Dry water: From physico-chemical aspects to process-related parameters

Water-rich powders known as “dry water” consist of aqueous liquid droplets encapsulated by a protective shell formed by self-assembled superhydrophobic nanoparticles. The water-rich product contains considerable amounts of aqueous liquids (up to 98% w/w). However, despite this large amount of liquid, the product possesses the same flow properties as a dry powder. Water can easily be released by mechanical stress, e.g. by rubbing it onto the skin. The process does not make use of any organic solvent and can easily be developed on an industrial scale. Although “dry water” has been known since the 1960s, it is only recently that fundamental aspects of water encapsulation in dry water have been studied. This paper aimed to describe the elementary mechanisms responsible for dry-water formation. It was found that the success of encapsulation depends on the relative importance of process-related parameters with respect to the physico-chemical properties of the material used. A “regime map” for dry water production is also proposed based on comparison between the mechanical energy due to stirring and the energy of immersion of particles.