Sulfated cellulose nanocrystal isolated from waste cotton fabrics by deep eutectic solvent and its application in polymer nanocomposite films

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The growing utilization of textiles raises concerns about the ecological hazards of textile production methods and discarded textiles. The recycling and reusing of waste cotton materials align with the sustainable development of society. In this study, sulfated cellulose was synthesized by sulfating waste cotton using a deep eutectic solvent (DES). After nanofibrillation with ultrasonication, sulfated cellulose nanocrystal (SCNC) with an average width of 10.83 nm and an average length of 129.40 nm was produced. The thermal properties of the synthesized SCNC were significantly enhanced compared to the pristine cellulose, with a notable reduction of 87.1% in the peak heat release rate, as well as an 86.6% reduction in the total heat release. Additionally, when utilized as a reinforcement in poly(vinyl alcohol) (PVA) films, SCNC demonstrated a substantial rise in yield strength (from 62.3 to 94.8 MPa) and Young's modulus (from 2.7 to 4.4 GPa) of the PVA films. Furthermore, the incorporation of SCNC into composites increased the thermal stability while maintaining the high transparency (with light transmission higher than 84%), which has good potential for application in the electronic packaging field. Highlights SCNC were successfully prepared from waste cotton using DES. Extracted S CNC were characterized using TEM, FTIR, XRD, TGA and MCC. SCNC enhanced the yield strength and thermal stability of PVA composites. Transparent and mechanically robust PVA‐based nanocomposites were created.