An attractive attempt: Facile and direct adhesive of cellulose substrates using inorganic metal salt through partial welding

The development of cellulose-substrate remedies remains a technological challenge owe to their inability to self-heal and excessive dependence on petroleum-based adhesives, which is further hindered by the significant drawbacks of commercially unavailable welding materials and inconvenient manipulation. We herein describe a cellulose-substrate bonding technique achieved through partial dissolution using a low dosage of ZnCl2 aqueous solvent (ZS) and its dissolved cellulose (ZDC) gel as adhesives. This method demonstrates strong joint areas between strips without any failure, while shrinkage in the diffusion area remains the main cause of breakage. This shrinkage phenomenon can be alleviated by using ZDC instead of ZS, due to the water retention of hydrophilic hydroxyls on the macromolecular chains of dissolved cellulose. The well-maintained tensile strength of the ZDC-bonded strip (5.0% lower than the control) indicates that partially dissolved cellulose fills gaps between fibers, providing evidence for a mechanical interlocking adhesive mechanism in strip connections. ZDC gels exhibit favorable adhesive behavior for hand-sheets, art paper, and corrugated board, with welded joints demonstrating robust mechanical performance even after soaking in water for 6 h.