Characterization of Multilayer Anti-Fog Coatings

Abstract

Fog formation on transparent substrates constitutes a major challenge in several optical applications requiring excellent light transmission characteristics. Anti-fog coatings are hydrophilic, enabling water to spread uniformly on the surface rather than form dispersed droplets. Despite the development of several anti-fog coating strategies, the long-term stability, adherence to the underlying substrate, and resistance to cleaning procedures are not yet optimal. We report on a polymer-based anti-fog coating covalently grafted onto glass surfaces by means of a multistep process. Glass substrates were first activated by plasma functionalization to provide amino groups on the surface, resulting in the subsequent covalent bonding of the polymeric layers. The anti-fog coating was then created by the successive spin coating of (poly(ethylene-maleic anhydride) (PEMA) and poly(vinyl alcohol) (PVA) layers. PEMA acted as an interface by covalently reacting with both the glass surface amino functionalities and the PVA hydroxyl groups, while PVA added the necessary surface hydrophilicity to provide anti-fog properties. Each step of the procedure was monitored by XPS, which confirmed the successful grafting of the coating. Coating thickness was evaluated by profilometry, nanoindentation, and UV visible light transmission. The hydrophilic nature of the anti-fog coating was assessed by water contact angle (CA), and its anti-fog efficiency was determined visually and tested quantitatively for the first time using an ASTM standard protocol. Results show that the PEMA/PVA coating not only delayed the initial period required for fog formation but also decreased the rate of light transmission decay. Finally, following a 24 hour immersion in water, these PEMA/PVA coatings remained stable and preserved their anti-fog properties.

Zwitterionic polymer brush coatings with excellent anti-fog and anti-frost properties

“…For instance, a polymer-based anti-fog coating covalently grafted onto glass surfaces by means of a multistep process that includes spin coating of (poly(ethylene-maleic anhydride) (PEMA) and poly(vinyl alcohol) (PVA) layers has been reported. 1 The results showed that the PEMA/PVA coating not only prolonged the initial period required for fog formation, but also decreased the rate of light transmission decay. Additionally, these PEMA/PVA coatings remained stable and their anti-fog properties were preserved after immersion in water for 24 h. Moreover, Lee and co-workers demonstrated that a zwitter-wettable surface prepared by layer-by-layer (LbL) assembly of PVA and poly(acrylic acid) (PAA) functionalized with poly(ethylene glycol methyl ether) (PEG) segments afforded a significantly enhanced anti-fog and anti-frost properties.…”

“…This may lead to many problems for the use of eyeglasses, windows, mirrors, goggles, and optical instruments. [1][2][3][4] Over the last few decades, an extensive research studies have been reported to prevent the formation of fog and frost on solid surfaces by different approaches including superhydrophobic coatings, 5-7 superhydrophilic coatings 8,9 and combinations of both hydrophilic and hydrophobic properties in the coating. [10][11][12][13][14][15] Hydrophilic surfaces that have a water contact angle of less than 5 o exhibit excellent anti-fog properties because they allow water droplets to spread uniformly to form a thin water film, which reduces light scattering.…”

Fogging Control on LDPE/EVA Coextruded Films: Wettability Behavior and Its Correlation with Electric Performance

“…There have been some attempts to substitute the use of surfactants. Several hydrophilic compounds have been developed as non-migratory agents, including silicon-based molecules, metallic oxide nano-particles and blends with hydrophilic polymers, among others [1,6,7,8,9,10,11,12]. Current technology that increases the wettability of non-polar polymers using surfactants is preferred by the industry, because it implies minor technological difficulties and lower costs without alterations in the bulk properties of the polyolefin [13,14].…”

Pembuatan Semak (Semprotan Anti Keruh) Sebagai Alternatif Lapisan Pencegah Kekeruhan Pada Kacamata

“…Permukaan dikatakan tidak keruh jika cairan menyebar merata hingga ke seluruh permukaan tanpa pembentukan tetesan (droplet) sehingga hamburan cahaya tidak terhambat [2]. Ketika cairan menyebar di atas permukaan tanpa pembentukan droplet, permukaan dikatakan hidrofilik.…”