Design,fabrication And Performance Of The Bionic Antifogging And Frost-resistant Coating

The phenomenon of fog and frost universally existed in nature seriously hinders the light transmission of transparent materials,which brings lots of inconvenience and even poses a serious threat to human safety.For example,the fog on abdominal gastroendoscope,laryngeal lens or eye mask of medical protective clothing will affect the normal use of those instruments;Severe fogging on the surface of solar panels,agricultural greenhouse film significantly reduce the visible light transmission,weaken the efficiency of light energy conversion,finally causing the huge economic losses.In addition,fogging on windshield and rearview mirrors of airplanes and cars might cause serious traffic accidents,owing to the blurred vision.To sum up,there is an urgent need for anti-fog and anti-frost surfaces in production and daily life.In recent years,great progress has been made in the research of anti-fogging surfaces,and the trend of multi-disciplinary research and multi-function combination has emerged.However,how to improve the scratch resistance and durability of the coating basing on the excellent anti-fog and anti-frost property is still a great challenge in the practical application.For the weakness of biocompatibility,complicated preparation process,low hardness and low adhesion of the traditional hydrophilic coatings,this work reported a series of anti-fog and anti-frost coatings were prepared which inspired by the phenomenon that the plant roots in cold zone could not be freezed.By investigating the frost-resistance mechanism of cold zone plant root-stem,differential scanning calorimetry(DSC)and thermogravimetric(TG)tests,the frost-resistance mechanism of the root-stem were analyzed.Based on this bionic prototype,the hydroscopic gel coating was prepared,which is suitable for various transparent substrates.In this study,aiming at the physical and chemical properties of antifogging and frost-resistant surface,the construction strategies and preparation methods of traditional antifogging and frost-resistant surface were studied.Different from the traditional superhydrophilic and superhydrophobic surface,a new strategy of bionic coating was proposed based on the moderate water absorption performance.In this paper,various antifogging and frost-resistant coatings were prepared according to the methods of thermal initiation,photoinitiation and hydrothermal dissolution Their antifogging and frost-resistant properties,transmittance,self-repair properties,adhesion properties,scratch resistance performance were tested.This article mainly introduces three recently research works:Firstly,a hydroscopic coating with block copolymerization of hydrophilic and hydrophobic monomers was prepared by balancing the hydrophilic and hydrophobic surface of the coating.Then,the water absorption rate of the coating was controlled by adjusting the cross-linking density of the coating.In order to improve the biocompatibility and durability of the coating,the polyvinyl alcohol(PVA)hydrogel coating was prepared.The coating possesses great antifogging,frost-resistance and hydrogen bond self-repair properties.The coating was prepared by dissolving polyvinyl alcohol in ultrapure water and using salicylic acid(SA)to increase the mechanical stability and durability of the coating by constituting network crosslinking.Owing to its good biocompatibility,coating can be applied to the surface of medical larynx and gastrointestinal endoscope to prevent fog formation.To further improve the self-healing properties of the antifogging and frostresistance coating,the addition of host-guest crosslinking agent CD-AAM/Ad-AAM endows the coating with self-healing property.Different from PVA hydrogen bond self-healing,host-guest coatings possess excellent self-healing ability,the coatings can realize self-healing during the process of atomization and antifogging.The block gel can also recover its original mechanical properties in wet environment.