Preparation of β-chitin nanofiber aerogels by lyophilization.

In this study, chitin nanofiber dispersions prepared in neutral and acidic pH conditions were lyophilized to produce aerogels. The effects of the freezing speed of the nanofiber dispersions and the dispersibility of the chitin nanofiber were studied. The characteristics of the aerogels were studied using scanning electron microscopy, relative surface area measurements, and compression tests. The repulsion forces of the chitin nanofiber in acidic conditions were effective in the formation of a more uniform microstructure during water solidification, resulting in aerogels with a high mechanical strength. The aerogel made from the chitin nanofiber dispersion prepared in neutral conditions was influenced by ice crystal growth during freezing, resulting in a nonuniform structure. In contrast, the surface area of the aerogel in neutral conditions interestingly remained unchanged compared to that of the original powder, which was due to the morphological transformation.