Chemical modification of chitosan with cationic hyperbranched dendritic polyamidoamine and its antimicrobial activity on cotton fabric

The cationic hyperbranched dendritic polyamidoamine (PAMAM) containing terminal methyl ester end groups was synthesized and then employed for modifying flake chitosan. The synthesis was achieved using repetitive reactions between Michael addition and amidation to obtain the methyl ester group terminated hyperbranched PAMAM, and then the methyl ester terminated hyperbranched dendritic PAMAM (PAMAM-ester) was methylated with dimethyl sulphate. The subsequent modification of chitosan with the cationic hyperbranched PAMAM-ester was carried out at room temperature for 5 days. As a result, cationic hyperbranched PAMAM modified chitosan was achieved. Characterizations by elemental analysis, FT-IR, NMR, TGA and XRD were employed to investigate the structural changes of chitosan to confirm its configuration. The cationic hyperbranched PAMAM-chitosan was applied onto cotton fabric at 1 wt.% add-on using a padding method and was found to have a good antimicrobial performance against Staphylococcus aureus compared to that obtained with unmodified chitosan.