Liquid chromatography of polymer mixtures by a combination of exclusion and full adsorption mechanisms. Three- and four-component polymer blends

Coupling of full adsorption-desorption and size-exclusion chromatography (F AD-SEC) has been applied to the separation and molecular characterization o f three- and four-component polymer blends. The method is based on the full adsorption of all n or n - 1 components of the polymer blend in a speciall y designed FAD minicolumn. By appropriate eluent switching the adsorbed pol ymers are desorbed stepwise from the FAD minicolumn into an on-line SEC col umn for molecular characterization. It is shown that the desorption isother ms of particular blend components give valuable information about the appro priate displacer composition. The exact position of the desorption isotherm s depends, however, both on the amount of polymer adsorbed and in the prese nce of other, chemically different, polymers within FAD column. The nature and composition of the displacer must, therefore, be adjusted if the interv als between the desorption of particular blend components are to be large e nough to prevent displacement overlap.