Escape Transition of a Grafted Polymer Chain

The escape transition of a flexible polymer chain of chain length N, end-grafted at a hard wall and compressed by a piston of radius R in good solvent conditions, is studied by Monte Carlo simulation and by phenomenological arguments. In contrast to previous theories which have predicted a jump in the force f at a critical value H t of the height H of the piston above the wall, we find that the transition (which is sharp only for N → ∞) is characterized by a flat region of f in the f — H isotherm, i. e. a jump in the height occurs at the transition from H esc , t to H imptt , with (H imp , t — H esc , t )/H esc , t ≈ 0.26. At the transition the constant force f t is predicted and observed t…