Hydrophobically modified chitosan: A bio-based material for antimicrobial active film

The objective of the present research was to improve the hydrophobicity of chitosan, while retaining its antibacterial activity, through the grafting of dodecenyl succinyl chains onto phthaloyl chitosan, mainly at the C-6 position. Dodecenyl succinylated phthaloyl chitosan (DS-g-PHCTS) was synthesized via phthaloylation–dodecenyl succinylation–hydrazinolysis. The obtained derivatives were characterized by FTIR, 1H NMR and XRD. Hydrazinolysis time was found to be a key factor in controlling the substitution of dodecenyl succinyl chains and phthalimido groups of the final product. DS-g-PHCTS – with a grafting degree of dodecenyl succinyl chains and a substitution degree of phthalimido groups of 0.73 and 0.39, respectively – exhibited an anhydrous crystal structure and the same solubility behavior as native chitosan. The introduction of hydrophobic alkyl chains provided DS-g-PHCTS with enhanced antibacterial activity against Gram-positive bacteria. In addition, DS-g-PHCTS film showed more effective bacterial growth inhibition and better water vapor barrier property under neutral pH condition than chitosan film. The results suggested that DS-g-PHCTS film could be potentially used as antibacterial active film.