High-Light-Transmittance and Low-Haze Antifog MFI Zeolite Films Fabricated by Solvothermal Secondary Growth

Preventing the appearance of fog on transparent glass is an important issue not only in our daily lives but also in scientific research and clinical diagnosis. A zeolite molecular sieve with MFI-type structure was identified as a very promising antifog material. In this work, MFI zeolite films with different microstructures were prepared by the solvothermal secondary growth method using diols including ethylene glycol (EG), diethylene glycol (DEG), triethylene glycol (TEG), and tetraethylene glycol (tEG) as solvents. The elimination mechanism of new MFI twin crystals was demonstrated based on scanning electron microscopy (SEM), X-ray diffraction (XRD), and transmission electron microscopy (TEM) characterizations of the resulting films and the mother solutions. The twin-free MFI films with b-axis preferred channel orientation exhibited both higher light transmittance and lower haze compared with the a-&b-mix-oriented film. The employment of diol solvents facilitated the generation of a surface Si–OH group on the films, leading to the improvement of film hydrophilicity. By taking advantages of the high transparency and hydrophilicity, the b-oriented MFI films synthesized on glass substrate achieved good antifogging performance.