The controlled in-situ growth of silver-halloysite nanostructure via interaction bonds to reinforce a novel polybenzoxazine composite resin and improve its antifouling and anticorrosion properties

Halloysite nanotube (H) is a renewable aluminosilicate material that can act as a nano-container to carry metal nanoparticles. In the present work, the external sheet of the halloysite nanotube was grafted with 3-aminopropyltriethoxysilane (APTES) and 2-furoyl chloride, which effectively enabled the interaction between Ag ions and the nitrogen/oxygen atoms of the grafted chemical units via their active lone pair electrons and empty orbits. Ag nanoparticles were precisely controlled in-situ to grow on the H external sheet and inner lumen. The strong Ag -N/O interaction allowed the Ag cations dissolved from the Ag nanoparticles to be partially stored on the nanotubes for slow release. The interaction was experimentally verified by antibacterial measurements and computationally illustrated by density functional theory (DFT). The Ag-functionalized halloysite nanotubes were in-situ introduced into a novel coating and bonded in the composite polybenzoxazine framework. Such a high density structure coating exhibited outstanding antifouling performance, such as bacterial killing and anti-attachment. It was also extraordinarily corrosion-resistant in immersion and salt-spray environment for 126 days, much better than most of the coating systems reported so far. The study could extend practical applications of the eco-friendly and multifunctional composite coating in the industry.