Silver nanoparticles as antifungal agents in acrylic latexes: influence of initiator on nanoparticle encapsulation efficiency and leaching

Abstract

Nanoparticles present undeniable benefits in the formulation of cosmetics, construction materials, and coatings due to their optical, mechanical, and antimicrobial properties. However, a major limitation of application of nanoparticles in composite materials is nanoparticle leaching, which could have potential negative impacts on ecosystems and living organisms. This study investigates the influence of using an organic vs. water-soluble initiators (azobisisobutyronitrile and potassium persulfate, respectively) on the encapsulation and subsequent leaching of silver nanoparticles (AgNPs) from acrylic latexes prepared by miniemulsion polymerization. For comparison purposes, a reference latex was also prepared by the simple post-addition of hydrophilic AgNPs. AgNP encapsulation efficiencies were determined from density gradient column separations and latex particle size analysis was performed by dynamic light scattering. The spatial distribution of AgNPs in dry films was determined by scanning electron microscopy coupled with energy-dispersive spectroscopy and by mapping Ag signal using laser ablation inductively coupled plasma-time of flight-mass spectrometry. AgNP leaching was determined by measuring the acrylic film silver content before and after exposure to conditions designed to simulate rainfall (water leaching). The encapsulation of AgNPs using miniemulsion polymerization decreases particle leaching with respect to films prepared from the post-addition technique. The use of the organic-soluble initiator results in a better encapsulation of AgNPs and better NP retention during water leaching. Therefore, nanoparticle encapsulation using miniemulsion polymerization and an organic-soluble initiator minimizes the release of AgNPs from dry films and thus could mitigate the negative environmental impact of AgNPs.

Graphical Abstract