Phase transition of lattice polymer systems

Abstract

Monte Carlo simulations of a lattice polymer system of chains of N=20 segments each, comprising a total of 21 chains on a 21×21 square lattice, are carried out in order to clarify recent controversies concerning statistical thermodynamics of lattice models of polymers. Assuming an energy ε≳0 for every right-angle step, we find a first-order phase transition of disordered phase to an ordered state at kBTc/ε≊0.93, as demonstrated by discontinuities in the internal energy (conformational order) and the orientational order parameter. Comparison of our results with the predictions of the mean-field lattice theory of Flory and the implications of these findings on phase transitions of real polymer systems are discussed.