Hydrophilic nano-SiO 2 /PVA-based coating with durable antifogging properties
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Hydrophilic nano-SiO2/PVA-based coating with durable antifogging properties Guoqiang Wu, Yuling Yang, Yongtong Lei, Dapeng Fu, Yuchao Li, Yanhu Zhan, Jinming Zhen, Mouyong Teng
Ó American Coatings Association 2020 Abstract Hydrophilic SiO2/poly(vinyl alcohol) (PVA) coating prepared by solution blended method showed high light transmittance and durable antifogging performance. The effects of SiO2 content and pH value of SiO2 suspension on the morphology and properties of hydrophilic coating were studied by Fourier transform infrared spectroscopy, scanning electron microscopy, atomic force microscopy, contact angle test, ultraviolet visible light spectrophotometer, and antifogging test. Results showed that the PVA had good compatibility with nano-SiO2 because of the formation of Si–O–C chemical bond at the interface between nano-SiO2 and PVA. When prepared at pH = 7, SiO2/PVA coatings (SiO2/PVA mass ratio of 0.8) were hydrophilic, with a water contact angle of 22.9°, and exhibited papilla-like surface features (RMS = 7.6 nm). Polyethylene (PE) samples coated with this SiO2/PVA film exhibited a light transmittance of up to 90%, between 560 and 700 nm, and remained fog-free for more than 1 month after exposure to water at 60°C (QB/T 4475-2013 standard). Water-resisting and wear-resisting tests revealed that antifogging coatings demonstrated excellent mechanical properties. Keywords Hydrophilic coating, Papilla-like structures, High transmittance, Durable antifogging
Electronic supplementary material The online version of this article (https://doi.org/10.1007/s11998-020-00338-z) contains supplementary material, which is available to authorized users. G. Wu, Y. Yang, Y. Lei, D. Fu, Y. Li, Y. Zhan, J. Zhen, M. Teng (&) School of Materials Science and Engineering, Liaocheng University, Liaocheng 252000, China e-mail: [email protected]
Introduction Fogging occurs when water molecules condense as discrete droplets with diameters larger than 190 nm or half of the shortest wavelength (380 nm) of visible light.1 This phenomenon is harmful to optical materials and analytical and medical instruments, such as eyeglasses,2 goggles, solar cells,3 face shields, binoculars, microscopes,4 and laparoscopes.5 Fogging is also common in agricultural greenhouses where a polymer film, such as polyethylene (PE), is used as a barrier to protect growing plants.6 The occurrence of fogging results in a number of side effects, including poor film clarity and reduced light transmittance. Several research groups have developed polymer films with antifogging performance by depositing hydrophilic coatings.7–12 An efficient way to prevent fog is to increase the surface energy that can form a hydrophilic surface for polymer films. Water drops lying on a (super)hydrophilic surface spread across it to form a transparent and continuous thin film of water. The resulting layer of water allows for the incident light to pass through it without being scattered, thus attaining the antifogging effect.13–16 So far, two main strategies have been explored to p
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