Preparation, Characteristics, and Application of Bifunctional TiO₂ Sheets

TiO₂ is a high-reflectance material for preparing sheets during dry reagent chemical tests in detail. In this study, bifunctional TiO₂ sheets with diffusive and reflective properties were prepared using TiO₂ microspheres (particle size 2-3 µm) and cellulose acetate (CA). Factors such as the CA dosage, water content, mixing time, and the choice of surfactant were investigated. The structure and properties of the bifunctional TiO₂ sheets were characterized by thermogravimetry and differential thermal analysis (TG-DAT), scanning electron microscopy (SEM), dynamic contact angle test and reflectance spectroscopy. By studying the above experimental results, it was concluded that the most optimal preparation conditions for preparing the bi-functional TiO₂ sheets under natural drying conditions were as follows: the mass ratio of CA to TiO₂ microspheres was 0.05:1; Triton-100 was used to improve the diffusion performance of the bifunctional sheets, after mixing for 5 h and coating. The light reflectivity of the bifunctional TiO₂ sheets in the 420 to 800 nm range was higher than 90%. Serum diffused in the bifunctional TiO₂ sheets reacted in the reagent sheets and formed uniform colorful spots. Considering the repeatability of spot proportion and light reflectivity, the sheet offered a uniform serum diffusion and good repeatability. So, the bifunctional TiO₂ sheets are nominated as a promising material for dry chemical diagnostic reagents.