Development of two-dimensional chromatographic methods for the separation and characterization of polyesters of different degrees of branching

The demand for new and innovative products with new or improved properties leads to the synthesis of a large variety of new complex polymer structures. One way to synthesize structures with new or improved properties is the introduction of branches. The introduction of branches results however in an another type of heterogeneity besides the most commonly known according to molar mass, making the characterization of these complex structures more complicated. However, there is a need for the characterization of these complex structures, since the knowledge of the detailed topological characteristics and their effect on material properties will ultimately allow the design of new tailor made high-performance polymers. Thus, the necessity for new characterization methods grows. These methods should allow understanding the molecular structures of such polymer products in order to relate them to the observed macroscopic properties. The aim of the present thesis was to develop new liquid chromatographic methods for the characterization of the degree of branching (DB) and DB distribution of branched polyesters in order to gain a better understanding on how branching influences the structure-property relationship of polymeric materials. Present analytical techniques for the characterization of linear and branched polyesters do not exist or are limited to yield only average values on e.g. the DB of the whole sample. However, for a detailed characterization of branched polymers, more information than the average DB has to be obtained. Therefore, the focus on the method development within this PhD thesis was on conventional and multidimensional liquid chromatographic techniques, which allow a more detailed characterization of linear and branched polymers