H.-M. Petri and B. A. Wolf
"Composition Dependent Flory-Huggins-Parameters: Molecular Weight Influences at High Concentrations"
Macromolecular Chemistry and Physics 1995, 196, 2321-2333.
Abstract: Flory-Huggins interaction parameters chi were determined by means of equilibrium vapor pressures (measured via a combination of a head space sampler with a gas chromatograph) and light scattering as a function of composition and temperature for the systems cyclohexanone/polystyrene [CHO/PS] and cyclohexanone/poly(butyl methacrylate) [CHO/PBMA]. The investigation of molecular weight influences on chi with the system CHO/PBMA demonstrates that they persist almost up to the pure polymer. In order to rationalize this result, it is postulated (in accord with experimental findings and theoretical predictions) that the dimensions of polymer chains may vary upon the addition of solvent even in highly concentrated solutions. From the information concerning chi (T) the interaction parameters were split into their enthalpy and entropy part. In the case of CHO/PS these quantities vary considerably with composition and turn out to be linearly interrelated.
preprint number: 159