Thermodynamics of macromolecular systems

Summary From light scattering measurements in the system polystyrene-cyclohexane-acetone within the temperature range from 288 to 323 K it is concluded that the surface of the reduced chemical potential of the solvent as function of solvent composition and temperature exhibits the characteristics of true cosolvency. The influence of cyclohexane-acetone ratio on the temperature dependence of the corresponding enthalpy and entropy parameters is discussed. The cosolvency effects are evidenced also by studies of the STAUDINGER index at 34.5° C over the whole range of the ternary system.Properties of the binary solvent mixture cyclohexane-acetone, i. e. excess volume and viscosity, indicate that acetone clustering breaks down by dilution with cyclohexane. Consequently, the observed true cosolvency may be interpreted as caused by the combined action of cyclohexane and non-associated acetone.