Creation of Biocidal Coatings using the Stabilization of Silver Nanoparticles in Aqueous Acrylic Dispersions

This article proposes a method for silver nanoparticle (AgNP) stabilization in polymer coatings obtained from aqueous acrylic dispersions. The main objective of the study was to improve the biocidal properties of coatings using AgNPs due to the preservation of their nanoscale state. Two types of AgNP solutions with fundamentally different stabilization mechanisms were synthesized and compared. Two mechanisms were determined: an aqueous electrostatic mechanism with sodium docusate stabilizer (AOT) and a steric, propylene glycol with polyvinylpyrrolidone (PVP) stabilizer. The results showed that both solutions were unstable and prone to precipitation as early as the first day after synthesis. However, the saturation of the propylene glycol AgNP solution with ammonium hydroxide to pH < 9 allowed the strengthening of the electrostatic factor of aggregative stability, providing optimal conditions for mixing with acrylic dispersions stabilized by anionic surfactants. The obtained AgNPs in the acrylic dispersions stabilized over time, and when they became film-forming, stable AgNPs (similar to 20-30 nm) occurred on the surface. As a result, the developed coatings using AgNPs synthesized in propylene glycol in the presence of non-ionic PVP and modified with ammonium hydroxide, demonstrated a high inactivation of bacteria colony-forming units (CFU) (> 60%) within 60 min of contact compared to aqueous AgNP solutions using anionic surfactants as stabilizers, where the decrease in CFU was around 25%.