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Exact density functional theory for ideal polymer fluids with nearest neighbor bonding constraints
Clifford E Woodward1, Jan Forsman
1School of Physical Environmental and Mathematical Sciences, University College University of NSW, Australian Defence Force Academy, Canberra, Australian Capital Territory 2600, Australia. c.woodward@adfa.edu.au
The Journal of Chemical Physics
|August 14, 2008
Summary
This study introduces a new density functional theory for ideal polymer fluids using segment end site densities, simplifying free energy calculations. This approach offers improved accuracy compared to previous methods, especially for longer polymers near surfaces.
Area of Science:
- Physical Chemistry
- Polymer Science
- Statistical Mechanics
Background:
- Existing density functional theories for polymer fluids often use complex multipoint distributions.
- Previous work by Tripathi and Chapman (2005) used monomer site densities, showing limitations for longer polymers with attractive surfaces.
Purpose of the Study:
- To develop a new density functional theory for ideal polymer fluids.
- To simplify the mathematical structure of free energy functionals.
- To improve the accuracy of theoretical predictions for polymer behavior.
Main Methods:
- Developed a new free energy functional based on nearest-neighbor bonding constraints.
- Expressed the free energy in terms of end site densities of chain segments.
- Applied the theory to ideal polymer fluids near repulsive and attractive surfaces.
Main Results:
- The new theory provides a simpler mathematical structure for the free energy functional.
- Calculations show improved accuracy compared to theories using monomer site densities, particularly for longer polymers.
- The theory successfully derives an expression for the free energy of infinitely long polymer fluids.
Conclusions:
- Segment end site densities are a more suitable choice for expressing free energy functionals in polymer fluid theories.
- The proposed density functional theory offers a more accurate and mathematically simpler approach to modeling ideal polymer fluids.
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