volume change on mixing, and leads to deficiencies similar to in lattice-based
theories. Hence, the effect of pressure on the phase behavior of polymeric sys-
tems cannot be studied.
• The long-range attractive interactions are treated by simple contact forces sim-
ilar to as in lattice-based theories. Hence, the total interaction is proportional
to number of segment-segment contacts, where the proportionality constant is
the Flory-Huggins χ parameter. The definition of χ is generally a convenient
functional fit to describe the experimental phase behavior of the polymeric sys-
tems. These fitting approaches introduces an empirical temperature or even
composition dependence of the χ parameter.
• The mean-field approximations in SCFT neglects the fluctuation effects. This
approximation is incorrect for polymer solutions in the dilute or semi-dilute
regimes, polymer blends near a critical point or second-order phase transi-
tion, microemulsion and micellar phases of surfactants, block copolymers near
order-disorder transition, and polyelectrolyte solutions in various concentration
regimes.
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