Preparation of amphiphilic nano-sized NaA/glass films and powders using layer-by-layer in-situ sol-gel method

Nano-sized NaA/glass films were prepared by a layer-by-layer in-situ sol-gel method combined with the steam-assisted conversion technique. Consequently, nano-sized zeolite NaA powders were obtained by scraping the films and treating the resultant powders with a 0.6% acetic acid solution. The films and the powders were characterized by XRD, FT-IR, SEM, TEM, and AFM, and their hydrophilicity and antimicrobial activity after Ag⁺-exchange were examined. The preparation conditions such as the reaction time and the amount of water prefilled in the autoclave were examined. The NaA crystals on the films are about 50-100 nm in size and they are aggregated together. Their particle sizes can be further reduced to 40-80 nm and they can be changed from aggregated to highly dispersed particles after treated in the acid solution. The amount of water during the synthesis is quite important for successful synthesis of well-crystallized nano-sized zeolite NaA on the glass. And dispersed 40-50 nm zeolite NaA particles can be obtained when suitable amount of water is used. The nano-sized NaA/glass film exhibits superhydrophilicity and oleophilicity. After ion-exchange with Ag⁺, the NaA/glass film shows high antimicrobial activity, better than the nano-sized NaA powders and other NaA films or coatings reported in literature.