Surface-deacetylated Chitin Nanofibers Research Articles

Surface maleylation and naphthaloylation of chitin nanofibers for property enhancement

Surface N-maleylation and N-naphthaloylation of chitin nanofiber (NF) were achieved by reaction with maleic and naphthalic anhydrides in water, respectively. Maleyl and naphthaloyl groups were sufficiently introduced to an amino group on a surface-deacetylated chitin NF. The characteristic nanofiber morphology was maintained after maleylation and naphthaloylation. These NFs were homogeneously dispersed in several organic solvents. Especially, naphthaloyl chitin NF was dispersed even in aromatic solvents, owing to the high level of solvation interactions with the naphthaloyl group. The NF dispersions in those aromatic solvents exhibited a dispersive-to-precipitate transition response at approximately 29°C. Moreover, the naphthaloyl chitin NF dispersion cut harmful ultraviolet light. The maleyl chitin NF formed a self-standing gel after cross-linking polymerization.

Control of mechanical properties of chitin nanofiber film using glycerol without losing its characteristics

Surface-deacetylated chitin nanofiber films plasticized with glycerol were prepared to control mechanical properties. Nanofiber networks were able to retain excessive glycerol content up to 70% to obtain self-standing film. All films were flexible and highly transparent independent of glycerol content. Glycerol significantly decreased the Young's moduli and tensile strengths, and increased the fracture strain due to its plasticizing effect. At the same time, glycerol did not change the high transparency or the low thermal expansion of the nanofiber film.

Preparation of high-strength transparent chitosan film reinforced with surface-deacetylated chitin nanofibers

Surface-deacetylated chitin nanofiber reinforced chitosan films were prepared. The nano-composite films were highly transparent of approximately 84% at 600nm due to the nanometer-sized fillers and chitosan matrix, which were embedded in the cavities and on the rough surface of the nanofiber networks. Due to the extended crystalline structure, the nanofibers worked effectively as reinforcement filler to improve the Young's modulus and the tensile strength of the chitosan film. After 10% blending of nanofiber, these properties were increased by 65% and 94%, respectively. Moreover, thermal expansion was also significantly decreased from 35.3 to 26.1ppmK−1 after 10% addition of nanofibers. Surface-deacetylated chitin nanofiber and the nano-composite films showed antifungal activity against A. alternata.