In this study, antibacterial polyelectrolyte/silver nanoparticle (Ag NP) composite powder was mixed with epoxy resins as fillers to impart antibacterial activity. Either an anhydride-type or a polyamideamine-type curing agent was applied to a bisphenol A-type base compound to prepare the epoxy resins. Antibacterial assays of these resins against Escherichia coli were performed using the shake tube technique; suppression of antibacterial activity was found for the anhydride-type resin, although the polyamideamine-type resin did exhibit antibacterial activity. The anhydride-type resin is considered to have suppressed antibacterial activity because carboxylate ions derived from unreacted anhydride in aqueous medium can induce chemical adsorption of silver ions and/or charge repulsion of E. coli.
Keywords: Eschericha coli; Nanocomposite; Thermosetting resin.