GENERALIZED FLORY EQUATION OF STATE FOR HARD CHAIN HARD MONOMER MIXTURES OF UNEQUAL SEGMENT DIAMETER

A generalized Flory equation of state is derived for hard chain-hard m onomer mixtures, where the monomer diameter is different from the chai n segment diameters. An alternate derivation of the osmotic equation o f state for binary mixtures is also presented; the equation is derived by inserting both species simultaneously into the fluid. The alternat e osmotic equation of state, combined with the generalized Flory theor y, predicts the conformal solution mixing rule when the monomer and ch ain segments are of the same diameter. Chain insertion probabilities, required in the osmotic equation of state in order to predict thermody namic properties, are estimated using monomer mixture insertion probab ilities based on the equation of state of Mansoori et al. and the gene ralized Flory theory. An extensive set of hard 4-mer-monomer and hard 8-mer-monomer Monte Carlo simulations have also been performed. Simula tion compressibility factors are compared to the new equation of state 's predictions; agreement is quite good.