Re­search

Our research activities shall unravel mechanisms of intramolecular and supramolecular structure formation in nature and in synthetic systems. Final objective is the development of tools to control these processes. Time-resolved static light scattering (TR-SLS) and dynamic light scattering (TR-DLS), small angle neutron scattering (SANS) and small angle X-ray scattering (SAXS) are predominantly used to gain insight into the mechanisms of these structural transformations. Five related topics can be distinguished.
Macromolecular Crowding

Conformational changes of proteins or DNA as well as the formation of hierarchical structures with proteins are common processes in living cells. Their investigation in vitro is usually based on experimental conditions with properly adjusted pH, salinity, temperature and concentrations of the components directly involved in the respective process. Although such in vitro experiments provide first insights into the mechanisms of the processes under consideration, they totaly neglect the crowded environment in cells, generated by the presence of osmolytes, chaperones and the many other…
Self-Assembly of Dyestuffs and Proteins

Numerous synthetic, low molecular weight compounds like organic azo-dyestuffes form fiber-like aggregates in aqueous solution in close analogy to the self-assembly of various proteins in living systems. The underlying processes can be regarded as physical polymerisations leading to a structural diversity, just as complex as in case of macromolecular chemistry. Several low molecular weight gelators and dyestuffs, with the cationic dyestuff pseudo-isocynanine chloride (PIC) as the most recent example, have been selected for a detailed investigation of their self-assembly with time-resolved light…
Nucleation and Growth of Nano-Particles

Nucleation and growth of particles are essential features of the formation of stable and metastable solid phases in a bottom-up approach and are thus of fundamental relevance to countless processes in nature and industry. Typical examples are the formation of nanoparticles from supersaturated solutions of carbonates, phosphates and silicates relevant to biomineralization and scale formation in pipes, the generation of high performance nanoparticles of noble metals or of metal organic frameworks (MOF) and, to give but an example from organic chemistry, the growth of eumelanin based biological…
Polyelectrolytes

Anionic polyelectrolyte chains act extremely sensitive towards the addition of specifically interacting cations (SIC). This sensitive response can be further modulated by variations of pH, temperature and ionic strength with additional inert salts. Typical SICs, which interact specifically with the anionic carboxylate residues of polyacrylates or with the anionic sulfonate residues of poly(styrene sulfonate) are alkaline earth cations. This is signaled by a drastic change of the polyelectrolyte coil dimensions and eventually in a precipitation of the respective polyelectrolyte salt, once the…
Polylactides as Biobased Materials

Materials from biobased polymers are considered by the EU to be of high priority. Accordingly, the research project PLANOM aims at a use of polylactides for optical applications like lenses, reflectors or light guides, where it is supposed to replace poly(methyl methacrylate) and polycarbonate. Our group contributes to this project with two topics: (i) Polymers, predominantly polylactides and colloidal or polymeric additives will be characterized by means of light scattering or Fraunhofer diffraction. These characterization techniques reveal the molar mass and or the size of the respective…