Oil-Soluble Ultraviolet-Absorbing Carbon Dots Dispersed in Polyethylene Films as Antiaging Materials

Ultraviolet (UV) absorbents are widely used in coatings and polymers owing to their remarkable absorbance of UV irradiation. As a new type of organic UV absorbent, carbon dots (CDs) have presented outstanding UV absorption properties. However, the use of water-soluble reactants in the synthesis process of most CDs makes them easy to dissolve in water, which is not conducive to their use in the field of thin films. In this paper, we report an effective hydrothermal method to prepare three-component carbon dots (Im-CDs) from sodium citrate, ethylenediamine, and imidazole and then modify the surface to obtain the final product (AOT-CDs) by docusate sodium. The AOT-CDs exhibited a strong UV absorption capacity to UVA and UVB but a transmittance in the visible region both in solution and in polymers. In addition, docusate sodium is regarded as a suitable surface modifier to transfer Im-CDs from water to various organic solvents. When the excellent oil-soluble AOT-CDs are applied to a polyethylene film, the properties of the films, including the efficiency of UV shielding, mechanical property, and aging time, can be effectively tuned by changing the concentration of AOT-CDs. Our full-band UV-shielding films with CDs show no obvious degradation in the process of accelerated UV aging for dozens of days. Due to their ecofriendliness and good chemical and thermal stability in films, AOT-CDs are expected to become competitive candidates for next-generation UV absorbents.