Cationic surface modification of nanocrystalline cellulose as reinforcements for preparation of the chitosan-based nanocomposite films

Nanocrystalline cellulose (NCC) is a promising nanofiller for reinforcing chitosan (CTS) film. The flocculation of the NCC suspension in acidic CTS solution is the key problem that makes many properties such as the tensile strength bad. A derivative of nanocellulose, namely cationic dialdehyde cellulose (CDAC), is synthesized in the current study to avoid the flocculation. A CDAC suspension is prepared in a successive oxidation-reductive amination process of NCC. The oxidation of NCC led to smaller rod-like nanocrystals with a reduced crystallinity. The suspension with 1.0% CDAC is well mixed with 1.0% CTS solution. Besides, the tensile strength and anti-swelling properties of CDAC-filled CTS nanocomposite films are improved because of the uniform distribution of CDAC in the CTS matrix plus the intermolecular chemical cross-linking between CDAC and CTS. The tensile strength of CTS-based nanocomposite film with 12% CDAC is about 58.4% higher than that of the pure CTS film.