The name is absent

monomer or statistical segment length-level information rather the coarse-grained
representation of the polymers. Thus, DFT provides an approach that is intermediate
between macroscopic thermodynamic approaches and truly microscopic simulation-
based methods. The theory incorporates molecular-level detail but is simple enough
that calculation time is modest and physical insight is retained even in complex sit-
uations. Again, all the mean field theories and SCFTs neglect compressibility and
the fluctuations in the local composition from an average value. However, as with
bulk polymer systems, compressibility effects play an important role in inhomoge-
neous systems. The natural formalism of the DFTs is the grand canonical ensemble
where fluctuations in the number of polymer chains in the system keep the chemical
potential constant. Thus the system is compressible and phase transitions can include
fluctuations in density∕composition of the system. In addition, DFTs provide a single
framework for modeling both interfacial and bulk properties. A thorough review of
classical DFT is given by Evans [56] while many applications of DFT to interfacial
systems are described by Davis [57] and Wu [55].

Owing to its success for homogeneous systems, several DFTs based on TPTl
have been proposed. As noted by Chapman [58] and Kierlik and Rosinberg [59],
Wertheim’s theory is written in general for inhomogeneous associating (atomic) flu-
ids. The central approximation of any density functional theory is an expression for
the intrinsic Helmholtz free energy of the system. Considering the polyatomic system
as a mixture of associating spherical segments in the limit of complete association,

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