(Phys.org) —When a rubber ball and a droplet of water are compressed onto a solid surface, they behave very differently. For the ball, the compression process is reversible, so the ball retains its original form when decompressed. In contrast, the compression process for the water droplet is irreversible, and the droplet's contact angle with the surface irreversibly changes because of the way the droplet interacts with the surface's chemical or physical inhomogeneities.
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