CHROMATOGRAPHIC INVESTIGATIONS OF MACROMOLECULES IN THE CRITICAL RANGE OF LIQUID-CHROMATOGRAPHY .2. 2-DIMENSIONAL SEPARATIONS OF POLY(ETHYLENE OXIDE BLOCK PROPYLENE-OXIDE)

A polyethylene oxide-polypropylene oxide block polymer was characterized with respect to molar mass distribution and block length of the individual blocks using two-dimensional chromatographic techniques. In the first dimension the block polymer was separated according to the length of the polypropylene oxide block by liquid chromatography at the critical point of adsorption. The resulting polypropylene oxide uniform fractions were subjected to supercritical fluid chromatography or size-exclusion chromatography and the average length and the molar mass of the polyethylene oxide blocks were determined for every fraction.