The nature of the globule-coil transition of surface-confined polymers has been an issue of debate. Here this 2D collapse transition is studied through a partially directed lattice model. In the general case of polymers with positive bending stiffness ($\Delta >0$), the collapse transition is first order; it becomes second order only in the limiting case of zero bending stiffness ($\Delta \equiv 0$). These analytical results are confirmed by Monte Carlo simulations. We also suggest some possible future experiments.

• Received 7 April 2006

DOI:https://doi.org/10.1103/PhysRevLett.97.158302