Thermodynamics of macromolecular systems

Summary

Equilibrium swelling measurements in the system polystyrene — cyclohexane — acetone within the temperature range from 288 to 323 K confirm the conclusion drawn from light scattering investigations (Schuster, R. H., Cantow, H.-J. and Klotz, S., 1982) that the system exhibits the characteristics of cosoivency. A thermodynamic analysis of the experimental data following the Flory-huggins-rehner one-parameter equation in terms of χ, χH and χS is compared with that (Cantow, H.-J. and Schuster, R. H., 1982) based on the free energy two-parameter equation proposed by Koningsveld and Kleintjens. Thus, an unequivocal interpretation of the swelling thermodynamics of the ternary system could be reached, irrespective crosslink density of the network. The cosoivency effects are discussed in relation to the heat of mixing. The conclusion has been proved that the cosoivency is caused by breakdown of acetone clustering by dilution with cyclohexane.