Zeolite-Based Antifogging Coating via Direct Wet Deposition

Abstract

Zeolites are strongly hydrophilic materials that are widely used as water adsorbents. They are also promising candidates for antifogging coatings; however, researchers have yet to devise a suitable method for coating glass substrates with zeolite-based films. Here, we report on a direct wet deposition technique that is capable of casting zeolite films on glass substrates without exposing the glass to highly basic solutions or the vapors used in zeolite synthesis. We began by preparing cast solutions of pure silica zeolite MFI synthesized in hydrothermal reactions of various durations. The solutions were then applied to glass substrates via spin-on deposition to form zeolite films. The resulting zeolite MFI thin films were characterized in terms of transmittance to visible light, surface topography, thin film morphology, and crystallinity. Wetting and antifogging properties were also probed. We found that hydrophilicity and antifogging capability increased with the degree of thin film crystallinity. We also determined that the presence of the amorphous silica in the thin films is critical to transparency. Fabricating high-performance zeolite-based antifogging coatings requires an appropriate composition of zeolite crystals and amorphous silica.

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

“…22,23 The second class requires a zeolite suspension with fully grown crystals, which involves dip coating, 24,25 spin-on deposition, 26−29 or spray deposition. 14,30 The second class avoids the need to expose the substrate to a high-pH environment during zeolite crystal growth, thereby making it possible to deposit zeolites on silicon wafers, 29,31,32 glass substrates, 33,34 and aluminum alloy. 35,36…”

Effect of adding carboxymethyl cellulose, zeolite and microcrystalline cellulose on the optical and mechanical properties of latex composite films

“…a (Latex), latex 5 mL to water 5 mL, b (CMC), CMC 0.02 g to water 10 mL c (MCC), MCC 0.02 g to water 10 mL, d (Zeolite), Zeolite 0.05 g to water 10 mL e (MCCB), MCC 1.00 g to water 10 mL-NaOH(12%w/v) 30 mL . The bands of functional groups in latex were observed at 1200 cm -1 , 1450 cm -1 , 1700 cm -1 , 2900 cm -1 and 3300 cm -1 indicate C-O stretching vibrations, -CH2 bending vibrations, C=O stretching vibrations, C-H stretching vibrations and O-H stretching vibrations, respectively [2]. The band at 1600 cm -1 are attributable to C=O asymmetrical stretching vibrations that relate to carboxymethyl cellulose (Figure 2(a)) [3].…”

“…Inorganic filler materials (e.g. zeolites and halloysite nanotubes) have been widely used in the preparation of composite films [2][3][4]. Addition of zeolite improves the mechanical properties both the tensile strength and Young's modulus of latex composite film.…”

Toward Long-Lasting Low-Haze Antifog Coatings through the Deposition of Zeolites

“…Despite being broadly used for catalysis, 33−36 adsorption, 37,38 membranes for molecular separations 39−44 and membrane reactors, 45−47 thin films for electronic devices, 48−52 gas detection, 53,54 anticorrosion, 55−57 antireflection, 58 and photocatalysis, 59 there are only few reports on using zeolites as antifog coating. 29,60,61 The key limitation is the deposition method of zeolites on glass substrates. The welldeveloped methods used in the fabrication of zeolite films or membranes include in situ growth, 52,62,63 seeded growth, 64,65 dip coating, 66,67 and dry-gel conversion.…”

“…29,48,51,61 This method reduces the time for the substrate being exposed to the high-pH cast solutions to less than an hour. We have successfully used the direct wet deposition to achieve antifog coatings based on zeolite MFI 29 and zeolite CHA; 61 importantly, the relationships between the properties of the cast solutions and the quality of the resulting coating remain unclear.…”