Photothermal and robust supramolecular soft material crosslinked via dinuclear heterodentate coordination

Efficient, green, and intrinsic solar-photothermal conversion elastomers are crucial for sustainable energy solutions. However, the traditional elastomer/solar-absorber composites suffer from poor compatibility, resulting in a low solar-photothermal efficiency and suboptimal mechanical properties. Herein, chitosan was selectively oxidized and blended with XNBR emulsion, followed by the incorporation of Fe₂(SO₄)₃ and CuSO₄ to create a dinuclear heterodentate coordination structure as a novel crosslinked network within the XNBR composites (XNBR/OCTS/Fe₂(SO₄)₃/CuSO₄). Remarkably, without sulfurization, the composite achieved a tensile strength of 12.7 MPa and an elongation at break of 955%. The carbonization of OCTS, along with the in situ reduction of Cu nanoparticles through interface reactions facilitated the XNBR/OCTS/Fe₂(SO₄)₃/CuSO₄ composite to possess a significantly enhanced intrinsic solar-photothermal conversion efficiency. Under 1 min infrared irradiation with 100% elongation, the localized temperature of the composite increased from 27 °C to 137 °C. For the first time, carbonized OCTS was utilized to significantly improve the photothermal conversion, deviating from its traditional role as a polysaccharide-based substrate. Additionally, XNBR/OCTS/Fe₂(SO₄)₃/CuSO₄ exhibited strong antibacterial activity against E. coli and S. aureus, and the XNBR matrix could be recovered through acidolysis of the OCTS owing to the dissociation of the dinuclear heterodentate coordination network. This approach provides a valuable framework for designing high-performance intrinsic solar-photothermal conversion elastomers using sustainable green resources.