2018 Impact factor 1.686
Soft Matter and Biological Physics

Eur. Phys. J. E 3, 343-353

Density functional theory for nonuniform polymer melts: Based on the universality of the free energy density functional

Shiqi Zhou

Research Institute of Modern statistical Mechanics, Zhuzhou Institute of Technology, Wenhua Road, Zhuzhou city, 412008, P. R. China
chixiayzsq@yahoo.com

Received 18 April 2000

Abstract
A density functional theory is proposed for nonuniform freely jointed tangential hard sphere polymer melts in which the bonding interaction is treated on the basis of the properties of the Dirac $\delta$-function, thus avoiding the use of the single chain simulation in the theory. The excess free energy is treated by making use of the universality of the free energy density functional and the Verlet-modified (VM) bridge function. To proceed numerically, one of the input parameters, the second-order direct correlation function of a uniform polymer melt is obtained by solving numerically the Polymer-RISM integral equation with the Percus-Yevick (PY) closure. The predictions of the present theory for the site density distribution, the partition coefficient and the adsorption isotherm, near a hard wall or between two hard walls are compared with computer simulation results and with those of previous theories. Comparison indicates that the present approach is more accurate than the previous integral equation theory and the most accurate Monte Carlo density functional theories. The predicted oscillations of the medium-induced force between two hard walls immersed in polymer melts are consistent with the experimental results available in the literature.

PACS
61.41.+e Polymers, elastomers and plastics

Copyright EDP Sciences, Società Italiana di Fisica, Springer-Verlag