The Inhibition of Icing and Frosting on Glass Surfaces by the Coating of Polyethylene Glycol and Polypeptide Mimicking Antifreeze Protein

The development of anti-icing, anti-frosting transparent plates is important for many reasons, such as poor visibility through the ice-covered windshields of vehicles. We have fabricated new glass surfaces coated with polypeptides which mimic a part of winter flounder antifreeze protein. We adopted glutaraldehyde and polyethylene glycol as linkers between these polypeptides and silane coupling agents applied to the glass surfaces. We have measured the contact angle, the temperature of water droplets on the cooling surfaces, and the frost weight. In addition, we have conducted surface roughness observation and surface elemental analysis. It was found that peaks in the height profile, obtained with the atomic force microscope for the polypeptide-coated surface with polyethylene glycol, were much higher than those for the surface without the polypeptide. This shows the adhesion of many polypeptide aggregates to the polyethylene glycol locally. The average supercooling temperature of the droplet for the polypeptide-coated surface with the polyethylene glycol was lower than for the polypeptide-coated surface with glutaraldehyde and the polyethylene-glycol-coated surface without the polypeptide. In addition, the average weight of frost cover on the specimen was lowest for the polypeptide-coated surface with the polyethylene glycol. These results argue for the effects of combined polyethylene glycol and polypeptide aggregates on the locations of ice nuclei and condensation droplets. Thus, this polypeptide-coating with the polyethylene glycol is a potential contender to improve the anti-icing and anti-frosting of glasses.