Integral equation theory of homopolymer melts
A general theory is developed for the equilibrium structure of dense polymer melts. This theory is based on an integral equation approach developed by Chandler and coworkers for molecular liquids. We are able to construct a tractable formalism for the polymer problem by employing the fact that a polymer molecule in a melt is ideal. This leads to a set of integral equations for the intermolecular radial distribution functions. In the case of a long linear chain this set approximately reduces to a single integral equation which we have solved numerically for the case of Gaussian and freely-jointed chain intramolecular statistics with repeat units interacting via hard core repulsions. From this solution we obtained the radial distribution function, structure factor, and compressibility as functions of liquid density and degree of polymerization. Unlike the random phase approximation (RPA) approach of deGennes, the present theory allows for density fluctuations. These density fluctuations, which decay on a length scale comparable to a few monomer units, are crucial for the calculation of the structure factor and thermodynamic properties such as the equation-of-state of the polymer fluid. Generalizations of the present theory to include chain stiffness effects and attractive interactions are possible.
- Research Organization:
- Sandia National Labs., Albuquerque, NM (USA)
- DOE Contract Number:
- AC04-76DP00789
- OSTI ID:
- 5682689
- Report Number(s):
- SAND-87-2333C; CONF-871190-3; ON: DE88005304
- Country of Publication:
- United States
- Language:
- English
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