2 • in the presence of light (UV to visible) and moisture, radicals are formed which decompose organic matter (like bacteria) • as the polymer matrix is also organic, robust coatings are mandatory for lasting effects Goals (Product Vision) • versatile coatings with durable antimicrobial properties by: • screening of a variety of photocatalysts to figure out their strengths and weaknesses • examination of different coating matrices with respect to the interactions with the photocatalysts (e.g. regarding resistance or inhibition) • studies on combinatorial approaches with Evonik’s upconverter pigments Durable coatings with unlimited antimicrobial effect depends on the coating matrix; the particles themselves are stable (inorganic pigments!) again, dependent on the coating matrix; surface abrasion leads to uncovered pigments and thus to incr