Propagation of wetting lines for various interfaces formed between oil, water, and air on a highly viscoelastic, polymeric surface were investigated. The wetting of the acrylic polymer shows complex as well as diverse patterns. Stick and break motions of the three-phase line, characteristic of its halting due to ridge formation, appeared in either advancing or receding motions, in both directions or not at all. Such experiments demonstrate the various wetting behaviors possible on a soft, viscoelastic surface. A comprehensive explanation based on the vertical capillary force component is provided, which is consistent with these as well as previous observations.
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This work is financially supported by the U. S. Department of Energy, Project No. DE-FC36-04GO14309.