pH-Responsive Indicator Poly(vinyl alcohol) Films by Anchoring Neutral Red to TEMPO-oxidized Cellulose Nanofibers
발표자
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초록
내용
In this study, TEMPO-oxidized cellulose nanofibers (TOCNFs) were covalently attached to neutral red (NR) dye to develop intelligent cellulose nanofibers (NR@CNF). By incorporating NR@CNF into poly(vinyl alcohol) (PVA) polymer, the pH-sensitive intelligent films were created. Poly(acrylic acid) (PAA) was utilized as a crosslinking agent to increase PVA's water resistance, and heat treatment accelerated the crosslinking process between them. Binding of NR to TOCNFs was proven by attenuated total reflection infrared (ATR-IR) spectroscopy and X-ray photoelectron spectroscopy (XPS). The color variation of pH-indicator films in pH ranges from 2.0 to 10.0 was assessed using the CIELab technique. Colorimetric results indicated that the developed pH-indicator films had an outstanding color response to pH variations and ammonia at all levels of NR@CNF and PAA. Increasing the quantity of PAA had a detrimental impact on halochromic characteristics while it improved the swelling index, water solubility, tensile strength and modulus of PVA films. Furthermore, the mechanical properties of pH-indicator films enhanced as the NR@CNF concentration increased from 0.1% to 0.5%. Accordingly, the data from this investigation supports the idea that PVA/PAA films with NR@CNF might be useful in packaging systems as pH indicators. However, further research is necessary before they are applied for actual food systems.