posted on 2021-04-29, 12:33authored byJuho Antti Sirviö, Anu M. Kantola, Sanna Komulainen, Svitlana Filonenko
In this study, the
chemical modification of chitosan using itaconic
acid as a natural-based unsaturated dicarboxylic acid was investigated.
In an aqueous environment, the amine group of chitosan reacts with
itaconic acid to produce a chitosan derivative with pyrrolidone-4-carboxylic
acid group. On the basis of the elemental analysis, 15% of the amine
groups of chitosan reacted, thus creating modified chitosan with amine
and carboxylic acid functionalities. Due to the presence of amine
and carboxylic acid groups, the surface charge properties of the chitosan
were notably altered after itaconic acid modification. In an aqueous
solution, the modified chitosan exhibited zwitterionic properties,
being cationic at low pH and turning anionic when the pH was increased
over 6.5, whereas the original chitosan remained cationic until pH
9. Furthermore, it was demostrated that the modified chitosan was
suitable for the preparation of a self-standing film with similarly
high transparency but notably higher mechanical strength and oxygen
barrier properties compared to a film made from the original chitosan.
In addition, the thermal stability of the modified chitosan film was
higher than that of the original chitosan film, and the modified chitosan
exhibited flame-retardant properties.