Highly water- and oil-resistant cellulose paper fabricated through partial dissolution and regeneration based on...

Developing renewable and biodegradable paper packaging materials as alternatives to traditional plastic packaging materials has been a hot topic in contemporary society. However, the primary disadvantage of paper in comparison to plastic is its poor barrier properties and low wet strength, causing a propensity for tearing when exposed to moisture. In this research, a facile and cost-effective deep eutectic solvent (DES, ZnCl₂/H₂O/HCOOH) system was employed to partially dissolve the ready-made paper at ambient temperature, followed by a regeneration process in seven different coagulation baths to produce partially regenerated cellulose paper. The barrier properties of the regenerated paper were tailored by the deliberate modulation of coagulation-bath polarity. The type of coagulation medium was found to significantly influence the morphology and crystallinity of the regenerated cellulose, thereby affecting the internal structure and properties of the partially regenerated paper. Remarkably, the paper regenerated in ethylene glycol showed a light transmittance of 60 %, high dry and wet strength of 56 MPa and 22 MPa, respectively, a low water vapor transmission rate of 62 g·m^-2d^-1, and superior oil repellency with a kit value of 12/12. The excellent water- and oil-resistant performance makes it an ideal material for food packaging. In a word, this work presents a simple approach and novel idea for fabricating water- and oil-proof and environmentally-friendly paper packaging.