A Polymer End-Tethered to a Potential Stripe: A Simple Example of an Escape Transition

We study the problem of a single ideal polymer chain tethered to a surface at the midpoint of a repulsive potential stripe. If the potential is very weak, the chain remains unperturbed. However, as the potential is increased, the chain conformation undergoes a sudden change. The chain forms a tether to the edge of the stripe and moves most of the monomers off to the region of lower potential. This is a simple example of an escape transition previously discussed for compression of polymer chains. We show how these two systems are analogous and clear up some controversy regarding the exact form of the force versus height curve for the compressive system.