Molecular Hyperpolarization-Directed Photothermally Enhanced Melanin-Inspired Polymers

Constructing a donor–acceptor (D–A) structure is a common strategy to change the polarizability and dipole moment of local molecules and induce the re-hybridization of molecular orbitals, which could lead to the reduction of the bandgap and promote the transfer of electrons. Although such a strategy has been successfully applied in organic optoelectronics with well-defined molecular structures, very limited progress has been reported for polymers with disordered and complex structures. In this work, we strived to employ this strategy to manipulate the light absorption and photothermal behaviors of melanin-inspired, polydopamine (PDA), a typical kind of electron-rich molecular systems by involving a strong receptor unit, trichloroisocyanuric acid through covalent connection to construct D–A pairs. This design could decrease the bandgap and improve the optical absorption by orbital re-hybridization, which has been carefully verified by detailed spectral analysis and simulated calculation. The remarkable photothermal performances present promising potential in photothermal Marangoni actuators and solar power generation and provided new opportunities for the rational design of the microstructure of melanin.