Unbinding transitions of semi-flexible polymers

We consider a semi-flexible chain adsorbed on a wall by a constant external field, h, or a short-range surface potential, V_s. When the amplitude of h or V is decreased the system undergoes an unbinding transition; the properties of such transitions are studied here through various analytical and numerical methods (Flory approximation, scaling arguments, transfer matrix methods and Monte Carlo simulations). In particular, we obtain a general form for the entropy reduction (“steric interactions„) for constrained chains. The unbinding transition from an attractive V_sis shown to be discontinuous in the limit of very rigid chains.