  Liquid marbles refer to liquid droplets that are covered with a layer of
non-wetting particles. They are observed in nature and have practical
significance. However, a generalized framework for analyzing liquid marbles as
they inflate or deflate is unavailable. The present study fills this gap by
developing an analytical framework based on liquid-particle and
particle-particle interactions. We demonstrate that the potential final states
of evaporating liquid marbles are characterized by one of the following: (I)
constant surface area, (II) particle ejection, or (III) multilayering. Based on
these insights, a single-parameter evaporation model for liquid marbles is
developed. Model predictions are in excellent agreement with experimental
evaporation data for water liquid marbles of particle sizes ranging from 7
nanometers to 300 micrometers (over four orders of magnitude) and chemical
compositions ranging from hydrophilic to superhydrophobic. These findings lay
the groundwork for the rational design of liquid marble applications.
