Transparent Composite Films Showing Durable Antifogging and Repeatable Self-Healing Properties Based on an Integral Blend Method

Design of Abrasion-Resistant, Long-Lasting Antifog Coatings

Fog formation is a common challenge for numerous applications, such as food packaging, mirrors, building windows, and freezer/refrigerator doors. Most notably, fog forms on the inner surfaces of prescription glasses and safety eyewear (particularly when used with a mask), face shields, and helmet lenses. Fogging is caused by the distortion of light from condensed water droplets present on a surface and can typically be prevented if the surface static water contact angle (θ) is less than ∼40°. Such a low contact angle can be readily achieved by either increasing the substrate surface energy or by engineering surface nanotexture. Unfortunately, such nanotexture can be readily damaged with use, while high surface energy substrates get covered with low surface energy foulants over time. Consequently, even with numerous ephemeral antifog coatings, currently there are no commercially available, durable, and permanent antifog coatings. Here we discuss the development of a new class of high-performance antifog coatings that are abrasion-resistant and long-lasting. These polyvinylpyrrolidone-based coatings, designed based on the classical Ratner-Lancaster wear model, dramatically outperform the base polymer, as well as all tested commercially available antifog coatings. Specifically, these coatings exhibit a > 400% increase in fogging time compared to base polymer, a > 50,000% increase in wear resistance, and excellent long-term antifog performance. The developed coatings also significantly outperformed all tested commercially available antifog coatings in terms of their antifog performance, wear resistance, and long-term cyclical performance. Additionally, the key design strategies employed here─incorporation of toughening agents and hydrophilic slip additives─offer a new approach to developing high-performance, durable antifog coatings based on other well-known antifog polymers.

Fabrication of Robust Carbon Dots Containing Coatings with UV-Shielding, Light Conversion, and Antifogging Multiple Functions

Although a wide variety of single-function coatings have been successfully developed, the integration of multiple functions onto a single coating has remained an immense challenge in the field. Here, we report a simple room-temperature fabrication of robust coatings with UV-shielding, light conversion, and antifogging functionalities. The addition of glutaraldehyde (GA) molecular cross-linker and carbon dot (CD) nanocross-linker with light conversion function to poly(vinyl alcohol) (PVA) resulted in the formation of robust spatial structures of coatings. The fluorescence intensity tests demonstrated that the coatings had an excellent ability to absorb and convert ultraviolet light into blue-violet light. Both cold-warm and hot-vapor tests showed that the coatings had excellent antifogging performance. To our surprise, no creases were observed after coatings were immersed in water for 1 month, indicating that these are much stronger than those reported so far. The 8H pencil hardness and wear resistance attested to their excellent mechanical properties. The current preparation method can be operated at ambient temperature and is not restricted by the substrate type and shape. Therefore, it may also expand the possibilities for future applications of coatings for glass windows, optical microscopes, eyeglasses, agricultural greenhouses, and so on.

Recent advances in prevailing antifogging surfaces: structures, materials, durability, and beyond

In past decades, antifogging surfaces have drawn more and more attention owing to their promising and wide applications such as in aerospace, traffic transportation, optical devices, the food industry, and medical and other fields. Therefore, the potential hazards caused by fogging need to be solved urgently. At present, the up-and-coming antifogging surfaces have been developing swiftly, and can effectively achieve antifogging effects primarily by preventing fog formation and rapid defogging. This review analyzes and summarizes current progress in antifogging surfaces. Firstly, some bionic and typical antifogging structures are described in detail. Then, the antifogging materials explored thus far, mainly focusing on substrates and coatings, are extensively introduced. After that, the solutions for improving the durability of antifogging surfaces are explicitly classified in four aspects. Finally, the remaining big challenges and future development trends of the ascendant antifogging surfaces are also presented.