Chitosan derivatives with dual-antibacterial functional groups for antimicrobial finishing of cotton fabrics

The three water-soluble chitosan derivatives bearing double functional groups were synthesized with 2,3-epoxypropyltrimethylammonium chloride and benzaldehyde as modifiers through formation of Schiff base, reduction, N-methylation and O-quaternization. The synthesized chitosan derivatives were applied to cotton fabrics together with citric acid (CA) as the crosslinking agent to evaluate their use as durable antimicrobial textile finishing agents. The optimal finishing conditions were investigated and antibacterial activities of finished fabrics were tested with “Shake-Flask Test”. The fabrics finished showed strong antimicrobial activities and fairly good durability. The antibacterial efficiency of S. aureus and E. coli was more than 99% and 96% respectively, when crosslinked with CA (14%, o.w.f) through a two-bath process. The order of antimicrobial activities of the chitosan derivatives was O-quaternized-N,N-biethyl-N-benzyl ammonium chitosans chloride (O-QCTS-DEBn) ≥ O-quaternized-N-chitosan Schiff bases (O-QCTSS) > O-quaternized-N-benzyl-chitosans (O-QCTS-Bn). The antibacterial activity of using O-QCTSS finishing fabric was still more than 75% after 20 consecutive home launderings.