Synthesis of Oil-Soluble Broad-Spectrum UV-Absorbing OA-CDs via a Multistep Hydrothermal Method and Their Application in Paints

Ultraviolet (UV) absorbers are incorporated into coatings primarily to augment their resistance to UV radiation, thereby safeguarding the substrate from damage inflicted by UV rays. In this investigation, oil-soluble carbon dots (OA-CDs) were synthesized through repeated hydrothermal methods, which enabled them to have excellent UVA and UVB absorption, thus improving the poor UV absorption performance of oil-based carbon dots. When added to epoxy resin paints, they can achieve 96% UV absorption. Since OA-CDs are nanomaterials with a large number of carbon chain ligands, adding them to the paint improved the glass transition temperature, hardness, tensile strength, etc. of the epoxy resin. In the accelerated aging test, the effect of OA-CDs as a UV absorber added to epoxy resin can approach that of the commercial UV531. Moreover, owing to the abundant surface ligands of the OA-CDs, in acid–base salt experiments, the epoxy resin exhibits enhanced resistance to environmental changes compared to commercially available UV absorbers. Due to their outstanding performance, OA-CDs have the potential to emerge as a novel oil-soluble UV absorber suitable for applications in film, coatings, and related fields.