Electrochemically modulated liquid chromatography of polymers

• Applicant: Dr. Jan-Hendrik Arndt
• Subject Area: Preparatory and Physical Chemistry of Polymers ; Analytical Chemistry
• Term: since 2020
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 446797860

The properties of polymers are, in the case of homopolymers, fundamentally determined by the distribution of the macromolecules with regard to molar mass and microstructure. In the case of copolymers, there is additionally their distribution with regard to chemical composition. Liquid chromatographic methods have been widely established as a means to investigate these distributions. Liquid chromatographic methods may be distinguished with regard to the parameter (molecular weight or chemical composition/microstructure) they discriminate, or by the means by which the separation is achieved. These are in particular gradients with regard to mobile phase composition and temperature. A variety of liquid chromatography, which is completely unknown for polymers so far, is electrochemically modulated liquid chromatography. This method is characterized by the fact that an electric potential is used to influence and control the liquid chromatographic separation, using an electrically conducting stationary phase. The application of this method to the separation of polymers is interesting with regard to several aspects. On the one hand, electrochemically modulated liquid chromatography may achieve higher separation efficiencies than established methods. On the other hand, it holds the potential to allow separations, which are not possible using established liquid chromatographic protocols. For example, the method may allow investigating minute differences in the molecular heterogeneity of the macromolecules (e.g. stereomicrostructure/end-groups) towards which established methods are not sensitive.The project "Electrochemically modulated liquid chromatography of polymers" thus pursues the goal of investigating the possibilities offered by electrochemically modulated liquid chromatography in the area of polymers. The first partial target will be to identify suitable conditions for separating water soluble, synthetic polymers using electrochemically modulated liquid chromatography. In this part of the project, polyethylene oxide, polypropylene oxide and their copolymers, synthesized under variation of their molecular parameters, will be used as model polymers. For these model polymers, an initial set of conditions (solvents) has been identified, which allows their reversible adsorption on the stationary phase. Additional ones will be developed. The second partial target of the project will be to elucidate the separation characteristics of the method further with regard to the model substances. In particular, an understanding of the interrelationship between polymer structure, elution behavior and separation parameters (voltage, temperature, gradient) shall be developed. The third and last partial target of the project will be to extend the application range of the method with regard to a wider range of polymers. The focus will be on the characterization of water insoluble, synthetic polymers for which poly (methyl methacrylate) will be used as a model.

• DFG Programme: Research Grants