Synthesis of yellow and green carbon quantum dots and study on the UV resistance of finished cotton fabrics

In order to effectively protect the skin from ultraviolet (UV) radiation damage, this study focuses on the field of UV protection. Using o-phenylenediamine isomers and 2,2-bis(hydroxymethyl)propionic acid as carbon sources, yellow and green fluorescent carbon quantum dots (CQDs-Y and CQDs-G) were synthesized via a one-step hydrothermal method. The CQDs water solution was directly coated on the surface of cotton fabric to impart UV protection properties. Polyvinyl alcohol (PVA) was used as a coating to cover the surface of the cotton fabric treated with CQDs, and its UV protection performance and water washing durability were tested. The results showed that the prepared CQDs had a quasi-spherical structure with sizes ranging from 3 to 5 nm, and contained multiple aromatic structures and hydrophilic groups, exhibiting good water solubility. The CQDs showed excellent absorption ability in the UV region, emitting yellow and green fluorescence under UV lamp irradiation, demonstrating wavelength-independent photoluminescent behavior. The cotton fabric treated with phenylenediamine isomers and 2,2-bis(hydroxymethyl)propionic acid exhibited higher UV protection factor, with an UV protection ability of 19.95 after coating with 5 mL PVA. It also showed significantly improved water washing durability compared to the original fabric, and had better moisture permeability, meeting the UV protection requirements for cotton fabric.