Entwicklung von kombinierten Methoden

Combined characterisation, e.g. hyphenated and correlated methods often allows information not available via separated methods. One Example is shear induced crystallisation in Rheo-NMR, anotherone SEC combined with IR. This already represent the two main fields of this research strand: Combination with rheology and new detectors for chromatograpy, eg. size exclusion chromatography (SEC).

Rheology addresses macroscopic mechanical properties of polymers. However, additional information on the molecular scale is often necessary for a full interpretation of rheological results. Therefore, the simultaneous use of rheology with other methods is highly beneficial. So far, we have coupled small-angle X-ray scattering (SAXS), dielectric spectroscopy and low-field 1H-NMR relaxation spectroscopy with rheology [Ratzsch et al., 2017]. As an actual project, we work on the combination of rheology and IR spectroscopy.

This offers the possibility to identify and quantify also rare groups, e.g. end groups or branching points. Only the combination of these three methods in one combined technique offers the possibility of correlated information, e.g. the change in composition or branching degree as a function of molecular weight. FT-IR-SEC is developed to a final state, the combinations with an IR-Laser (QCL) is already working [Morlock et al., 2018]. Actual, we can detect one Carbonyl-Group in a polymer of 500.000 g/mol, but further improvements in sensitivity and especially for accessible functional groups are still necessary.