An Epoxy Adhesive Mimicking the Mussel Mucin Used for Bonding Under Seawater

With rising interest in various offshore equipment, bridges, and marine engineering, it is necessary to develop an epoxy resin adhesive that can cure quickly under seawater and has high bonding performance. In this paper, through mimicking mussel adhesive proteins, a biomimetic epoxy resin is designed and prepared for seawater adhesion. A mussel dopamine-like structure with cashew phenol and catechol as the main structure is prepared by the Mannich reaction, and the amino acids in mussel adhesive protein are simulated by the addition of decamethylene diamine. The results show that the adhesive has higher seawater bonding strength (17.65 MPa) and tensile strength (30.31 MPa) under the condition of seawater solidification. The cross-section morphology of the adhesive is still a typical ductile fracture due to the adhesive retaining the toughened properties of the cashew phenol structure, while the catechol structure provides a stronger bonding ability. The apparent activation energy is 45.22 kJ mol^-1 indicating in a high curing activity. The ions in seawater can participate in the bonding process of the adhesive, and non-covalent bonds can be formed in the process. The construction strategy that mimics the mussel adhesive protein structure can also be used to design other seawater adhesives.