SIZE-SENSITIVE FRACTIONATION BY HIGH OSMOTIC-PRESSURE CHROMATOGRAPHY USING CONTROLLED-PORE GLASSES

High osmotic pressure chromatography (HOPC), recently developed to sep arate a large amount of polydisperse polymer with respect to molecular weight, was carried out by using controlled-pore glasses (CPG) as sep arating media. HOPC is based on the partitioning of a polymer solution with a porous medium specific to high concentrations that exert a hig h osmotic pressure. The molecular weight distributions of the initial fractions separated were much narrower compared with those obtained by using silica gels, as CPG has a narrower distribution in the pore siz e. Furthermore, CPG with a larger pore size produced initial fractions with a higher molecular weight, thereby demonstrating that HOPC works on the basis of size exclusion even at high concentrations. The separ ation was optimal when the ratio of the radius of gyration of the inje cted polymer to the pore radius was between 1 and 2. The ratio is seve ral times as large as the one commonly used in gel permeation chromato graphy (C) 1997 Elsevier Science Ltd.