Rice straw nanofibrillated cellulose films with antimicrobial properties via supramolecular route

Novel antimicrobial nanofibrillated cellulose (NFC) with new optical and good tensile strength properties was prepared through supramolecular modification of TEMPO-oxidized NFC by Cu-, Zn-, and Fe-terpyridine metal complexes (M-Tpy). The prepared terpyridine-modified NFC (NFC-M-Tpy) derivatives were characterized using transmission electron microscopy (TEM), Fourier transform infrared (FTIR), and elemental analysis. Films casted from aqueous suspensions of NFC-M-Tpy plasticized by glycerol were made and characterized using X-ray diffraction (XRD), tensile strength, porosity, water vapor permeability, and antimicrobial properties testing. Attaching the different M-Tpy moieties to NFC resulted in increasing tensile strength and Young's modulus, decreasing porosity and water vapor permeability (WVP), and imparted NFC antimicrobial properties against Gram-positive bacteria (Staphylococcus aureus), Gram-negative bacteria (Escherichia coli), as well as yeast (Saccharomyces cervisiae). NFC-Cu-Tpy film showed higher antimicrobial properties than NFC-Zn-Tpy and NFC-Fe-Tpy films while the other properties tested showed independence on the type of metal center in the terpyridine complex. The NFC-Cu-Tpy was used for coating bagasse paper sheets and tensile strength, burst strength, water vapor permeability, porosity, and water sorption of coated paper sheets were tested. NFC-Cu-Tpy coating improved tensile strength properties and reduced porosity, WVP, and water absorption of coated paper sheets more than in case of using NFC. The prepared nanocellulosic materials can find potential applications in active packaging and healthcare paper products. (C) 2016 Elsevier B.V. All rights reserved.