Mechanochemical Synthesis of Linear Melanin-like Polymer with Tunable Physical Properties

Polydopamine-based melanin-like materials have been widely used in the fields of ultraviolet (UV) shielding, solar desalination and anti-inflammatory treatment owing to their unique physical properties. The well-established synthesis of polydopamine nanoparticles involves the oxidative polymerization of dopamine-derived monomers, resulting in cross-linked nanostructures with high complexity and heterogeneity. Therefore, the controlled synthesis of polydopamine-based melanin-like materials with well-defined structures and predictable properties remains challenging. Herein, we propose a mechanochemical Suzuki polymerization approach for the synthesis of linear melanin-like polymers with tunable physical properties. Compared with polydopamine nanoparticles, the mechanochemical approach offers a more flexible chain-like structure, thereby enhancing its antioxidant performance. Furthermore, this approach also enables the preparation of a melanin-like alternating copolymer that exhibits green fluorescence owing to its pi-conjugated structure. This study not only offers opportunities for exploring novel synthetic melanin materials, but also provides new insights into the structure-function relationships of polydopamine-based materials.