Polyamide powder coatings with superior flowability for antibacterial application via microwave-driven spheroidization and in-situ self-assembly of AgNPs

Since environmental pollution and bacterial infections seriously threaten human health, considerable attention is devoted to designing antibacterial powder coatings. Silver nanoparticles (AgNPs) in the antibacterial coatings are recognized widely yet have not been well developed for powder coatings due to the size, carriers, dispersity and Ag⁺ release of AgNPs. Herein, polyamide-based (PA) powder coating is prepared by microwave-driven spheroidization of PA particles and in-situ self-assembly of AgNPs based on polydopamine as active sites. PA particles with a sphericity of 0.93 show near perfect round morphology. It is conducive to decreasing the particle interactions, such as van der Waals and electrostatic forces, compared to irregular ones, thereby exhibiting superior flowability. Owing to AgNPs with a size of 75 ± 3 nm in coatings showed adaptable Ag⁺ release rate, superior dispersity and interface compatibility. The coatings thus present durable antibacterial properties and wear resistance. Results demonstrated that the coatings containing 1.0 wt% AgNPs exhibited 99.99 % reduction for E. coli and S. aureus. Moreover, it is against presenting the same activity as the original coatings after 500 rub cycles or immersion for 7 days. Finally, as-prepared powder coating was used in door handles and wheelchair hand rims, proving its potential usefulness in public health devices.