Synthesis of Transparent ZnO–TiO2 and Its Nanocomposites for Ultraviolet Protection of a Polyethylene Terephthalate (PET) Film

The goal of this research was to investigate the effects of ZnO–TiO2 and its nanocomposites, on the physical, mechanical, and ultraviolet protection of polyethylene terephthalate (PET). Exposure to ultraviolet (UV) rays is a major cause of the degradation of the quality and optical properties of materials in addition to skin cancer; therefore, research on UV-blocking materials that are safe and have fewer side effects than currently available products is being actively conducted. In this study, a material with UV-blocking capability was synthesized while ensuring the transparency of ZnO and TiO2. ZnO–TiO2 and its various composites were successfully synthesized via a hydrothermal method followed by ball milling and their properties were systematically analyzed by using scanning electron microscopy, X-ray diffractometry, Fourier-transform infrared spectroscopy, and water contact angle measurements. Furthermore, a simple dip-coating method was employed to prepare transparent polyethylene terephthalate (PET) films coated with the composites, which were subsequently investigated for UV-blocking properties by exposing them to UV irradiation. The hydroxyl groups of ZnO and TiO2, as representative inorganic sunblock components, were removed by using 3-chloropropyl trimethoxy silane as a coupling agent to improve their wettability in an organic solvent as well as their dispersibility and stability. The addition of a small amount of Tinuvin® allowed the hybrid organic and inorganic components to exhibit transparent UV-blocking characteristics, with a UV transmittance of ≤20% and 90% visible transmittance. These results, thus, serve as a basis for contributing to applications in the field of packaging, health, and hygiene industries.