Wetting Properties and Thin-Film Quality in the Wet Deposition of Zeolites

Zeolites are microporous crystalline materials widely used in catalysis and adsorption applications. The fabrication of zeolite thin films and membranes has also opened up the possibility of using zeolites in electronic devices and membrane separations. The existing approach to growing zeolite films involves exposing the substrate to a high-pH environment; however, this process is applicable to only specific types of substrates. Our group has developed the direct wet deposition of zeolites via ultrasonic nozzle spray deposition to address this issue; however, the relationship between wetting properties and thin-film quality has yet to be investigated. In this study, we prepared zeolite CHA (Si:Al:P = 3:10:20) suspensions using different solvents and surfactants in various concentrations. We then examined the relationships among the composition of the cast solution, their wetting behavior on the glass substrate, and the uniformity of the resulting thin films. We found that using ethanol as a solvent with zeolite crystals in low concentrations with added surfactant yielded zeolite films of high quality. We were also able to produce low-haze zeolite coatings on glass. The zeolite coatings with high hydrophilicity and adsorption capacity presented excellent antifogging capability.