Journal of Chromatography A, 976 (2002) 171–179 www.elsevier.com / locate / chroma Structure characterization of hyperbranched poly(ether amide)s I. Preparative fractionation * Albena Lederer , Dieter Voigt, Carola Clausnitzer, Brigitte Voit ¨ Institut f ur Polymerforschung Dresden e. V ., Hohe Strasse 6, D-01069 Dresden, Germany Abstract 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.  2002 Elsevier Science B.V. All rights reserved. Keywords: Preparative chromatography; Poly(ether amide); Polymers 1. Introduction erties known. Up to now, these systems were either theoretically modeled or correlated to known struc- In contrast to dendrimers, hyperbranched mole- tures. There are numerous examples for detailed cules are not perfectly branched but they resemble theoretical calculations about their molar mass dis- the flow properties of dendrimers due to a similar tribution [4], their dimensions, and their branching dense, branched structure. For this reason, hyper- density profile [5,6]. Other simulations were made on branched molecules are preferably discussed in their intrinsic viscosity behavior in dependence of applications where a reduction in melt or solution the degree of branching [7,8]. Parallels between viscosity is advantageous as in coatings or as pro- hyperbranched and cross-linked systems were drawn cessing additives for linear polymers. They owe their by Burchard [9]. Viscosity and light scattering ex- popularity mainly to the simplicity of their syn- periments, developed for micro gels were also ap- thesis—a one-step polymerization. This, in turn, plied to hyperbranched systems [10–13]. However, results in rather broad molar mass distributions [1– the determination of the gyration and hydro- 3]. For this reason, the determination of the molar dynamical radius remained difficult due to the high mass dependent structure parameters is difficult and, polydispersity of the polymer samples. Indirect proof so far, there was neither a synonymous picture of the of the theoretical studies of the hyperbranched structure of such hyperbranched molecules nor is the systems was obtained by experiments on biopoly- relation of this structure to the macroscopic prop- mers such as amylopectin [14–17], glycogen and dextrin [18–20] or insulin [21], considering them as *Corresponding author. model compounds. 0021-9673 / 02 / $ – see front matter  2002 Elsevier Science B.V. All rights reserved. PII: S0021-9673(02)00937-8