Preparation and properties of transparent superhydrophilic coatings based on copolyester emulsion and polyethyleneimine

In this work, an environmentally friendly copolyester with water dispersibility is used as the base material. After the incorporation of a curing agent and a silane coupling agent as additives, a superhydrophilic coating was successfully prepared. The resulting mixed solution was applied to substrates using a spraying technique, followed by thermal curing to achieve the desired superhydrophilic properties. The physical and chemical characteristics of the superhydrophilic coating were thoroughly characterized and evaluated. The results demonstrate effective modification of the coating. Water droplets spread completely across the coating surface within 1 s, achieving a contact angle of less than 10°. The coating exhibited outstanding physical and chemical performance in various tests, including impact resistance, hardness, high-temperature resistance, water resistance, and UV aging. Furthermore, the coating demonstrated good adaptability and stability on different substrates. It could be directly applied to surfaces such as iron sheets, PET film, glass, and glass slides. In this study, iron sheets were selected as the substrate for the superhydrophilic coating to ensure that the mechanical property testing requirements of the coating could be adequately met. The superhydrophilic coating prepared in this paper has superhydrophilicity (water contact 6.384°), high light transmittance, stability and self-cleaning function, and has great application potential in hydrophilic modification of PET films, coating of multifunctional medical equipment, etc.