Poly(benzoxazine-f-chitosan) films: The role of aldehyde neighboring groups on chemical interaction of benzoxazine precursors with chitosan.

This study reports the preparation and characterizations of chitosan-azomethine derivatives containing oxazine ring as new crosslinked polymers. The novel chitosan derivatives have been prepared by functionalization with reactive benzoxazine precursors. Two types of aldehyde-terminated benzoxazine precursors have been synthesized using two different polyetheramines (Jeffamines), 4-hydroxybenzaldehyde, and paraformaldehyde. The benzoxazine precursors are covalently attached to chitosan via Schiff's base formation. Benzoxazine structure is confirmed by proton nuclear magnetic resonance spectroscopy (1H-NMR) and Fourier transform infrared spectroscopy (FT-IR), whereas the imine-linkage formation is confirmed by FT-IR. The benzoxazine-f-chitosan films are crosslinked by cationic ring-opening polymerization of benzoxazine. Differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA) are used to study the thermal behavior of the obtained films. Wettability behavior of the resulting films was studied by contact angle measurements and compared with wettability of the neat chitosan film.