Effect of chain stiffness on the conformational properties, pair correlations, and equation of state of polymer melts

The effect of molecular stiffness on the local structure and thermodynamic properties of semiflexible polymer melts is investigated via Monte Carlo simulation. Contrary to what might be expected from simple packing arguments, increasing the stiffness tends to decrease the tendency for segments on different chains to layer against each other, although the value of the pair correlation function at contact does increase. The pressure is relatively insensitive to the stiffness of the molecules because an increase in the two-body contribution to the pressure is compensated for by a decrease in the three-body contribution. Comparison of self-consistent polymer reference interaction site model predictions to the simulations shows that the accuracy of the theory for the pair correlation function diminishes somewhat as the chains become stiffer.