Research

Short description of scientifc interests

  We have experience in the preparation of complex polymer architectures and their nanostructured aggregates for soft matter applications. For this reason, we use modern methods of polymer synthesis (controlled radical and anionic polymerization; see e.g. Polym. Chem. 2013, 4, 3885) and subsequent hybrid formation with inorganic components (Chem. Mater. 2015, 27, 7306; PCCP 2015, 17, 11490; Macromol. Rapid Commun. 2016, 37, 1446). This leads to stimulisensitive, colloidal and surface-bound systems.

     While we use for colloidal systems mainly (time-resolved) scattering methods (e.g. combined static and dynamic light scattering: ACS Macro Lett. 2012, 1, 504; small angle x-ray scattering SAXS: Soft Matter 2016, 12, 5127; ACS Macro Lett. 2017, 6, 711; stopped flow: J. Phys. Chem. B 2017, 121, 6739) and analytic ultracentrifugation AUC (Polymer 2013, 54, 6877; ACS Macro Lett. 2017, 6, 711), we employ experiments at the Langmuir trough (Soft Matter 2015, 11, 3559; selected as Soft Matter HOT Paper) and electrochemistry for the investigation of interfacial phenomena.

    Impedance spectroscopy helped to identify the inner structure of adsorbed polymer and enzyme layers for biosensor applications (Langmuir 2015, 31, 13029; Biomacromolecules 2014, 15, 3735). For these biosensing applications, the beneficial properties of microgels are employed (Acc. Chem. Res. 2017, 50, 131). Further, a combination of hydrodynamic voltammetry / impedance spectroscopy clarified the electron transfer paths in complex colloidal mixtures, like porous microgels in presence of absorbable electroactive units (J. Phys. Chem. C 2014118, 26199).

---  Furthermore, electrochemistry could be introduced as novel stimulus for the manipulation of microgel and interfacial properties (Chem. Mater. 2015, 27, 7306; Chem. Sci. 2019, 10, 1844; Langmuir 2021, 37, 1073). Finally, the influence of architecture on the adsorption properties of polyelectrolytes was investigated by hydrodynamic voltammetry (Electrochim. Acta 2017, 232, 98; Polymers 2018, 10, 429)..

  In all of these examples, polymer complexation plays a crucial role. Architectural effects on the polymer complexation and the structure of the resulting micelles have been demonstrated (thermodynamic analysis of  complexation: ACS Macro Lett. 2012, 1, 504; PCCP 2014, 16, 4917; Soft Matter 2015, 11, 3559; Langmuir 2017, 33, 4091: cover image).  ... 

 The comparison of complexing abilities of polymers in dispersion and at interfaces showed that an enhanced interaction at liquid-liquid interfaces can be detected.

   A relatively new and important research area deals with (micellar) nonequilibrium structures. In future, these could allow a triggered release, adhesion or in vivo gelation. We could demonstrate (Adv. Mater 2017, 1703495) that kinetically-trapped micellar structures transform into other morphologies after triggering on demand. Both a short temperature cycle or a pressure application enable the gelation of a micellar dispersion at otherwise constant conditions. 

+++Based on the work related to interpolyelectrolyte complexes (ACS Macro Lett. 20176, 711; J. Phys. Chem. 2017121, 6739; Soft Matter 201612, 5127) we could adapt a system, where nonequilibrium micelles can be restored easily after triggering (ACS Macro Letters 20187, 341). AUC (ACS Macro Lett. 20176, 711) and especially SANS and SAXS is employed for structural analysis. 

  In all these areas, we strive for a deep understanding by comparing experiment with theory and simulation (ACS Macro Lett. 2012, 1, 504; Macromol. Rapid Commun. 2013, 34, 855; Macromol. Theory Simul. 2015, 24, 110; Soft Matter 2015, 11, 3559; Macromolecules 2016, 49, 8748).