Characterization of carboxymethyl cellulose-based active films incorporating non-modified and Ag or Cu-modified Cloisite 30B and montmorillonite nanoclays

Physico-mechanical and antibacterial properties of carboxymethyl cellulose (CMC)-based films incorporating Cloisite 30B (C30B) and montmorillonite (MMT) clay nanoparticles (NPs) modified with Ag and Cu ions were investigated. X-Ray diffraction patterns for modified clays with Ag and Cu ions showed that they were effectively located in the interlayer space of C30B and MMT clay NPs and increased their interlayer spacing. Scanning electron microscopy showed a smooth and homogeneous structure for a pure CMC film. Films containing MMT had coarser and more heterogeneous surface compared to C30B film, suggesting a better dispersion of modified C30B in the matrix of CMC. Mechanical analysis showed that films containing Ag- or Cu-modified C30B NPs exhibited higher tensile strength than that of MMT films. The ultraviolet spectroscopy showed that nanocomposite films containing Ag modified C30B had the highest UV absorption compared to other samples. Water vapor permeability of CMC films loaded by Ag- or Cu-modified C30B and MMT NPs significantly decreased compared to those of non-modified types and control. Microbial tests revealed that Ag-modified clay NPs had significantly higher antibacterial activity than Cu-modified types against E. coli and S. aureus bacteria. Films loaded with non-modified C30B NPs had the second most antibacterial effect followed by non-modified MMT NPs and control films.