GENERALIZED FLORY EQUATIONS OF STATE FOR HARD HETERONUCLEAR CHAIN MOLECULES

The generalized Flory (GF) and generalized Flory-dimer (GFD) equations of state have been extended to fluids containing hard heteronuclear c hain-like molecules. Compressibility factor expressions have been deri ved for block, alternating and random ''copolymer'' fluids. The effect of composition and the relative size of the segments of a heteronucle ar chain on the compressibility factor are studied. We have also perfo rmed molecular dynamics computer simulations on these systems using an extension of Rapaport's algorithm in which the chains are effectively treated as hard spheres of different sizes held together by invisible strings. The compressibility factors predicted by the GFD theory for heteronuclear chain fluids are in very good agreement with our compute r simulation results. The predictions of Chiew's Percus Yevick theory are also in very good agreement with our computer simulation results o n block copolymers. (C) 1996 American Institute of Physics.