| The world of materials physics is full of finite size effects. Boundaries are as important to liquid crystalline materials as to polymeric materials. In this finite world, we can hardly avoid interfaces. Polymer-liquid/solid interfaces are rather unique from a mechanical viewpoint. Our assumption of the no-slip boundary condition since mid 1800s ends with polymers. Polymers of high molecular weight give Navier an impressive example of slip boundary condition, as first recognized by de Gennes. More importantly, wall slip is a primary indication that the conventional continuum mechanical description of viscoelastic materials may break down. In this talk, we review some of the latest breakthroughs in our field of rheology. The results show that large deformation behavior of entangled polymeric liquids needs to be depicted in terms of the notion used to describe the physics behind wall slip.
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