This U.S.-Czechoslovakia research project in chemistry is between Dr. David Hunkeler of Vanderbilt University and Dr. Dusan Berek of the Polymer Institute, Slovak Academy of Science. The researchers will use the concept of chromotographic invisibility to identify critical conditions where the retention volume of a polymer in a mixed element is independent of molecular weight. They will compare two approaches for generating critical conditions: (1) Belenki's method where the elution strength of the binary mixture is varied to control the adsorption and exclusion of the macromolecules and (2) the Hunkeler-Macko-Berek technique where the thermodynamic quality of the mobile phase is varied to balance the free energy of adsorption and precipitation with that of redissolution and exclusion. The influence of temperature, pressure and sample concentration on the behavior of selected polymers at their critical conditions will also be evaluated. The critical conditions will be correlated with properties which characterize the macromolecule in solution. The identified critical conditions will then be applied to the separation and identification of polymer blends and block and graft copolymers according to their molecular weight and composition. This project in polymer research fulfills the program objective of advancing scientific knowledge by enabling leading experts in the United States and Eastern Europe to combine complementary talents and pool resources in areas of strong mutual interest and competence.
