Preparation, Characterization and Antibacterial Activity of Quaternized Carboxymethyl Chitosan/Organic Rectorite Nanocomposites

Quaternized carboxymethyl chitosan/organic rectorite (QCMC/OREC) nanocomposites with different ratios were rapidly prepared under microwave irradiation for 70min. The whole preparation proceeded in water without any organic solvent. The structures of QCMC/OREC nanocomposites were characterized by XRD, TEM and FT-IR. The results showed that the QCMC chains were inserted into silicate layers to form the intercalated or exfoliated nanocomposites, and there were hydrogen bonds and electrostatic interaction between QCMC and OREC. The interlayer distance of the layered silicates in QCMC/OREC nanocomposites was not proportional to the amount of QCMC; it increased firstly to reach a peak value before it decreased with the increase of the QCMC amount; when the weight ratio of QCMC to OREC was 4:1, the exfoliated QCMC/OREC nanocomposite was obtained. The thermogravimetric analysis revealed that the thermal stability of QCMC/OREC nanocomposites was higher as compared to QCMC. In vitro antimicrobial assay showed that QCMC/OREC nanocomposites had stronger antimicrobial activity than original QCMC, particularly against Gram-positive bacteria. With the increase of the amount and the interlayer distance of the layered silicate, the nanocomposites showed stronger antibacterial effect. Therefore, this work provides important basis for developing new antibacterial materials.