Abstract
Osmotic pressure and viscosity measurements afford mutually supplementary data for the thermodynamic parameters governing the interaction between polymer segments and solvent molecules. With the object of studying the effects of the structural characteristics of polymer and solvent on the interaction between polymer segments and solvent molecules, we have performed osmotic pressure and viscosity measurements at different temperatures. It appears that the ϑ temperature deduced from the intrinsic viscosity agrees with that obtained from the second virial coefficient. The entropy of dilution for the polyisobutylene–benzene system appears to be comparable to that found for polydimethylsiloxane in benzene. However, the entropy of dilution has been found to differ widely for a given polymer in different solvents. It appears that the entropy of dilution varies not only with the geometrical character of the solvent molecule in relation to the polymer segment, but also with the preferential ordering induced by the difference in the binding forces between the molecules solvent–solvent, solvent–solute, and solute–solute. A brief discussion is also given on the influence of hindrance to free rotation on the polymer configuration.