POLYMER-SOLVENT INTERACTION PARAMETER CHI

The polymer-solvent interaction parameter CHI introduced by M. L. Huggins and P. J. Flory has been widely used during the last third of a century to characterize solutions comprising a high-molecular-weight polymeric component and a low-molecular-weight solvent. In the sections to follow, the interaction parameter is assigned a definition which is more general than originally intended by Huggins and Flory but which is more suitable for current use. Expressions relating CHI to several observable thermodynamic properties are presented, and measured values of CHI are tabulated as a function of both temperature and concentration for a number of binary polymer-solvent systems. This review also contains a brief summary of several theories of polymer solutions which yield expressions for predicting values of CHI . It is demonstrated that the values of CHI obtained either from experiment or theory can be utilized for predicting the colligative properties and determining the solubility characteristics of polymer-solvent systems. Extensive experimental data are tabulated.