Synthesis of Reactive Nanoparticles for Coatings with Enhanced Chemical Resistance

Trabalho apresentado em BIT's 5th Annual World Congress of Advanced Materials, 6-8 junho de 2016, Chongqing, ChinaN/

Is it possible to produce superhydrophobic surfaces from water-borne coatings?

Com o apoio RAADRI. Resumo de apresentação oral.Bio-inspired superhydrophobic surfaces have attracted considerable attention due to their excellent water repellent properties and their underlying potential applications. It is very well established in the state of the art that the production of superhydrophobic surfaces requires the use of low surface energy materials carefully tailored with micro/nanostructures to substantially increase the surface roughness. However, as hydrophobic materials are not soluble in water, superhydrophobic coatings are usually formulated with organic solvents, emitting large amounts of undesired volatile organic compounds (VOC) to the atmosphere upon application. The search for a superhydrophobic water-based coating seems contradictory, but is it really impossible to achieve? The goal of the present work is to develop a simple approach to manufacture superhydrophobic top-coats from water-based formulations, for anticorrosion applications. Low water adhesion is highly desirable, in order to achieve the Cassie-Baxter wetting regime and to observe the water roll-off effect

Novel coating containing molybdenum oxide nanoparticles to reduce Staphylococcus aureus contamination on inanimate surfaces

We previously synthetized molybdenum oxide (MoO3) nanoparticles (NP) and showed their antibacterial activity against a representative collection of the most relevant bacterial species responsible for hospital-acquired infections, including Staphylococcus aureus. The aim of the present study was to prepare and characterize a novel coating with these MoO3 NP, confirm its mechanical stability, and investigate its biocidal effect to reduce S. aureus contamination on inanimate surfaces. In addition, the novel MoO3 NP coating was compared to a silver (Ag) NP coating synthetized by the same procedure. The MoO3 and Ag NP coatings were characterized in terms of their chemical structure by FT-IR, surface morphology by scanning electron microscopy, and mechanical properties by tensile and adhesion tests. The antimicrobial activity of the coatings was tested by following the loss of viability of S. aureus after 6h, 24h, 48h, and 72h exposure. MoO3 and Ag coatings exhibited surfaces of comparable morphologies and both presented elastomeric properties (tensile strength of similar to 420 kPa, Youngs modulus of similar to 48 kPa, and maximum elongation of similar to 12%), and excellent (classification of 5B) adhesion to glass, steel and polystyrene surfaces. The two coatings exhibited a good antibacterial activity (R) against S. aureus over time (R-MoO3 = 0.20.81; R-Ag = 0.612.37), although the effect of the Ag NP coating was more pronounced, especially at 72h (R-MoO3 = 0.81 vs R-Ag = 2.37). Noteworthy, contrary to the Ag NP coating, the MoO3 NP coating was colourless and transparent, avoiding undesired unaesthetic effects. The synthetized coating with NP of MoO3, which has low toxicity to humans, capability of biodegradation, and rapid excretion, can be applied onto most standard materials and therefore is a promising tool to reduce S. aureus contamination on usual inanimate surfaces found in healthcare and community environments.info:eu-repo/semantics/publishedVersio