Mussel-inspired multi-functional adhesive for metal flexographic printing plates: Superior metal and polymer adhesion, strength, toughness, and long-lasting durability

Flexographic printing plates, which are typically composed of a metal substrate, an adhesive layer, and a poly(vinyl alcohol) (PVA) photosensitive layer, are essential for achieving high-resolution patterns in flexographic printing technology. The adhesive layer, serving as the bonding interface between the metal and PVA layers, must exhibit strong adhesion to both metal and polymer surfaces, along with high toughness, mechanical strength, solvent resistance, and durable adhesion to meet the mechanical and chemical requirements of flexographic printing technology. Herein, inspired by the structure of mussel foot silk protein, this study integrates carbon–carbon double bonds, catechol, alcohol hydroxyl, and amino ester groups into a single polymer chain via a two-step reaction. Benefits to its rigid-flexible cross-linked network, the obtained adhesive exhibits good strength, modulus, and toughness. Specifically, its tensile strength, tensile modulus, elongation at break, and impact strength are 1.70 MPa, 0.85 GPa, 19.3 %, and 2.97 kJ/m 2 , respectively. Furthermore, the adhesive achieves a 180° peel strength of 2.26 N/mm with tinplate and 3.89 N/mm with flexographic printing plates. Notably, after 7 days of immersion in water, ethanol, and dimethylformamide, the 180° peel strength retention rate was as high as 96.9 %, 96.2 %, and 93.9 %, respectively. After being stored at room temperature for 28 days, the 180° peel strength retention rate reaches up to 98.3 %, highlighting its long-lasting durability. This mussel-inspired group integration strategy provides a straightforward and efficient approach for developing high-performance multi-functional adhesives, with significant potential for advancing flexographic printing.