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
-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
