Synthesis of silver nanoparticles embedded novel hyperbranched urethane alkyd-based nanocomposite for high solid antimicrobial coating application

In this study, we describe a simple method for the synthesis of a novel nanocomposite comprising hyperbranched urethane alkyd and silver nanoparticle (embedded in the resin) for a high-solid antimicrobial coating application. During the process, silver benzoate was dispersed in the hyperbranched alkyd (HBA) resin containing free hydroxyl groups and the resin is cured with an isocyanate trimer (Desmodur N3390) to make a silver nanoparticle-based nanocomposite coating. Silver benzoate is reduced by the free radicals, generated from naturally occurring oxidative curing of the fatty acid present in the alkyd resin. Unlike a conventional method, which involves the use of a toxic reducing agent or solvent, the present process does not require any toxic reducing agent for the generation of silver nanoparticles. The formation of silver nanoparticle was confirmed by spectroscopic and electron microscopic analysis. The HBA resin used in this work requires a much lesser amount of solvent for making a coating formulation and offers superior mechanical properties compared to the conventional alkyds. The surfaces coated with the nanocomposite coating showed excellent antimicrobial activity against Serratia marcescens bacteria.