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Title: Self-spreading of the wetting ridge during stick-slip on a viscoelastic surface

Dynamic wetting behaviors on soft solids are important to interpret complex biological processes from cell–substrate interactions. Despite intensive research studies over the past half-century, the underlying mechanisms of spreading behaviors are not clearly understood. The most interesting feature of wetting on soft matter is the formation of a “wetting ridge”, a surface deformation by a competition between elasticity and capillarity. Dynamics of the wetting ridge formed at the three-phase contact line underlies the dynamic wetting behaviors, but remains largely unexplored mostly due to limitations in indirect observation. Here, we directly visualize wetting ridge dynamics during continuous- and stick-slip motions on a viscoelastic surface using X-ray microscopy. Strikingly, we discover that the ridge spreads spontaneously during stick and triggers contact line depinning (stick-to-slip transition) by changing the ridge geometry which weakens the contact line pinning. Finally, we clarify ‘viscoelastic-braking’, ‘stick-slipping’, and ‘stick-breaking’ spreading behaviors through the ridge dynamics. In stick-breaking, no ridge-spreading occurs and contact line pinning (hysteresis) is enhanced by cusp-bending while preserving a microscopic equilibrium at the ridge tip. We have furthered the understanding of spreading behaviors on soft solids and demonstrated the value of X-ray microscopy in elucidating various dynamic wetting behaviors on soft solids as well asmore » puzzling biological issues.« less
Authors:
ORCiD logo [1] ; ORCiD logo [2] ;  [3] ; ORCiD logo [4]
  1. Pohang University of Science and Technology (South Korea). X-ray Imaging Center, Department of Materials Science and Engineering; Korea Atomic Energy Research Institute (South Korea). Neutron Science Division, Research Reactor Utilization Department, Korea Atomic Energy Research Institute
  2. Clemson Univ., SC (United States). Department of Mechanical Engineering
  3. Argonne National Lab. (ANL), Argonne, IL (United States). Advanced Photon Source (APS). X-ray Science Division
  4. Pohang University of Science and Technology (South Korea). X-ray Imaging Center, Department of Materials Science and Engineering
Publication Date:
Grant/Contract Number:
AC02-06CH11357
Type:
Accepted Manuscript
Journal Name:
Soft Matter
Additional Journal Information:
Journal Volume: 13; Journal Issue: 44; Journal ID: ISSN 1744-683X
Publisher:
Royal Society of Chemistry
Research Org:
Argonne National Lab. (ANL), Argonne, IL (United States)
Sponsoring Org:
USDOE Office of Science (SC), Basic Energy Sciences (BES) (SC-22); Korea Institute for Advancement of Technology (KIAT)
Country of Publication:
United States
Language:
English
Subject:
59 BASIC BIOLOGICAL SCIENCES; 47 OTHER INSTRUMENTATION
OSTI Identifier:
1422550