Zinc Borate Nanoparticle-Loaded Carboxymethyl Chitosan Aerogels for Flame Retardancy and Acoustic Absorption

In this paper, zinc borate nanoparticles were synthesized by in situ synthesis using zinc nitrate and sodium tetraborate as raw materials, and zinc borate nanoparticles were loaded onto carboxymethyl chitosan aerogel prepared by directional freezing in combination with a freeze-drying technique, and zinc borate (ZB)/carboxymethyl chitosan composite aerogels (ZBAs) with excellent multifunctionality have been successfully prepared. The thermal behavior of carboxymethyl chitosan aerogel (CCSA) and ZBAs was analyzed using TG and DTG, and the flame retardancy of the composite aerogel was explored by simple vertical combustion experiments, where the introduction of ZB significantly improved the flame retardancy of CCSA. Meanwhile, the presence of ZB did not affect the porous structure of the aerogels, and the average acoustic absorption coefficient of the ZBA was the lowest at 0.58, and the maximum value of the thermal conductivity was 0.069 W·m–1·k–1, which indicated that the aerogels were loaded with zinc borate nanoparticles for effective thermal insulation and acoustic absorption. Moreover, the composite aerogel maintained excellent antimicrobial properties after the addition of zinc borate nanoparticles. The results of this study provide ideas for the comprehensive application of carboxymethyl chitosan aerogels in different fields.