An Ice Structuring Mechanism for Zirconium Acetate

The control of ice nucleation and growth is critical in many natural and engineering situations. Yet, very few compounds are able to interact directly with the surface of ice crystals. Ice-structuring proteins, found in certain fishes, plants and insects, bind to the surface of ice, thereby controlling their growth. We recently revealed the ice-structuring properties of zirconium acetate which are similar to those of ice-structuring proteins. Being a salt, and therefore different from the proteins having ice-structuring properties, its ice-structuring mechanism remains unelucidated. Here we investigate this ice-structuring mechanism through the role of the concentration of zirconium acetate and of the ice crystal growth velocity. We then explore other compounds presenting similar functional groups (acetate, hydroxyl, or carboxylic groups). Based on these results, we propose that zirconium acetate adopts a hydroxy-bridged polymer structure which can bind to the surface of the ice crystals through hydrogen bonding, thereby slowing down ice crystal growth.