Functional group modification on the surface of chitosan film via reaction of amino group

Abstract

Chitosan, partially deacetylated form of chitin, is a natural polymer. Structure of chitosan contains a large number of hydroxy and amino groups, which can be modified by various chemical reactions. This research focused on the reactions between the amino groups of chitosan and derivatives of carboxylic acids, e.g., phthalic anhydride, succinic anhydride, m-iodobenzoyl chloride, stearyl chloride, and heptafluorobutyryl chloride to form an amide bond. The chemical modification was performed by immersing chitosan films in a selected reagent. Surface analysis by X-ray photoelectron spectroscopy (XPS) revealed traces of halogen atoms, indicating a success in attaching the halogenated compounds to chitosan. Results from contact angle measurement suggested that surface hydrophilicity of chitosan films increased after the reaction with phthalic and succinic anhydride. On the other hand, the hydrophilicity is decreased after the reaction with stearic acid. Moreover, derivatization of the amino groups on the film surface was confirmed by ATR-FTIR. Last, these modification methods somewhat affected the adsorptivity of albumin and lysozyme on the film surface.