Properties and Preparation of Chitosan/Silanol Quaternary Ammonium Modified Silica Hybrids Using Sol-Gel Process

Chitosan/modified silica nanocomposites, with a sol-gel process being used to prepare a silanol quaternary ammonium modified silica possessing antimicrobial activity, were investigated, as well as the thermal properties, morphology, optical, mechanical, antimicrobial, and adsorption properties of this type of nanocomposite. Grafting of the modifier onto nanosilica was confirmed through the Fourier transform infrared (FTIR) spectra. X-ray diffraction patterns indicated that the chitosan structure was not disrupted from the incorporation of the modified silica. Fracture surfaces with no clear micro-phase separation were observed by scanning electron microscopy (SEM), which indicated the good interaction of chitosan and the modified silica. The organic modifier tended to cause the aggregation of the modified silica at higher content on a submicron scale based on transmission electron microscopy (TEM) analysis, which might be due to a decrease of the stability factor originating from the negative charges on silica. With the introduction of modified silica, the optical transmittance decreased at higher organic modifier content in agreement with TEM analysis. The elongation at break remained largely unchanged, but tensile strength and Young's moduli deteriorated in modified silica filled systems in comparison with pure silica filled systems. The introduction of the organic modified silica gave a higher antibacterial activity. All nanocomposites were capable of chelating Cu (II) as well as Fe (III) at a different degree. Thus, the prepared chitosan/modified silica nanocomposites exhibited both antimicrobial and chelating properties.