Non‐Covalent Self‐Assembly and Covalent Polymerization Co‐Contribute to Polydopamine Formation

Abstract Polydopamine is the first adhesive polymer that can functionalize surfaces made of virtually all material chemistries. The material‐independent surface modification properties of polydopamine allow the functionalization of various types of medical and energy devices. However, the mechanism of dopamine polymerization has not yet been clearly demonstrated. Covalent oxidative polymerization via 5,6‐dihydroxyindole (DHI), which is similar to the mechanism for synthetic melanin synthesis, has been the clue. Here, it is reported that a physical, self‐assembled trimer of (dopamine) 2 /DHI exists in polydopamine, which has been known to be formed only by covalent polymerization. It is also found that the…