Light Harvesting Modulation of Melanin-Like Polymers via Thiol-Michael “Click” Chemistry

"Click" chemistry, featuring high selectivity, efficiency, and modularity, has been regarded as a powerful tool to construct and engineer macromolecular materials with complex and disordered structures. In this work, we reported our first effort to use the thiol-Michael "click" chemistry to tune the energy structure and light harvesting behavior of melanin-like polymers by "clicking" mercaptotetrazole (MT) building blocks into the complicated polydopamine (PDA) networks, successfully acquiring a series of melanin-like nanoparticles with boosted light absorption and photothermal effect. A comprehensive characterization by density functional theory (DFT) stimulation, spectral analysis, cyclic voltammetry, and transient absorption demonstrated the energy bandgap reduction and light harvesting enhancement of those MT-doped PDA samples. The resulting polymers also exhibited excellent photothermal effect, which could be applied in efficient electric energy generation through photothermoelectric conversion and solar desalination application. This study provided new opportunities to regulate the functions of a complex bioinspired macromolecule system through "click" chemistries.