Polycondensation-Involved Melanin-like Polymers for Enhanced Solar Energy Utilization

Abstract

Polydopamine (PDA) and poly­(5,6-dihydroxyindole) (PDHI), both typical representatives of melanin-like polymers, are emerging as promising kinds of photothermal functional materials with a similar polymeric structure. However, the chaos of the microstructure formed by free radical polymerization of monomers still hinders the efficient regulation of their photothermal performances. Herein, we introduced condensation polymerization between aldehydes and the 5,6-dihydroxyindole (DHI) monomer during the free radical polymerization process to construct more D–A pairs, which can regulate the energy structures and reduce the optical band gaps within the macromolecules. In this way, a series of PDHI nanoparticles (NPs) with enhanced light absorption of visible light and photothermal properties were successfully prepared and were used for solar power generation and water desalination with 91.8% evaporation efficiency. It was believed that this work could provide new opportunities for the structure–function tailoring of bioinspired materials and further expand their applications for high-efficiency solar energy utilization.

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

“…To assess the solar evaporation ability quantitatively, the mass change of seawater was recorded. The evaporation rate of NPDA-3@PES was calculated to be 1.97 kg m –1 h –1 in Figure h, and the value was higher than that of PDA-0@PES of 1.78 kg m –2 h –1 and many other kinds of melanin-like polymer-based evaporation devices reported in previous literatures. ,, In order to test the seawater desalination performance, the concentrations of four main metal ions, including Na + , Mg 2+ , K + , and Ca 2+ , were evaluated before and after desalination by the inductively coupled plasma spectroscopy (ICP-OES), respectively (Figure i). The metal ion concentrations sharply decreased approaching to the concentration of deionized water.…”

“…Nevertheless, the disordered and undefined structure of PDA hinders the effective adjustment of their energy bandgap and light harvesting performance, and the modular and efficient chemistries are highly desirable. In our previous work, regulating the energy structure and light absorption of melanin-like polymers has been realized by increasing electron donor–acceptor (D–A) microstructures within macromolecular systems. − However, most typical electron D–A constructing strategies usually required sophisticated organic synthesis by involving strong oxidants and bases, probably resulting in the formation of structural defects. For those cases, the lack of robust and suitable chemical tools for the structural regulation of melanin-like polymers could hinder the establishment of the structure–function relationship in complex and disordered bioinspired macromolecules.…”

Melanin-Inspired Composite Materials: From Nanoarchitectonics to Applications

“…In addition to the all melanin composites, melanin could also be integrated with other organic building blocks to enable enhanced performance by physical blending and predoping, such as near-infrared (NIR) light absorption, antioxidation, hydration-dependent conductivity, biocompatibility, and render tremendous application. ,− For instance, tobramycin (TOB) is a broad-spectrum antibiotic that contains an amino group and can be copolymerized with dopamine monomers through Michael addition reaction . Antibiotics endow nanoparticles with antibacterial properties, and the excellent light adsorbing properties of PDA make it a possible photothermal composite material for solar distillation. − …”

Nature-inspired safe and efficient hair dyes: beyond the traditional hair dyes

“…It has been extensively shown that constructing the donor–acceptor (D–A) structures is a typical strategy for modulating the light absorption capacity in polymers. 103 The PDA system usually includes non-cyclized DA, DHI, indole-5,6-quinone (IQ), and oligomers of these units. Among them, IQ provides conjugate structures in PDA systems to achieve a wide range of light absorptions.…”

“…The chemical connection between DHI and electron-rich IQ has also been regarded as electron donor–acceptor pairs (D–A pairs), which could regulate the energy gap and light absorption properties of the PDA system. 63,103–105 Therefore, the introduction of electron acceptors could further contribute to the construction of D–A pairs with DHI, IQ, and their oligomers in the PDA system, which would induce molecular rehybridization and thus manipulate the energy structure and optical absorption (Fig. 9).…”