ABSTRACT
The distribution coefficients of functional macromolecules do depend on the chain length either; they are, however, not equal to unity but are determined by the pore size, the type of the functional groups and their number. Chromatography under critical conditions allows one to subdivide macromolecules according to the types of their molecular and structural heterogeneity. In practice, however, difficulties may be encountered in macromolecular chromatography under critical conditions, associated with either a too large or a too small difference in the adsorption energies of a terminal segment and a chain segment, which leads either to excessively large retention volumes, where peaks are not detected because of the broadening, or to poor resolution. The THF molecules in the previously considered case, interacting vigorously with the OH groups of the polymer, decrease the energy of their interaction with the adsorbent surface, which makes it possible to determine FTD by the SCR method in a heptane-THF binary solvent.
