Adhesive hydrogels are relevant for a variety of applications, such as in implants, tissue repair, for underwater sensoring, or marine repair works. To this end, it is essential to provide the necessary chemical properties to the hydrogel for it to be able to adhere to the desired surface. Liu and co-workers demonstrated this by combining alkylcatecholcontaining copolymers with CS to obtain a tough double network hydrogel. The catechol unit promoted selective and improved adhesion towards wet biological tissue as well as CS or gelatin surfaces, rather than plastic, metal, or rubber. Since the fracture energy of the evaluated hydrogel (Γ = 6.6 kJ/m 2 ) lied in the same range as the one of porcine skin (Γ = 1.6 kJ/m 2 ), the latter was primarily used to quantify the hydrogel's adhesiveness in a lap shear adhesion test. The hydrogel showed an adhesion strength of 180 kPa for 20 cycles, an adhesion energy of 1.6 kJ/m 2 , which decreased to 1 kJ/m 2 , when the porcine skin-hydrogel composite was immersed for 6 h in water. With an aqueous solution (pH = 8), the hydrogel's adhesion energy was further weakened to facilitate dettachment of the hydrogel from the porcine skin leaving it damage-free. These results showed how the fracture and adhesion energy can ben used as quantitative tools, their change either allowing the gel removal or promoting strong surface bonding.