科研之友
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摘要
In the past few years, less attention has been paid tohydrophilicmaterials in frost resistance studies due to the fact that the hydratedlayer may not be able to resist frost formation under cold conditions.Zwitterionic polymers can tightly interact with water molecules throughhydrogen bonding and electrostatic interactions, forming a hydratedlayer that is stable at low temperatures. In this work, polyethyleneimine(PEI) and 1,3-propanesultone (PS) constitute the basis of a zwitterionicpolymer, on which different catechol derivatives such as protocatechualdehyde(PA), protocatechuic acid (PCA), and 4-(chloroacetyl)catechol (CAC)are grafted. These coatings exhibit hydrophilicity with a water contactangle below 10 degrees, where mussel mimetic catechol derivatives areused as anchor points to deposit the coating on the substrate. Inaddition, the relationship between the molecular structure and frostresistance capability was investigated by changing the type of catecholderivative, as well as revealing the frost resistance mechanism ofthe hydrophilic coating. In particular, the PEI-CAC-PS coating hasstrong hydrogen bonding due to the formation of a five-membered ringwith amino and carbonyl groups attached to the same carbon, which,together with the electrostatic interaction, gives the coating a highcontent of nonfreezable water and thus excellent frost resistance.In addition to frost resistance properties, the hydrophilic zwitterionicpolymer coating is multifunctional with antifogging and self-cleaningcapabilities.
