  We investigate the binding transition of two flexible polymers grafted to a
steric surface with closeby end points. While free polymers show a
discontinuous transition, grafting to a steric flat surface leads to a
continuous binding transition. This is supported by results from Metropolis and
parallel multicanonical simulations. A combination of canonical and
microcanonical analyses reveals that the change in transition order can be
understood in terms of the reduced translational entropy of the unbound
high-temperature phase upon grafting.
