Theory of the molecular origins of the entropic portion of the Flory χ parameter for polymer blends

Abstract
The lattice model of self- and mutually avoiding polymers is used to compute corrections to the Flory–Huggins entropy of mixing for binary blends of polymers in which the monomers have specific geometric structures and therefore occupy several lattice sites. Ten examples provide an entropic χ of close to the magnitude observed experimentally, thereby giving the first molecular basis for understanding the previously enigmatic and ad hoc entropic χ parameter.