Synthesis, characterization, and antibacterial activity of N-substituted quaternized chitosan and its cellulose-based composite film

A water and organic soluble N-benzyl-N,N-diethyl quaternized chitosan (NSQC) material was synthesized using chitosan, benzaldehyde, and bromoethane. Amino groups on chitosan reacted with benzaldehyde to form a Schiff base intermediate. Quaternized chitosan was obtained by reacting the Schiff base with bromoethane. The quaternized chitosan was dissolved in an organic solution with dissolved cellulose and cast to prepare quaternized chitosan/cellulose (QCC) film. The molecular structure, morphology, tensile strength, thermal stability, and antibacterial activity effects of NSQC-treated cellulose film were studied in detail. The results showed that the NSQC product exhibited superior solubility in deionized water and dimethylacetamide. The addition of NSQC as a reinforcing agent in QCC film enhanced the interlinking of fibers and slowed down the rate of cellulose pyrolysis, which improved the tensile properties and thermal stability of the cellulose film. The minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) values of NSQC showed that it had good antibacterial activity against Staphylococcus aureus and Escherichia coli. The QCC film also showed contact sterilization ability with regards to two kinds of bacteria, which suggested that QCC film has the potential for applications in food packaging and bacterial barriers.