Structure characterization of hyperbranched poly(ether amide)s - I. Preparative fractionation

The focus of our investigation lies on the separation of typically broadly distributed hyperbranched poly(ether amide)s into narrow fractions of various molar masses. Their exact molar mass found via size-exclusion chromatography (SEC) with light scattering detection allows us to use these fractions for sample specific calibration in the SEC investigation of other hyperbranched samples. The analysis of the degree of branching, molar mass and viscosity behavior of the fractions gives a first indication about their molecular shape and the contribution of that shape to the overall viscosity. We determined the Mark-Houwink exponent for a hyperbranched sample using a number of narrow fractions which showed that an increase of molar mass leads to an increased molecular density. (C) 2002 Elsevier Science B.V. All rights reserved.