Synthesis and characterization of N-alkylchitosan as well as its potency as a paper coating material

Abstract

N-Alkylchitosan is an amphiphilic chitosan’s derivative. Its alkyl side chain is hydrophobic and will reduce the water-absorption capacity of the hydrophilic chitosan. Therefore, it can be applied as waterproof paper coating in food packaging paper. In this study, N-alkylchitosan is synthesized from commercial chitosan having 86% deacetylation degree. Two synthetic methods were compared, in heterogenous system using suspended chitosan in methanol and homogenous system where chitosan was dissolved in 1% acetic acid at the first stage. The infrared spectra showed that synthesis conducted in homogenous system successfully synthesized N-octylchitosan. The degree of substitution (DS) value of the N-octylchitosan was 0.16, based on proton nuclear magnetic resonance analysis. Derivatives with longer alkyl side chain (N-decyl and N-dodecylchitosan) exhibited much lower DS, that is 0.02, which is predicted as the effect of increased steric hindrance. Therefore, based on this study, N-octylchitosan is the most potential as a waterproof paper coating because it has the highest value of DS.