ABSTRACT
Thermodynamics is a subject that describes the essential relationships between macroscopic properties. The thermodynamic properties of polymer solutions are independent of chain flexibility. The exceptions to this rule are in those systems where the polymers are stiff rods and those where there are strong specific interactions such as hydrogen bonds. There are essentially two ways of determining solubility parameters for polymers. One is experimental and usually involves the swelling of a lightly cross-linked polymer in a series of solvents. Accordingly, the second method for determining solubility parameters is the most common and this involves a calculation based on so-called group contributions. An expression for the free energy of the system defined by the sphere “occupied” by a polymer chain can be written as the sum of contributions from the mixing of segments with solvent molecules and from elastic deformation of the chains.
