Sk. Nath et al., DENSITY-FUNCTIONAL THEORY OF POLYMER-POLYMER PHASE-SEPARATION BEHAVIOR, Journal of polymer science. Part B, Polymer physics, 33(17), 1995, pp. 2307-2317
Polyatomic density functional theory is applied to a binary polymer bl
end. The polymer reference interaction site model (PRISM) liquid state
theory provides the homogeneous state correlation functions necessary
for the application of density functional theory. An effective chi pa
rameter can be recognized from the density functional expression; howe
ver, the phase separation criteria does not depend solely upon the chi
parameter, rather it depends upon various combinations of the species
-dependent direct correlation functions of the blend. The Flory-Huggin
s chi parameter along with the associated phase diagram is obtained wh
en the monomer volumes of the blend species are equal and for a range
of monomer-monomer attractive interactions. Calculations are performed
both with and without the assumption of incompressibility. The densit
y functional theory along with the PRISM determined ''input'' predict
that an isotopic polymer blend shows an upper critical solution temper
ature (UCST) phenomena. (C) 1995 John Wiley & Sons, Inc.