| Abstract
| - The influence of hyperbranched polyesters with different functional end groups on the surface tensionof mixtures with an oligo(ester diol) was investigated. The temperature dependence of the surface tensionof the pure components and of the mixtures was measured by a modified Wilhelmy balance technique. Theresults indicate that the surface tension of the pure hyperbranched polyesters strongly depends on thefunctionality of the end groups. The functionalization of the hydroxyl end groups by short alkyl chains(methyl, tert-butyl) reduced the surface tension depending on the degree of substitution. The surfacetension of the mixtures with the hydroxyl-terminated hyperbranched polyester was slightly increased athigher concentrations of the hyperbranched polymer compared to the surface tension of the pure ester diol.On the other hand, the surface tension of mixtures could be considerably decreased using 1% of hyperbranchedpolyester polyols partially substituted with short alkyl chains. In that case, the modified hyperbranchedpolyesters act as surface active agents. On the molecular level, the enrichment of the modified hyperbranchedpolyester in the surface region was proven by X-ray photoelectron spectroscopy measurements.
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